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5632 articles

B1792 – Vapour pressures and excess functions of (3,5 ; 2,6)dimethylpyridine + n-hexane, n-heptane and n-octane measurement and prediction-ru

The vapour pressures of liquid (3,5; 2,6)-dimethylpyridine + n-hexane; +n-heptane and +n-octane mixtures were measured by a statistic method, respectively, between 263.15-353.15K at 10K intervals. The pure component vapour pressures data and those of mixtures were correlated with the Antoine equation. The excess enthalpies, at 303.15K for those mixtures were measured by an isothermal calorimeter model C80 SETARAM. The molar excess Gibbs energies, calculated from the vapour liquid equilibrium data and the molar excess enthalpies compared satisfactorily with group contribution method (DISQUAC).

A1130 – Synthesis and crystal structure of three-dimensional open-framework lanthanide oxalates containing either the guanidinium or tetramethylammonium ions-fr

Single crystals of three new lanthanide oxalate complexes, (CN3H6)2[Nd(H2O)]2(C2O4)4.3H2O I, [N(CH3)4][Nd2(H2O)3](C2O4)3.5. 4H2O II and [N(CH3)4][Yb(C2O4)2] III, have been synthesized hydrothermally in presence of either the guanidinium or tetramethylammonium TMA ions. A relevant feature of III is the complete absence of water. For all the complexes, the three-dimensional framework structure is built up by the connections of the lanthanide and the oxalate units, forming cavities and channels where the guest species, guanidinium and TMA ions and free water molecules, are localized. Thus, the above complexes present a very open architecture. For I and II, the neodymium atoms are 9-coordinated, forming a distorted monocapped square antiprism while for III, the ytterbium atom is 8-coordinated forming a quite regular dodecahedron. For I, the dehydration process is partially reversible. All the complexes will be characterized by infrared spectroscopy and thermal analysis. I has been extended to other lanthanide forming a family, Ln = La-Eu.

A0201 – Regulating step in LaNi 5 hybride formation kinetics

N. Gerard et al, Int Symp Reactivity Solids DIJON (1984)

A0200 – Thermal decomposition of aluminium, iron and manganese complexes of urea

G.E. Peters, Thermochimical Action 73 (1984) 79

A0200 – Thermal decomposition of aluminium, iron and manganese complexes of urea

G.E. Peters, Thermochimical Action 73 (1984) 79

A0182 – The thermal behaviour of mono-oxalato-bis-bipyridine-cobalt(III) complexes

The thermal redox decomposition reactions were determined for [Co(bipy)2ox]X. nH2O type coordination compounds (bipy = 2,2'-bipyridine; OX = C2O2-4; X = F-, Cl-, Br-, I-, BIO-4, BF-4, HCOO-, H3CCOO-; n = 0-3). Data were obtained using thermogravimetry and DTA. In the solid phase the thermal reaction pathways were found to be essentially influenced by different anions, X, in the second coordination sphere. The reaction pathways are described and some interpretations of potential reaction mechanisms are proposed.
H. Hennig, K. Jurdeczka and J. Lerchner, Thermochimica Acta 35 (1980) 67-72

A0181 – A vaporization study of Al2Te3

The vapour pressure over solid Al2Te3 has been determined by means of mass-spectrometric, thermobalance, and torsion-effusion techniques in the temperature range 538-760 K. The mass-spectrometric analysis showed that, in the temperature range explored, Te2(g) is the only species present in the vapour. The pressure-temperature dependence of Te2(g) was found to be log P(kPa) = (5.709 ± 0.297) - (8270 ± 152)/T Tellurium seems to vaporize at nearly unit activity and this could be explained by the occurrence of the solid-state reaction Al2Te3(s) = 2/5 Al5Te(s) + 13/5 Te(s) and subsequent vaporization of tellurium to Te2(g). A value of ?H0298(f) = -270.4 ± 21 kJ mole-1 for the heat of formation of Al5Te(s) has been derived.
D. Ferro, B.M. Nappi, G. Balducci and V. Piacente, Thermochimica Acta 35 (1980) 35-41

A0203 – Studies on the thermal decomposition of salicylhydroxamic acid and its metal complexes with Ni(II), Co(II), Fe(II), Mn(II) and Zn(II)

The thermal decomposition of salicylhydroxamic acid and its metal complexes with Ni(II), Co(II), Fe(II), Mn(II) and Zn(II) has been studied by TG, DTG, DTA and IR spectroscopy. All the compounds investigated decompose to yield intermediate N-hydroxylactams. Decomposition schemes have been proposed and reaction enthalpies and kinetic parameters have been calculated.
F. Capitan, D. Gazquez, A. F. Cueto and L. F. Capitan-Vallvey, Thermochimica Acta 75 (1984) 313-321

A0202 – Mo(VI)-oxalate derivatives: thermal behaviour of the [Co(en)3]3+ salts of three different oxoanionic complexes

Molybdenum(VI) dimeric complexes containing an oxo bridge group are long known. Suggestions on the probable existence of doubly bridged(?-oxo-?-hydroxo)dimolybdenum(VI) complex species have been advanced, lacking direct structural confirmation. The study of the thermal behaviour of three different molybdo-oxalate complexes previously described, namely |MoO2(OH)2(C2O4)2|4- and the dimers |Mo2O5(OH)2(C2O4)2|4- and |Mo2O5(OH)(C2O4)2|3-, has provided evidence regarding the existence of significant structural differences between both dimeric species that support the above hypothesis. On the other hand, a new monomeric trioxo species, |MoO3(C2O4)2|4-, has been identified and characterized.
A. Beltran-Porter, E. Martínez-Tamayo, F. Caturla, Thermochimica Acta 75 (1984) 303-311

A0209 – Following photochemical reactions by thermogravimetry

A new thermal analysis system has been designed to follow the influence of light on solid reactants. This method is based upon the association of a thermogravimetric system for the kinetic measuring method, and a U. V. irradiation system for the activation method. This instrument allows comparative studies of a thermal reaction and the corresponding photochemical one under exactly the same experimental conditions. The experiments, carried out in silver carbonate, have provided new information on photochemical kinetics, but also on solid-state reactivity and even on thermal processes. More generally, this device, designed for studies on reactivity, can be applied to any other system needing the action of light. With the device, the influence of the light intensity, the wavelength and the lifetime of light effects on many reactions can be studied.
C. Camus and M. Cournil, Journal of Thermal Analysis 30 (1985) 17-24

A0208 – Thermal studies on beryllium, magnesium and calcium hafnyl oxalates

Beryllium hafnyl oxalate tetrahydrate, magnesium hafnyl oxalate tetrahydrate and calcium hafnyl oxalate tetrahydrate abbreviated as BHO, MHO and CHO, respectively, have been prepared in an aqueous medium and characterized by elemental analysis, magnetic susceptibility measurements and infrared spectral data. The thermal behaviour of these compounds in non-isothermal conditions have been investigated by employing TG, DTG and DSC techniques. The intermediates obtained at the end of various thermal decomposition steps were identified on the basis of elemental analysis and infrared spectral studies. The graphical method of Coats and Redfern has been employed to evaluate the kinetic parameters such as apparent activation energy and order of reaction. Heat of reaction for different decomposition steps have been calculated from the DSC curves.
O.P. Pandey, S.K. Sengupta and S.C. Tripathi, Thermochimica Acta 103 (1986) 239-245

A0208 – Thermal studies on beryllium, magnesium and calcium hafnyl oxalates

Beryllium hafnyl oxalate tetrahydrate, magnesium hafnyl oxalate tetrahydrate and calcium hafnyl oxalate tetrahydrate abbreviated as BHO, MHO and CHO, respectively, have been prepared in an aqueous medium and characterized by elemental analysis, magnetic susceptibility measurements and infrared spectral data. The thermal behaviour of these compounds in non-isothermal conditions have been investigated by employing TG, DTG and DSC techniques. The intermediates obtained at the end of various thermal decomposition steps were identified on the basis of elemental analysis and infrared spectral studies. The graphical method of Coats and Redfern has been employed to evaluate the kinetic parameters such as apparent activation energy and order of reaction. Heat of reaction for different decomposition steps have been calculated from the DSC curves.
O.P. Pandey, S.K. Sengupta and S.C. Tripathi, Thermochimica Acta 103 (1986) 239-245

A0207 – Thermal studies of tin (II) and tin (IV) dihydroxyphenolates

The thermal behaviour of tin(II) and tin(IV) compounds with 2,3-dihydroxynaphthalene and pyrogallol was studied by thermogravimetry (TG) and differential thermal analysis (DTA). All the compounds decompose in several steps, with partial elimination of ligand, elimination of the remaining ligand and SnO2 residue formation.
L. Soto-Tuero, E. Martinez-Tamayo, L. Perello and J. Borras, Thermochimica Acta 97 (1986) 257-260

A0206 – La prévision des incendies de foret

J.C. Drouet, Revue Sécurité, 5,24 (1981)

A0206 – La prévision des incendies de foret

J.C. Drouet, Revue Sécurité, 5,24 (1981)

A0205 – Characterization of catalytic surfaces by a novel kinetic adsoption technique

H. Fleming, ALCOA, Pittsburgh (U.S.A.)

A0211 – Dégradation thermique de poly-a-acetoxystyrènes para-substitués

Une étude cinétique de la décomposition thermique globale de deux poly-alpha-acétoxystyrènes para-substitués (R = CH3, Cl) a été entreprise. La réaction peut être considérée comme étant d'ordre 1 dans un large domaine de perte de masse. L'énergie d'activation est alors de 42 kcal mol-1 pour R = CH3 et de 48 kcal mol-1 pour R = Cl. Les résidus solides ont déjà été identifiés comme étant des polyphénylacétylènes para-substitués de masse molaire relativement faible. Les composés volatils ont été identifiés par CPG-MS comme étant, essentiellement, l'acide acétique, l'anhydride acétique, l'acétophénone para-substituée et le monomère. La réaction de décomposition thermique est donc vraisemblablement la superposition de deux réactions: la perte d'acide acétique et la dépolymérisation partielle. Un mécanisme est proposé.
B. Boinon, M.J. Boinon and J.P. Montheard, Thermochimica Acta 87 (1985) 289-296

A0211 – Dégradation thermique de poly-a-acetoxystyrènes para-substitués

Une étude cinétique de la décomposition thermique globale de deux poly-alpha-acétoxystyrènes para-substitués (R = CH3, Cl) a été entreprise. La réaction peut être considérée comme étant d'ordre 1 dans un large domaine de perte de masse. L'énergie d'activation est alors de 42 kcal mol-1 pour R = CH3 et de 48 kcal mol-1 pour R = Cl. Les résidus solides ont déjà été identifiés comme étant des polyphénylacétylènes para-substitués de masse molaire relativement faible. Les composés volatils ont été identifiés par CPG-MS comme étant, essentiellement, l'acide acétique, l'anhydride acétique, l'acétophénone para-substituée et le monomère. La réaction de décomposition thermique est donc vraisemblablement la superposition de deux réactions: la perte d'acide acétique et la dépolymérisation partielle. Un mécanisme est proposé.
B. Boinon, M.J. Boinon and J.P. Montheard, Thermochimica Acta 87 (1985) 289-296

A0210 – Thermal studies on organomercury(II) complexes of 6-amino penicillinic acid

Organomercury(II) derivatives of 6-amino penicillinic acid (A) of the type RHgL (B) (R = phenyl (C6H5), p-acetoxyphenyl (p-CH3COOC6H4), p-hydroxyphenyl (p-HOC6H4); HL = 6-amino penicillinic acid) have been synthesised. Spectral studies (IR and UV) indicate that the penicillin moiety is bidentate. From thermogravimetric curves, the order and activation energy of the thermal decomposition reaction have been elucidated. The variation of activation energy has been co-related with the nature of substituent on the phenyl ring. The thermal decomposition reaction in each case follows an F1 type mechanism. From differential thermal analysis the activation energy and the heat of transition for thermal effects have been calculated. The fragmentation pattern has been analysed on the basis of mass spectra.
S. Kamrah, G.S. Sodhi and N.K. Kaushik, Thermochimica Acta 87 (1985) 203-209

A0213 – Etude de quelques benzoates de cuivre (II) solvates

La préparation de complexes du benzoate de cuivre(II) avec l'imidazole ou ses dérivés méthylés a été réalisée. Les complexes obtenus ont été étudiés par TG, ATD, RPE et réflectance diffuse. L'étude de leur stabilité thermique nous a conduit à un intermédiaire déjà mis en évidence lors de la décomposition d'autres composés. D'autre part, les spectres de réflectance diffuse permettent de penser que nos composés sont octaédriques et les valeurs du paramètre de covalence sont du même ordre que celles déterminées par d'autres auteurs.
M.A. Bernard, A. Busnot, F. Busnot and J.F. Le Querler, Thermochimica Acta 146 (1989) 39-52

A0212 – Caractérisation des tripolyphosphates mixtes d’ammonium et de terres rares NH4LnHP3O10 (Ln=Nd,Ho,Er)

Trois tripolyphosphates NH4NdHP3O10, NH4HoHP3O10, NH4ErHP3O10 sont isolés pour la première fois. Ils cristallisent dans le groupe d'espace P avec Z = 2. Leurs paramètres de maille sont: a = 7,04 (1) Å, b = 7,72 (1) Å, c = 8,64 (1) Å, alpha =106,4 (1)°, beta = 106,0 (1)°, gamma = 82,6 (2)° pour NH4NdHP3O10; a = 7,03 (2) Å, b = 7,67 (2) Å, c = 8,66 (3) Å, alpha = 106,3 (3)°, beta = 105,8 (3)°, gamma = 82,5 (4)° pour NH4HoHP3O10 et a = 6,96 (4) Å, b = 7,68 (3) Å, c = 8,69 (3) Å, alpha = 106,3 (4)°, beta = 105,8 (4)°, gamma = 82,5 (4)° pour NH4ErHP3O10. Ces trois phosphates condensés sont caractérisés par leurs spectres de diffraction des rayons X de poudre, leurs spectres d'absorption IR et leurs courbes d'analyse thermique ATD. Ces trois phases sont isotypes avec NH4BiHP3O10.
M. Ferid, N. Kbir-Ariguib, M. Trabelsi-Ayedi, Thermochimica Acta 147 (1989) 241-249

A0215 – Etude de quelques propionates de cuivre (II) solvates

Un certain nombre de complexes du propionate de cuivre solvaté par l'imidazole ou ses dérivés méthylés ont été préparés. Une étude par RPE et par réflectance diffuse a été menée qui a conduit a mettre en évidence le caractére dimére du complexe obtenu avec le méthyl 1 imidazole. La valeur k02 caractéristique du degré de covalence de la liaison cuivre-ligand a été déterminée et les valeurs trouvées pour les différents complexes sont du même ordre de grandeur que celles calculées par Yokoi et al. (Bull. Chem. Soc. Jpn., 45 (1972) 2189) pour les complexes des amino-acides du cuivre(II).
M.A. Bernard, A. Busnot, F. Busnot, J.F. Le Querler, J.F. Hemidy, Thermochimica Acta 145 (1989) 139-148

A0214 – Thermal decomposition and reduction with H2 and C2H4 of silver (I,II) oxide.

Two types of AgO (monoclinic and tetragonal) have been studied by thermogravimetry. The thermal decomposition of AgO to AgO2 proceeds according to a nucleation-growth mechanism, A2. The introduction of nuclei of Ag2O modifies the mechanism to a propagation law, R3, but only when the nuclei are made by thermal decomposition. The reduction of AgO with hydrogen gives silver in one step, but with ethylene the reduction proceeds in two steps, with the intermediate formation of Ag2O.
P. Tissot, H. Lartigue and J.F. Rossignol, Thermochimica Acta 162 (1990) 435-444

A0217 – Pirolisis de lignitos : estudio cinetico

J.F. Perales, T. Coll, J. Arnaldos, J. Casal, M.F. Llop, J. Puigjaner

A0216 – Synthesis of 80 K superconducting YBa2Cu4O8 via a novel route.

The YBa2Cu4O8 ("124") superconductor with transition temperature at 80 K is synthesized via a solid state reaction for 1 h at 800°C in flowing oxygen with a total pressure of about 2.7 X 102 Pa, followed by cooling and annealing in oxygen at ambient pressure for 20 h at 750°C. This procedure has produced orthorhombic 124 as the main phase with YBa2Cu3Ox ("123") as a minor impurity phase. Annealing the as-calcined powder in flowing oxygen at 800°C for 24 h under ambient pressure improved the phase purity and nearly phase-pure 124, determined by X-ray diffraction and magnetization measurements, has been obtained.
U. Balachandran, M.E. Biznek, G.W. Tomlins, B.W. Veal and R.B. Poeppel, Physica C : Superconductivity 165 (1990) 335-339

A0218 – Thermal study of some transition metal complexes of N(-ETHYL, m-TOLYL) dithiocarbamic acid

S. Kumar, N.K. Kaushik, I.P. Mittal, ICTA (1980) 137-146

A0220 – Dégradation thermique des trois isomères : Ortho, Meta, Para du polymethoxymethylstyrene

Une étude cinétique de la réaction globale de dégradation thermique des trois isomères ortho, méta et para du polymethoxyméthylstyréne a été entreprise. Il n'y a pas d'ordre apparent pour l'isomère ortho, alors que l'ordre apparent est un pour les isomères méta et para, dans un large domaine de perte de masse. Pour ces derniers, les énergies d'activation sont respectivement de 32,5 et 31 kcal mol-1. Les composés volatils, identifiés par Chromatographie en phase gazeuse couplée à la spectrométrie de masse, sont constitués essentiellement de monomères. La réaction est donc essentiellement une réaction de dépolymérisation, associée à des réactions de pontages interchaînes pour les polyméres méta et para.
B. Boinon, D. Ainad-Tabet and J.P. Montheard, Thermochimica Acta 112 (1987) 325-334

A0219 – High temperature CO2 decomposition of the YBa(2)Cu(3)O(7-x) superconductor.

J.J. Simmins, P.H. McCluskey, G.S. Fischman, R.L. Snyder, 91st Annual Meeting of the American Ceramic Society, Indianapolis (1989) 1-13

A0222 – Equipment for studying hot corrosion processes in dynamic gas mixtures containing water vapour.

A Setaram unit including a symmetric oven and a MTB 10/8 microbalance was chosen as a base equipment in order to reduce the impulse variations frequently occurring in dynamic regimes. The thermobalance and its surroundings were thoroughly thermostated owing to water vapour. To pull up and let down the sample quickly without damage for the torsion strip, a telehandling airtight apparatus with visual control has been worked out, allowing to make optional the connection between the suspension chain and the microbalance beam. The equipment here described has been conceived for hot corrosion kinetic studies (round 1000°C) concerning low weight samples (10-100mg) in such gaseous flows as X/H2O containing air, oxygen and hydrogen in the presence of water vapour (1-75 %).
P. Raynaud, F. Nardou and M. Billy, Thermochimica Acta 103 (1986) 27-32

A0221 – Study of the thermal behaviour of ordered bimetallic EDTA complexes

The study of the thermal behaviour of a family of isostructural ordered bimetallic MM'(EDTA).6H2O complexes has been performed using TG and DTA. Formal kinetic analysis of the dehydration step has been approached using non-isothermal procedures. The resulting correlation among the calculated Ea values and the cationic sizes implies a common dehydration mechanism. Copper-containing complexes show distinctive behaviour during the ligand pyrolysis processes. A mechanistic interpretation involving formation of Cu(I) and Cu(0) intermediates is furnished. The evolution of the inorganic residues in systems containing both Co and Ni is especially considered given the interest in the (CoxNi1-x)1-y)O system.
E. Escriva, A. Fuertes, J.V. Folgado, E. Martínez-Tamayo, A. Beltran-Porter and D. Beltran-Porter, Thermochimica Acta 104 (1986) 223-245

A0224 – Etude de la décomposition thermique des polyhétéroarylènes

An investigation was made of the thermal and thermooxidative decompositions of polybenzimidazopyrrolones and polybenzimidazobenzoquinolines, as well as a number of heterocyclic compounds modelling the linkages and individual fragments of these polymers. It was established that in the pyrolyses of the polyheteroarylenes and the corresponding model compounds the destruction of cycles occurs either simultaneously with cleveage of the Car--H bond or at a higher temperature. It was shown that the completely aromatic compounds and the heterocyclic compounds condensed with the benzene nucleus are the most therrnostable of the investigated compounds. A comparative study revealed a correlation between the structures and thermal stabilities of the studied compounds.
D.M. Mognonov, J. Varga, A.I. Batotsyrénova, V.G. Samsonova et A.A. Izynéev, Journal of Thermal Analysis 30 (1985 ) 1053-1062

A0223 – Studies of interfacial properties in polyepoxyde/carbon or glass fiber composites by means of microgravimetric techniques

The microweighing techniques have been chosen to analyze the interface problem of composite materials with polyepoxyde matrix and fibrous reinforcement, particularly the surface interactions and the wetting of carbon and glass fibers with some reactive groups of the organic matrix. The experimental data deal with the nature and energy of interactions, the hydrophilic or hydrophobic behaviour of the surfaces, the wetting angle. The surface of the fibers is modified by various treatments : oxidation, laying of a coating agent. The results allow to make propositions on the role of these treatments during the making of the composite and they also allow to analyze the differences between carbon and glass behaviour.
M. Escoubes, B. Chabert and D. Sage, Thermochimica Acta 103 (1986) 97-106

A0226 – Effects of the working conditions on the values of the kinetic parameters of the thermal decompositions of some complexes

The kinetic parameters n, A and E (the order of the decomposition reaction, the preexponential factor and the activation energy of the thermal decompositions) of some complexes of general formula [MC12(GTD)2]CI, where GTD = Girard T-diacetylmonoxime cation and M - central metal ion = Mn(lI), Fe(III) and Co(ll), were calculated through their TG curves. The effects of working conditions such as the sample weight and the rate of heating on the evaluated kinetic parameters are discussed.
M.E.M. Emam, Journal of Thermal Analysis 35 (1989) 775-779

A0225 – Thermochemistry of coal oxidation.

Five types of Polish bituminous coal of different grades were analysed using, simultaneously, thermogravimetric analysis (TGA), differential thermogravimetry (DTG), differential thermal analysis (DTA) and evolving gas analysis (EGA) to investigate the non-isothermal coal oxidation. The TGA, DTG and DTA curves, together with EGA, provided parameters which characterize the tendency of a given coal towards oxidation. The TGA and EGA parameters can also be used to approximate the specific active surface area of coal in reaction with oxygen. Due to the negative effects of coal oxidation, such as self-oxidation, an inhibitor was proposed and tested by analysis of the above specified thermoanalytical curves and EGA.
M.S. Matyjaszczyk, R. Przeliorz, Thermochimica Acta 96 (1985) 169-187

A0229 – Etude de la stabilité thermique du poly(styrène covinyl benzyl diethyl phosphonate)

La copolymérisation du styrène et du vinyl benzyl diéthyl phosphonate permet d'obtenir un produit qui comporte environ 15% de groupes aromatiques phosphorés. Le produit a été caractérisé par GPC (w = 560000 et n = 110000), RMN et l'étude de sa stabilité thermique a été entreprise. La première étape de la dégradation commence à 300°C et se termine vers 375°C, elle est probablement due à des impuretés ou à des produits de faibles masses. La deuxième étape débute à 400°C et se termine vers 500°C. Il s'agit essentiellement d'une réaction de dépolymérisation. L'énergie d'activation est de 44 kcal mol-1. L'incorporation de groupes phosphonates permet d'augmenter la stabilité du polymère comparativement à celle du polystyrène.
B. Boinon, B. Benayad and J.P. Montheard, Thermochimica Acta 117 (1987) 177-185

A0228 – Cu(II) phenobarbiturates and N-Methyl phenobarbiturates. Thermal decomposition processes

The thermal behaviour of complexes of phenobarbiturate and N-methylphenobarbiturate with Cu(II) was studied by thermogravimetry (TG) and differential thermal analysis (DTA). The complexes decompose in two steps: dehydration and decomposition of the anhydrous complex to metal oxides and carbonates. The activation energies of dehydration processes were determined and we can conclude that the water molecules interact weakly with the metallic ion.
A. Jiménez, H. Jiménez and J. Borras, Thermochimica Acta 117 (1987) 135-138

A0227 – Correlation of thermal stability with structures for some metal complexes

Thermogravimetric studies have been carried out for a number of complexes of the type MCu(dtc)4[dtc = N-ethylcyclohexyldithiocarbamate (I); M = Zn(II), Cd(II), Hg(II)], (?5-C5H5)2M'Cl(L)(II) [L = benzylpenicillin; M' = Ti(IV), Zr(IV)] and [(?5-R)2M'L']+ [dtz]-(III) [HL' = oxine; dtz - phenyldithiocarbazate (C6H5NHNHCS2); R = cyclopentadienyl (C5H5), indenyl (C9H7)]. From TG curves, the order and apparent activation energy for the thermal decomposition reaction have been elucidated, and the various thermal stabilities have been correlated with some structural aspects of the complexes concerned.
G.S. Sodhi, Thermochimica Acta 120 (1987) 107-114

A0232 – Study of temperature-programmed desorption of tert butylamine to measure the surface acidity of solid catalysts

The technique of temperature-programmed desorption of tert-butylamine is described to measure the surface acidity of solid catalysts. The use of this base has advantages over the use of ammonia, pyridine, and n-butylamine. The desorption measurement is carried out by two methods, gas chromatography and thermogravimetry, and the advised conditions are described for both methods. Catalysts of SiO[2]/Al[2]O[3], bifunctionals of Ni-SiO[2]/Al[2]O[3], and a commercial cracking zeolite have been studied. A comparison of the desorption results with those of the other acidity measurement techniques (such as titration with n-butylamine in the liquid phase and kinetic measurement of isomerization of n-butenes as the test reaction) allows the actidity measured with tert-butylamine desorption to be classified as strong, corresponding to the active sites in most of the reactions among the hydrocarbon compounds catalyzed by acids
A.T. Aguayo, J.M. Arandes, M. Olazar, J. Bilbao, Industrial & Engineering Chemistry Research 29 (1990) 1621-1626

A0231 – Etude thermolytique et polymorphique des composés KCaPO4.H2O et K4Ca(PO4)2.5H2O

Les composés KCaPO4. H2O et K4Ca(PO4)2.5H2O ont été étudiés par analyses thermogravimétrique et thermique différentielle. Les spectres de diffraction X et d'absorption IR du pentahydrate et de l'anhydre correspondant sont donnés. La déshydratation de KCaPO4. H2O s'effectue en une seule étape. Le sel anhydre KCaPO4 présente une transformation polymorphique. La déshydratation de K4Ca(PO4)2. 5H2O s'effectue en cinq étapes mettant en évidence les sous-hydrates à 3, 2, 1,5 et 1 H2O. Le sel anhydre K4Ca(PO4)2 présente trois transformations polymorphiques à 640°C, 715°Cet 1010°C.
R. Rokbani and N. Kbir-Ariguib, Thermochimica Acta 159 (1990) 201-214

A0230 – Thermoanalytical characterization (DTA and TG)of RBa(2)Cu(3)O(7-x) (R= Y, Gd, Nd) superconductors

Differential thermal analysis (DTA) and thermogravimetric (TG) analysis were used to characterize RBa2Cu3O7-x (R Y, Gd, Nd) superconductors. Even if the resistivity-temperature curves are similar for the three compounds, DTA shows that the behavior of these materials during synthesis and sintering is different. Of the three systems, the Nd-Ba-Cu-O system is the most favorable for the formation of the 123 superconductor because secondary phases are present in smaller quantities. TG curves suggest the presence of a transition from the orthorhombic phase to the tetragonal phase in a nitrogen atmosphere at about 550-600°C for the three perovskites. The energy required to insert oxygen atoms in the crystal structure is smaller for the neodymium and gadolinium compounds than for the yttrium compound (Gd < Nd < Y). There is also a proportional relation between the ionic radius of the rare earth element and the onset melting temperature.
D. Noël and L. Parent, Thermochimica Acta 147 (1989) 109-117

A0233 – Etude de la dégradation thermique de gels de borosilicate et borogermanate de cadmium et caractérisation des vitrocéramiques obtenues

W. Granier, J.C. Kayi-Maoumoucka, D. Cachau, JCAT (1991) 273-280

A0235 – Etude thermogravimétrique de l’adsorption de l’eau sur quelques oxydes métalliques

F. Gruy, M. Pijolat, M. Prin, M. Soustelle, JCAT (1991) 329-336

A0234 – Réactivité du système métaphosphate de sodium/oxydes métalliques suivie par analyse thermique

L. Montagne, B. Deffontaines, P. Vast, G. Palavit, JCAT (1991) 305-311

A0238 – Some aspects of the preparation, characterization and thermal decomposition of anisaldehyde girard T complexes of some transition elements

Anisaldehyde Girard T complexes of Mn(II), Fe(III), Co(II) and Cu(II) with the general formula [MCI2(AGT)2]CI2 or [MCI2(AGT)]CI, where (AGT)--anisaldehyde carbohydrazone methyltrimethylammonium cation, H3C-- O -- C6H4-- CH = N- NHCOCH2N+-(CH3)3 and M= Mn(II), Co(II), Fe(III) or Cu(II) were prepared. Elemental analysis, electrical conductance and IR spectra showed that the ligand coordinates with the studied metals in keto form through the azomethine and carbonyl groups. The molar conductances, electronic spectra and magnetic moments of the solid complexes were determined. The processes of thermal decomposition of these complexes were studied. From the analysis of the thermal decomposition curves obtained, the corresponding kinetic parameters n, Ea and logA were evaluated by two different methods and the effects of the central metal ions on the stabilities of the complexes are discussed.
M.E.M. Emam, M.A.H. Hafez and M.N.H. Moussa, Journal of Thermal Analysis 37 (1991) 1005-1013

A0237 – Thermal decomposition of cellulose hyphan and its complexes with rare earth elements and scandium

Thermal decomposition of cellulose hyphan (CH) and its complexes with Lu, Gd, Nd and Se under an atmosphere of air has been studied using thermogravimetry (TG~differential thermogravimetry (DTG) and differential thermal analysis (DTA). The results showed that, a different stages are accompanying the decomposition of (CH) and its complexes. These stages are affected by the presence of the metal ions. On the basis of the applicability of a non-isothermal kinetic equation, it was demonstrated that three main stages are involved in the decomposition processes. The activation energies of the different stages are calculated.
A.A. Said and I.M. Kenawy, Journal of Thermal Analysis 36 (1990) 1257-1264

A0236 – Thermoanalytical characterization (DTA and TG) of RBa(1.5)Sr(0.5)Cu(3)O(7-x) and RBaSrCu(3)O(7-x) (R=Y,Gd,Sm or Nd) superconductors

Differential thermal analysis and thermogravimetric analysis were used to characterize RBa1.5Sr0.5Cu3O7-x and RBaSrCu3O7-x superconductors (R=Y, Gd, Sm or Nd). It was found that the replacement of Ba by Sr increases the onset melting temperature of the perovskites. The effect is larger for compounds which contain an R atom with a small ionic radius. TG curves show that the temperature of the orthorhombic-tetragonal transition is modified by the presence of Sr.
D. Noël and L. Parent, Thermochimica Acta 171 (1990) 57-65

A0240 – Thermal studies on organomercury (II) complexes of 6-thioguanine

Organomercury(II) complexes involving 6-thioguanine of the typep-XC6H4HgL (I) (LH = 6-thioguanine; X = Me, MeO, NO2) have been synthesized. Spectral studies (IR and UV) indicate that the 6-thioguanine moiety acts as a bidentate group. From thermogravimetric (TG) curves, the order, activation energy and apparent activation entropy of the thermal decomposition reaction have been elucidated. The variation of the activation energy has been correlated with the nature of the substituent on the phenyl ring. The heat of reaction has been obtained from differential scanning calorimetric (DSC) studies.
V.K. Ahluwalia, J. Kaur, B.S. Ahuja and G.S. Sodhi, Thermochimica Acta 176 (1991) 321-325

A0239 – Thermal behaviour of ammonium dihydrogen phosphate crystals in the temperature range 25-600°C

A slow evaporation technique was used to grow single crystals of ammonium dihydrogen phosphate (ADP) from supersaturated aqueous solutions An identification of crystal structure for as-grown ADP crystals was achieved Simultaneous TG, DTG and DTA showed that the ADP crystals decompose at 210°C to orthophosphoric acid with evolution of ammonia The orthophosphoric acid converts to pyrophosphoric acid and then to metaphosphonc acid. A pronounced resolution of the overlap between phase transition, melting and decomposition of ADP crystals was obtained at relatively high heating rates. Differential scanning calorimetry (DSC) confirmed the phase transition in ADP crystals at 175°C Kissinger and Ozawa methods were applied to calculate the activation energies for the thermal processes occurring at 210°C, which are 90.37 kJ mol-1 and 99.12 kJ mol-1 respectively. The phase transitions and thermal decompositions of ADP crystals have been confirmed by X-ray diffraction and infrared absorption spectra.
A. Abdel-Kader, A.A. Ammar and S.I. Saleh, Thermochimica Acta 176 (1991) 293-304

A0243 – A new master plot using the differential method in kinetic analysis of non-isothermal TG data

A new master plot developed from the differential method is proposed, which can give information about the reaction mechanism and the activation energy simultaneously from non-isothermal TG data. The applicability of the master plot is confirmed by comparing the results of kinetic analysis with those published for the thermal decomposition of CaCO3 in an air atmosphere. The results are in good agreement with those previously published.
E.H. Kim, J.J. Park, J.H. Park, I.S. Chang and C.S. Choi, Thermochimica Acta 196 (1992) 495-502

A0242 – Characterization of a cerium dioxide powder from its equilibrium with water vapour

The equilibrium between water and a cerium dioxide powder was studied by means of thermogravimetry between 373 and 573 K. The isotherms can be interpreted by the additive contribution of water adsorbed on two distinct sites which differ in their standard enthalpy of fixation and their relative population. The results agree with the model water is fixed on the ceria surface through direct bonds to cerium atoms and by hydrogen bonding to hydroxyl groups located in the micropores. The latter sites disappear following calcination at high temperature. This is confirmed by transmission electron microscopy photographs and nitrogen adsorption measurements.
M. Prin, M. Pijolat, M. Soustelle and O. Touret, Thermochimica Acta 186 (1991) 273-283

A0241 – Thermal stability and reactivity in oxygen of potassium ferrites with spinel structure

The potassium content really incorporated in the spinel lattice of the magnetite determined by thermogravimetric analysis in vacuum or in oxygen was about 2.45 wt%. In spite of this low content, the potassium strongly stabilises the defect spinel structure resulted by the potassium-substituted magnetite oxidation and increases the transformation temperature of the defect phases into alpha-Fe203 or KFe11017.
B. GilIot, M. Laarj, B. Maachi and A. Rousset, Journal of Thermal Analysis 36 (1990) 645-656

A0244 – Uso de la termogravimetria para la caracterizacion y determinacion de parametros cineticos de catalizadores solidos

A. Guayo, Dpto, Ingenieria Quimica, Universidad del Pais Vasco, Curso de termogravimetria y analisis térmicos

A0247 – Coal pyrolysis : thermogravimetric study and kinetic modelling

In this experimental study on coal pyrolysis it was found that heat transfer and heating rate have an important influence on the results obtained. A model has been developed which takes into account these aspects. The kinetic parameters were determined using a differential method and the experimental data obtained at low heating rates. The agreement between the predictions of the model, for any heating rate, and the experimental values is fairly good.
T. Coll, J.F. Perales, J. Arnaldos and J. Casal, Thermochimica Acta 196 (1992) 53-62

A0246 – Thermoanalytical investigations on the decomposition of double salts. III. The decomposition of double salts MBr.MgBr2.6H2O

The melting and decomposition behaviour of the double salts MBr'MgBrz'6H20 (M = K, NH4, Rb, Cs) has been investigated in a closed system under dynamic and quasi-isothermal and quasi-isobaric conditions between 20°C and 300°C or 600°C, respectively. DTA heating and cooling cycles illustrate the melting behaviour of the double salts and give information on the melting point of these substances. The thermal decomposition of double salts under quasi-isothermal and quasi-isobaric conditions takes place in the melt (with the exception of RbBr.MgBrz'6H20) and under reduced pressure in the solid phase. A double salt of the type MBr-MgBrz-6H20 is formed as a stable intermediate. The final product of all types of thermal decomposition are basic products with different hydroxide or oxide contents, respectively.
H.H. Emons, H. Voigt, R. Naumann and T. Pohl, Journal of Thermal Analysis 37 (1991) 1605-1619

A0245 – Thermal features and behaviour of some heptamolybdates of mononitrogen aliphatic bases

The thermal behaviour of heptamolybdates of n-alkylammonium with general formula [(CnH2n+l)NH3][MovO24].3H20, where n = 4-6, has been studied by thermoanalytical methods (DTA, TG and DTG) under argon-oxygen and argon atmospheres. It has been found that the surrounding atmosphere is an important factor which significantly influences the course of the decomposition reaction as well as the final product. In the presence of oxygen all the compounds undergo decomposition upon heating, leading to MoO3 above 520°C. Thermogravimetric curves indicate that compounds decompose in a great number of stages and the pathway is not simple, therefore only the whole process can be described. The thermal behaviour in an inert argon atmosphere is quite different and the final solid residues at 600°C contain carbon. The essential thermal characteristics, as well as the influence of the crystal structure of the alkylammonium heptamolybdates on their thermal behaviour are also reviewed and discussed.
P. Roman, A. Luque, A. Aranzabe and C. Guzman-Miralles, Thermochimica Acta 197 (1992) 69-78

A0251 – Computer kinetic analysis of thermoanalytical data

A program has been worked out to provide kinetic analysis of non-isothermal data. To evaluate the kinetic parameters the main procedure uses the integral method of exponential multipliers (IMEM). TG and DTA curves have been recorded with a Setaram TAG 24S24 thermoanalyser. The program has been tested for dehydration of CaC2O4.H2O. Also it has been applied to the kinetic study of copper oxidation with barium peroxide and oxygen thermodesorption in YBa2Cu3O6.9±0.1 superconductor.
A.N. Peregudov, T.V. Peregudova and L.G. Karpov, Thermochimica Acta 197 (1992) 21-26

A0250 – Réactivité suivie par analyse thermique de précurseurs colloidaux de céramiques phosphatées dans le système CaO-Na2O-P2O5-TiO2 (anatase)

M. Deffontaines-Fourez, B. Deffontaines, P. Vast, JCAT (1992) 105-112

A0248 – Quelques apports de l’analyse thermique différentielle à l’étude de l’élaboration de métaux, composites, intermétalliques à partir de poudres

Y. Bienvenu, JCAT (1992) 157-164

A0254 – Thermal behaviour and properties of n-alkylammonium decavanadates

The thermal behaviour of three n-alkylammonium decavanadates with the general formula [(CnH2n+1)NH3IV10O28].2H2O where n = 4-6, has been studied by thermogravimetry (TG and DTG) and differential thermal analysis (DTA) under argon-oxygen and argon atmospheres from room temperature to 600°C. The surrounding atmosphere is an important factor which significantly influences the course of the decomposition reaction and the final products. In an argon-oxygen atmosphere the compounds lose two water molecules during a first endothermic step to give a stable anhydrous compound. A relationship has been found between the density values of the compounds and the dehydration temperature range. The anhydrous compounds decompose via several oxidative exothermic processes to give vanadium(V) oxide. No other stable products were found during the thermal decomposition owing to the overlap of these last oxidative processes. The thermal decompositions in an argon atmosphere begin with a similar dehydration step for the three compounds followed by a progressive weight loss. The final products at 600°C in an inert atmosphere were identified by X-ray powder diffraction data as mixtures of vanadium(IV) and vanadiumd(III) oxides. The essential thermal features, as well as the influence of the crystal structure of the n-alkylammonium decavanadates on their thermal behaviour, are also reviewed and discussed.
P. Roman, A. Aranzabe and A. Luque, Thermochimica Acta 206 (1992) 61-69

A0253 – Synthesis, solid state characterization and thermal behaviour of some t-butylammonium polymolybdates

During a study of the reaction between MoO3 and t-butylamine in aqueous solution, using different amounts of reactants and pH conditions, three new polymolybdates of t-butylammonium were isolated: (BH)2[MoO4] (TBUTMO1), (BH)6[Mo7O24].7H2O (TBUTMO7) and (BH)4[Mo8O26].6H2O (TBUTMO8), where B = t-butylamine. These compounds were characterized by means of chemical analysis and thermal and FT-IR techniques. Thermal decomposition studies were carried out using TG, DTA and DTG techniques under argon-oxygen and argon atmospheres. Final products of the thermal decompositions were analysed by elemental analysis and the X-ray powder diffraction technique. The results show that the thermal behaviour of these compounds is extremely sensitive to the presence of oxygen in the surrounding atmosphere. Under an argon-oxygen atmosphere the thermal decompositions lead to a final solid residue above 300-450°C, identified as Mo03 by FT-IR spectral and X-ray powder diffraction data. In an argon atmosphere, all the decomposition processes are endothermic, and the final weight losses are rather different from that expected for molybdenum trioxide. Final residues for TBUTMO1 and TBUTMO7 comprise a mixture of molybdenum(IV) oxide and amorphous compounds containing carbon. The elemental analysis of the final black X-ray amorphous product from TBUTMO8 gave an indication of carbon in its composition.
P. Roman, A. San José, A. Aranzabe and A. Luque, Thermochimica Acta 206 (1992) 137-147

A0252 – Synthetic reversible oxygen- or nitrogen-carrying chelates of nickel (II)

New oxygenated complexes of nickel(II) with the composition Ni2O4(Imid)xAy. zNH3 or Ni2N4(Imid)x'Ay'. z'NH3, where Imid represents the imidazole molecule and A the anion of succinic acid, maleic acid or glutaric acid, have been synthesized. The behavior of these salts when heated in air has been studied by thermogravimetric methods and it has been established that in all cases the product of the decomposition is the oxide or the carbonate. Diffuse reflectance spectra are presented. Calculated electronic transitions are in good agreement with those observed. It seems that the nickel ions are in an octahedral environment.
A. Busnot, J.F. Le Querler and J. Yazbeck, Thermochimica Acta 197 (1992) 443-451

A0255 – Study by electrical conductivity, derivative thermogravimetry, infrared spectrometry and X-ray photoelectron spectroscopy of oxidation process of Fe2MoO4 in relation to the cationic distribution

The thermal behaviour in oxygen of Fe2MoO4 spinel prepared by the ceramic method has been investigated over the temperature range of 150-700°C on ground samples. Below 550°C, Fe2MoO4 is partially oxidized in the cation deficient spinel with a very large content of vacancies. The high electrical conductivity of the initial sample and its temperature dependence in oxygen can be related to a mixture of Fe2+ and Fe3+ valencies on both octahedral (B) and tetrahedral (A) sites, despite the observed positive value of the Seebeck coefficient. Derivative thermogravimetric studies showed that B site Fe2+ and Mo3+ ions will be oxidized more rapidly than A site Fe2+ ions when the oxidation temperature is lower for Fe2+ ions on B sites than that for Mo3+ ions on the same sites, and this discrepancy in reactivity has been used to determine the distribution of cations between the sublattices. In addition, a significant content of Mo4+ ions and a transfer of Mo6+ ions from the B sites to the A sites during oxidation can be derived from XPS and IR spectrometry.
B. Domenichini, B. Gillot, P. Tailhades, Thermochimica Acta 205 (1992) 259-269

A0257 – Physicochemical characterization of cholesterol-beta cyclodextrin inclusion complexes

Study and characterization of molecular complexes between cholesterol and beta cyclodextrin has been done using X-ray diffraction, thermogravimetric analysis (TG), differential scanning calorimetry (DSC) and nuclear magnetic resonance spectroscopy (a3C NMR). Whatever the value of the molar ratio cholesterol/flCD used during the preparation, the same compound is always obtained. Corresponding to a molar ratio 1/3 (cholesterol/- flCD), this compound is a stable hydrate which, contrary to flCD, contains at room temperature a large amount of molecules of water. It can be dehydrated under low pressure but the thermal degradation occurs at 200~ (250~ for flCD). This implies that cholesterol is strongly bounded to flCD.
P. Claudy, J.M. Létoffé, P. Germain, J.P. Bastide, A. Bayol, S. Blasquez, R.C. Rao and B. Gonzalez, Journal of Thermal Analvsis 37 (1991) 2497-2506

A0256 – Thermal and magnetic studies of mixed ligand complexes of chromium (III) containing dithiocarbamate and acetylacetone/oxide/glycine moieties

Chromium(III) complexes of the type Cr(A)(A')2, Cr(A)2(A') and Cr(A)3 have been prepared (where A is either piperidyldithiocarbamate or morpholyldithiocarbamate and A' is glycine or oxine or acetylacetone moiety). The mixed ligand complexes have been characterized by elemental analyses, magnetic susceptibility measurements and thermal studies. The complexes show magnetic moment in the range of 3.5-4.3 B.M. which corresponds to three unpaired electrons. TG studies have also been carried out, in order to study the mode of decomposition of the complexes and to evaluate various kinetic parameters.
B.S. Garg, R. Dixit, A.L. Singh and R.K. Sharma, Journal of Thermal Analysis 37 (1991) 2541-2554

A0259 – Thermal features and behaviour of protonated diethylenetriamine isopolyvanadates

Thermal decomposition of 3-aza-l,5-pentamethylenediammonium metavanadate(V), (H2C4H13N3)(VO3)2, and bis(diethylenetriammonium) decavanadate(V) tetrahydrate, (H3C4H13N3)2[V10O28].4H2O (hereafter abbreviated as DIENVA1 and DIENVA10, respectively) has been studied by thermogravimetry (TG and DTG) and differential thermal analysis (DTA) under argon-oxygen and argon atmospheres. Thermoanalytical data show that the decomposition processes are different for both compounds and the surrounding atmosphere influences the thermal processes as well as the final products. In argon-oxygen atmosphere, the compounds undergo decomposition during several endothermic and exothermic steps to give vanadium(V) oxide. In the oxidative thermal decomposition of DIENVA10, a mixture of mixed-valance vanadium oxides, V307 and V60i3, has been identified. The experiments in an inert atmosphere lead to vanadium(IV) and vanadium(III) oxides. The essential thermal features of the protonated diethyl-enetriamine isopolyvanadates are reviewed and discussed.
P. Roman, R. Macías, A. Luque and C. Guzman-Miralles, Thermochimica Acta 209 (1992) 189-194

A0258 – Thermochemical studies of the reactions between silicon nitride and carbon

The reactions between silicon nitride and carbon were studied using thermogravimetric analysis and X-ray diffraction. A two-stage mass loss process was observed during the interaction. The first beginning at around 1130°C is related to the reaction between carbon and the surface silica of the silicon nitride powder; the second starting at about 1280° corresponds to the silicon nitride and carbon interaction. The majority of the silicon carbide was formed during the second stage without the assistance of the silica on the silicon nitride powder surfaces - a reaction mechanism for the Si3N4-C system which is different from that suggested by other researchers.
H.Y. Wang and G.S. Fischman, Thermochimica Acta 207 (1992) 201-208

A0261 – Oxidation behaviour of Si3N4-based ceramics, studied by the thermogravimetric method

The oxidation curves of three different Si3N4-based ceramics are presented. In most cases, the obtained weight gain curves do not follow the parabolic rate law (?W/Ao)2 = Kpt + B. If crystallization occurs in the formed oxide scale during the experiment, the amorphous cross section area, A, through which oxygen most easily diffuses will decrease with time. With a function A(t), which describes the time dependence of the decrease of A, incorporated into the parabolic rate law one obtains a new rate law which reads ?W/Ao = aarctan?bt +c?t. It is shown that all oxidation curves can be explained within the framework of this rate law in combination with the parabolic rate law.
J. Persson, P-O. Käll and M. Nygren, Thermochimica Acta 214 (1993) 27-31

A0260 – Preparation, chemical characterization and thermal behaviour of triethylenetetrammonium isopolyoxovanadates

The reaction of V2O5 with the triethylenetetramine base (trien) in aqueous solution, using different amounts of reactants and pH conditions, yields three new polyoxovanadates of triethylenetetrammonium: (H4trien)(VO3)4.2H2O (TRIENVA1), (H4trien)3[V10O28]2.7H2O (TRIENVA10-I), and (H4trien)[H2V10O28]-4H2O (TRIENVA10-II). The compounds were characterized by mean of chemical analysis, IR spectroscopy and thermal analysis (TG, DTA and DTG). The IR spectra indicated the presence of the triethylenetetrammonium cation and the type of polyanion in the compounds. The thermal behaviour of the compounds was studied under argon-oxygen and argon atmospheres. The final products of the thermal decompositions were analysed by elemental analysis and X-ray powder diffraction. In argon-oxygen atmosphere, all decompositions yielded vanadium(V) oxide as the final product. In argon atmosphere, the final mass losses were far higher than those expected for vanadium pentoxide, and the final products were identified as vanadium(IV) oxide for TRIENVA1 compound and a mixture of vanadium(IV) and vanadium(III) oxides for the other compounds.
P. Roman, R. Macías, A. Luque and C. Guzman-Miralles, Thermochimica Acta 209 (1992) 135-143

A0263 – New oxygen or nitrogen carriers

Complexes of nickel(II) with the composition NivOw(Imid)xAy . zNH3 or NivNw(Imid)x'Ay' . zNH3 where Imid represents the imidazole molecule and A the anion of aspartic acid, picolinic acid, glutaric and glutamic acids, N-acetylglycine or histidine, have been synthesized. The results of thermal and spectral studies are analysed for the various complexes. The TGA curves and diffuse reflectance spectra are reported. Calculated electronic transitions are in good agreement with those observed. The monomeric or dimeric character of these complexes is shown. The nickel ions seem to be in an octahedral environment.
A. Busnot, J. F. Le Querler and J. Yazbeck, Thermochimica Acta 216 (1993) 107-117

A0262 – Thermoanalytical studies on TiO2-Mica pigments

Small mica (muscovite and phologopite) flakes coated by thin TiO2 films (40-150 nm) were studied by TG, DTG and DTA methods. The films were prepared by precipitation from two different titanium chemicals, viz. TiCl4 and TiOSO4. During heating both the precipitated TiO2 hydrate films and the micas dehydrated. By thermoanalytical measurements the amount of TiO2 on the mica and the water content of the precipitate could be determined. The TG curves could also be used for identification of the titanium source chemical, precipitation process and the mica substrate used.
M. Leskelä, P. Eskelinen and M. Ritala, Thermochimica Acta 214 (1993) 19-26

A0265 – Interpretation of the parabolic and nonparabolic oxidation behavior of silicon oxynitride

The oxidation process of Si[2]N[2]O, prepared by a hot isostatic pressing technique, has been studied by the thermogravimetric method. The oxidation has been performed in oxygen for 20 h in the temperature range 1300° to 1600°C, producing oxide scales of amorphous SiO[2] and alpha-cristobalite. The weight gain for T > 1350°C does not begin to follow a parabolic rate law, until a certain time, t[0]. The A[0] parameter in the parabolic rate law, (?w/A[0])[2] = K[p]t + B, represents the cross section area, A, through which the oxygen diffuses; in the derivation of this law A is assumed to be constant during the experiment.
J. Persson, P-O. Käll, M. Nygren, Journal of the American Ceramic Society 75 (1992) 3377-3384

A0264 – Factors affecting the thermogravimetric technique in the characterization of sorbents for AFBC

Thermogravimetric analysis (TGA) is a technique usually employed for characterization of sorbents used in fluidized-bed coal combustors. Different sorbent characterization studies by TGA display great differences depending on the experimental conditions used. Mercury porosimetry and sulphation experiments made with calcined sorbents indicate that sorbent reactivity is strongly affected by the calcination conditions. In this paper, the effect of the experimental technique (sample heating rate, time before sulphation, CO2 concentration and sorbent particle size) on the sulphation is analysed. Such effects were stronger in limestones with small pores due to the sinterization effect. In addition, limestones with large pores showed the greatest capacity to react with the SO2. A set of experimental conditions for the characterization of sorbents in order to obtain reliable results is proposed.
J. Adanez and F. García-Labiano, Thermochimica Acta 217 (1993) 99-113

A0266 – Sol-gel preparation of M-Sb oxides from Sb (OBun)3-M-acetate precursors with M = Mn, Co, Ni

x
G. Westin, M. Nygren, Journal of Materials Chemistry 3 (1993) 367-371

A0267 – Application of a nonisothermal thermogravimetric method to the kinetic study of the reduction of metallic oxides, Part I : A general treatment and its application to the reduction of the oxides of molybdenum by hydrogen

Du Sichen, S. Seetharaman, Metallurgical Transactions 23B (1992) 317-324

A0270 – Synthesis of oxides, oxocarbides and carbides of molybdenum by thermal decomposition of diethylenetriamine oxomolybdenum compounds

Thermal decompositions of four diethylenetriamine oxomolybdenum compounds, the oxocomplex diethylenetriaminetrioxomolybdenum(VI), [MoO3(dien)] (DIENMO1), two polymorphs of bis(diethylenetriammonium) heptamolybdate(VI) tetrahydrate, (H3dien)2[Mo7O24].4H2O (DIENMO7-I) and (DIENMO7-II), and the bis(3-aza-l,5-penta- methylenediammonium) octamolybdate(VI) hexahydrate, (H2dien)2[Mo8O26].6H2O (DIENMO8), have been studied using TG, DTA and DTG techniques under an argon atmosphere from room temperature to 600°C. Whereas the themal decompositions of the three polyoxomolybdate salts DIEMNO7-I, DIENMO7-II, and DIENMO8 lead to a mixture of MoO2 and Mo2C, the final residue from the oxycomplex is a mixture of Mo2C and the mixed valence molybdenum(V, VI) oxide Mo4O11. The results show that the molybdenum oxide/molybdenum carbide ratio depends on the starting material. An increase in the formation of molybdenum oxide is observed as the ratio Mo/C increases. The ulterior oxidation of the final mixtures yields Mo4O11 and MoOC as intermediate solid products, and MoO3 as the final product above 535°C. The final solid residues in an argon atmosphere and the intermediate products in the oxidative atmosphere were analysed by elemental analysis and X-ray powder diffractometry.
P. Roman, A. Luque and A. Aranzabe, Thermochimica Acta 223 (1993) 167-175

A0269 – Variations de la teneur en eau des coraux lors de la transformation aragonite –> calcite

L'eau incluse est l'un des constituants des coraux fossiles. Nous avons mesuré par thermogravimétrie, la part d'eau adsorbée et surtout le pourcentage d'eau incluse qui semble constant pour les coraux qui ne contiennent que de l'aragonite (1,7%). Une diminution de la teneur en eau est observée quand le pourcentage de calcite augmente dans les échantillons. Les données sont obtenues par spectrométrie infrarouge, diffraction des rayons X et thermogravimétrie.
A. Baumer, M. Ganteaume and M. Bernat, Thermochimica Acta 221 (1993) 255-262

A0268 – Application of a nonisothermal thermogravimetric method to the kinetic study of the reduction of metallic oxides, Part II : A theoretical treatment of powder bed reduction and its application to the reduction of tungsten oxide by hydrogen

J.A. Bustnes, Du Sichen, S. Seetharaman, Metallurgical Transactions 24B (1993) 475-480

A0274 – The effect of pre-heating on the evolution of the acidity of pillared clays

Thermal studies under vacuum show that the minimum in the DTG curves ascribed to the dehydroxylation of the pillars of Al-PILC and Al-Ga-PILC samples occurs at 335 and 415°C respectively. This process produces an increase in the concentration of acid centres. This phenomenon has been related to the results obtained for pyridine desorption by IR spectroscopy. The IR spectrum of an Al-PILC sample without thermal treatment prior to pyridine sorption showed a decrease in the intensities of the typical bands of Lewis-acid centres when pyridine desorption was performed from 200 to 250°C. However, the intensities of these bands increased when pyridine desorption was performed at 300°C. In contrast, for the Al-Ga-PILC sample, there was always a decrease in the intensities of the bands. Nevertheless, when the two samples were treated at 400 or 600°C prior to pyridine sorption, they both showed a continuous decrease in the intensity of the bands of the acid centres in the pyridine desorption process over the whole temperature range tested.
C. Pesquera, F. Gonzalez, C. Blanco, I. Benito and S. Mendioroz, Thermochimica Acta 219 (1993) 179-189

A0273 – LaNi5 hydride formation. The effect of the themal conductivity of the holder on the kinetics

Samples of LaNi5H6 were synthesized in a high-pressure thermobalance; several sample containers were used, differing in shape, lateral surface and thermal conductivity. Comparative studies were made using thermal analysis. Experimental results show that a large lateral surface of the sample holder improves the heat transfer. In the case of the other holders, the temperature variations are important and experiments cannot be carried under isothermal conditions.
C. Bayane, E. Sciora, N. Gerard and M. Bouchdoug, Thermochimica Acta 224 (1993) 193-202

A0272 – Kinetic studies of LaNi5 hydride formation in non-isothermal conditions

Modelling studies are of practical importance in understanding and characterizing the kinetic behaviour of LaNi5 hydride. Theoretical predictions describing the reaction kinetics under non-isothermal conditions are in good agreement with the experimental data obtained in our experiments.
C. Bayane, E. Sciora, N. Gerard and M. Bouchdoug, Thermochimica Acta 224 (1993) 183-191

A0271 – Influence of drying on the catalytic properties of a calcium-nickel mixed orthophosphate

A. Legrouri, J. Lenzi, M. Lenzi, Journal of Thermal Analysis 39 (1993) 1321-1330

A0276 – Influence of morphology on textural properties and on the reactivity of chromium oxides obtained by decomposition of oxalate precursors (NH4)3[Cr(C2O4)3]

This article first describes a method of obtaining a chromium oxalate complex (NH4)3[Cr(C2O4)3] with extremely variable grain morphology (needles, polyhedra, platelets, spheres). The decomposition of these salts at 350°C in air leads to nonstoichiometric chromium oxides amorphous to X-rays, of composition CrOx where x is close to 1.9. p]The various oxides obtained at 350°C had very high specific surface areas of the order of several hundreds of m2g-1 which varied considerably according to the grain morphology. They all possessed a significant mesopore area with pores centred around 5 nm. p]The crystallization of CrO1.9 into alpha-Cr2O3 occurred on raising the temperature above 350°C and was accompanied by an emission of oxygen which took place in two stages. The kinetics of the oxygen emission varied with the grain morphology and could be correlated with the differences in length of the oxygen diffusion path corresponding to each oxide form.
A. Lerch and A. Rousset, Thermochimica Acta 232 (1994) 233-242

A0275 – Thermal decomposition of sodium oxalate in the presence of V2O5. Mechanistic approach of sodium oxibronzes formation

The thermal decomposition of sodium oxalate in the presence of vanadium pentoxide in 1:2 molar ratio affords the vanadium bronze alpha'-NaV2O5. Complementary techniques such as thermogravimetry (TG), differential thermal analysis (DTA), gas analysis (GC), X-ray powder diffraction (XRD) and infrared spectroscopy (IR) were applied to provide information on the operative mechanism. A promotive effect of vanadium pentoxide on the decomposition of sodium oxalate takes place. Carbonate species and carbon monoxide could not be detected as intermediates during the decomposition which occurs over a wide range of temperatures, typically between 200 and 525°C. The progressive formation of NaxV2O5 bronzes with x increasing up to unity with temperature leads us to propose that the carbon-carbon bond cleavage of the oxalate is promoted by electron transfer between the oxalate anion and the vanadium pentoxide matrix. Such behaviour is dependent on the redox potential of the metal ion initially present in the oxalate and of vanadium pentoxide.
D. Ballivet-Tkatchenko, J. Galy, J-L. Parize and J-M. Savariault, Thermochimica Acta 232 (1994) 215-223

A0278 – Ceramic membranes for industrial applications

R. de Jong, H.H. Visser, Third Euro-Ceramics 1 (1993) 663-668

A0277 – Nanostructured composite materials in the system Si-B-N

R. Schmidt, D. Sporn, U. Schubert, Third Euro-Ceramics 3 (1993) 609-615

A0280 – Preparation of lead titanate ceramics by sol-gel processing

Y.S. Kim, S. Kim, M. Yoon, Third Euro-Ceramics 2 (1993) 145-150

A0279 – Zirconia powders produced by emulsion techniques

S. Pickering, D. McGarry, D. Djuricic, Third Euro-Ceramics 1 (1993) 219-224

A0283 – Syntheses, chemical characterization, and thermochemistry of pyridinium salts of 1,2-dithiooxalato-S,S’ complexes of Ni(II), Pd(II) and Pt(II)

Three complexes of formula (HB)2[M(dto)2] where HB+ is pyridinium, M is Ni(II), Pd(II) or Pt(II), and dto2- is 1,2-dithiooxalato-S,S' (hereafter abbreviated as NIDTPY, PDDTPY and PTDTPY, respectively) have been synthesized and characterized by elemental analysis, IR and UV-vis spectroscopies and X-ray diffraction techniques. Thermal decompositions of compounds have been studied by thermogravimetry (TG and DTG) and differential thermal analysis (DTA) under argon-oxygen and argon atmospheres. The final decomposition products were identified by elemental analysis and the X-ray powder diffraction technique. Thermoanalytical data show that the surrounding atmosphere influences the course of the decomposition process, and the final products. In argon-oxygen atmosphere, the final residues were identified as a mixture of nickel sulphides, oxides and sulphate for the nickel compound, Pd(0) and PdO for the palladium compound, and platinum(0) for the platinum compound. Thermal decompositions in argon atmosphere yielded nickel(II) sulphide, a mixture of Pd/PdS, and metallic platinum, respectively.
P. Roman, J.I. Beitia and A. Luque, Thermochimica Acta 241 (1994) 113-120

A0281 – Strengthening of mica glass ceramics

M. Reise, G. Müller, Third Euro-Ceramics 2 (1993) 1151-1156

A0286 – Décomposition thermique d’hydroxyapatites carbonatées sodées

Une série d'hydroxyapatites carbonatées sodées (HApCO3Na) de composition variable a été synthétisée par la méthode de précipitation. Le dosage chimique, la spectroscopie IR et la diffraction des rayons X ont permis de distinguer les HApCO3Na faiblement carbonatées des HApCO3Na à teneur élevée en carbonate. L'étude de la décomposition thermique de ces phosphates réalisée par thermogravimétrie (ATG) couplée à l'analyse des gaz émis (AGE), montre qu'au delà de la déshydratation, la décarbonatation se fait en deux étapes. Compte tenu, des résultats obtenus (IR, AGE) pour ces apatites, nous avons pu attribuer la premiere décarbonatation à la décomposition des ions carbonate de type B. Quant à la seconde décarbonatation elle serait engendrée par la décomposition des ions carbonates de type B et A. La présence de ces derniers serait le résultat d'une restructuration du réseau.
H. El Feki, I. Khattech, M. Jemal and C. Rey, Thermochimica Acta 237 (1994) 99-110

A0285 – Etude ATD-ATG du polyéthylène ignifugé par l’hydroxyde de magnésium

Fire resistance of polyethylene is realized by magnesium hydroxide which is distinguished from halogenated fire-proofing agents by its lower cost and its non toxicity. Magnesium hydroxide decomposed by an endotbermic reaction with liberation of water, contributing to ttre proofing. The sample used (Kisuma 5A-N*) is constituted from a powder (0.6-0.8 micrometre) its surface is treated by plastic material in order to ameliorate its compatibility. We studied the thermal decomposition by DTA and TG, of mixtures constituted by polyethylene and magnesium hydroxide. A sudden decomposition began at 385°C for pure polyethylene and decomposition took place at 429°C for the mixture polyethylene-Kisuma (50-50). Incorporation of magnesium hydroxide in polyethylene increases fire resistance.
E. Renacco, J. Kaloustian, C. Arfi, A.M. Pauli and J. Pastor, Journal of Thermal Analysis 41 (1994) 881-888

A0284 – Kinetic studies of the reactions between silicon nitride and carbon

The reactions between silicon nitride and carbon take place in two stages, the surface silica of silicon nitride powders reacts with carbon first followed by the decomposition of silicon nitride and the residual silicon reacting with carbon. The kinetics of the two stage reactions has been studied by isothermal thermogravimetric analysis. Physico-geometric models for both of the reaction stages have been proposed, and the kinetic parameters have been calculated. The implications of the kinetic models and parameters are discussed.
H. Wang, G.S. Fischman, Journal of Thermal Analysis 41 (1994) 135-146

A0288 – Thermal features and behaviour of 4-aminopyridinium salts of planar inorganic metal(II) 1,2-dithiooxalato-S,S’ complexes, with formula (HC5H6N2)2[M(S2C2O2)2].2H2O (where M is Ni(II), Pd(II) and Pt(II)

Thermal decompositions of three 4-aminopyridinium salts of square-planar inorganic metal(II) 1,2-dithiooxalato-S,S' complexes, (HC5H6N2)2[M(S2C2O2)2] . 2H2O where M is Ni(II), Pd(II) and Pt(II) (hereafter abbreviated as NIDT4AP, PDDT4AP and PTDT4AP, respectively) have been studied by thermogravimetry (TG and DTG) and differential thermal analysis (DTA) under argon-oxygen and argon atmospheres. Thermoanalytical data show that the surrounding atmosphere influences the thermal decomposition processes as well as the final products. In argon-oxygen atmosphere, the final residues were identified as a mixture of nickel sulphides and oxides for NIDT4AP, metallic palladium and palladium oxide for PDDT4AP, and platinum(0) for PTDT4AP. Thermal decompositions in an inert atmosphere yielded nickel(II) sulphide for NIDT4AP, a mixture of Pd/PdS for PDDT4AP, and metallic platinum for PTDT4AP. The final decomposition products were identified by elemental analysis and the X-ray powder diffraction technique. No other stable intermediate products, except the corresponding anhydrous compounds, were found during the thermal decomposition owing to the complexity and the overlap of the processes in oxidative and inert atmospheres.
P.Roman, A. Luque, J.I. Beitia and C. Guzman-Miralles, Thermochimica Acta 231 (1994) 231-237

A0287 – Transformations de la phase supraconductrice à haute Tc (Bi,Pb)2Sr2CaCu2O8+x

DTA-DTG systematic study of high Tc superconducting phase (Bi,Pb)2Sr2CaCu2O(8+x), with and without lead, shows a quantitatively opposite variation of oxygen stoechiometry on heating and cooling. Multiplate sample container, designed for the study, allowed to dissociate PbO loss from oxygen variations. Phases transformations have been studied under several P(O2) by scanning DTA and DTG. Oxygen variations evolution has been evaluated by isothermal TG. The results proved that phase diagram representation must take into consideration the P(O2) coordinate.
P. Satre, A. Sebaoun, Journal of Thermal Analysis 41 (1994) 211-224

A0290 – Synthesis of the first example of a dinuclear syn-anti carboxylate-bridged copper(II) complex from a related hydrogen-bonded dinuclear copper(II) complex by thermal treatment

The synthesis of the first example of a dinuclear syn-anti carboxylate-bridged copper(II) complex from a related hydrogen-bonded dinuclear copper(II) complex with the ligand 1,3-dimethyl-5-[(2-carboxyphenyl)azo]barbituric acid by thermal treatment is discussed. This method is particularly useful because direct synthesis of the dinuclear syn-anti carboxylate-bridged copper(II) complex is difficult. Both complexes have been studied by thermogravimetric and differential scanning calorimetric techniques, and from spectroscopic and X-ray diffraction measurements.
J.M. Moreno, R. Cuesta, J.M. Dominguez-Vera and D. Galisteo, Thermochimica Acta 233 (1994) 329-335

A0289 – Thermal properties of sodium-light-lanthanoid double sulfate monohydrates

The thermal decomposition of sodium-light-lanthanoid double sulfate monohydrates up to 1600°C has been studied by TG, DTG, DTA, IR and X-ray diffraction methods. The information obtained by IR and X-ray techniques verified the crystal structure of the NaLn(SO4)2 . H2O-type compounds. TG analyses revealed that after dehydration the decomposition reaction proceeds with the formation of NaLnOSO4, then Ln2OSO4, with the removal of Na2O, followed by Ln2O2SO4 and finally the oxide of the lanthanide is formed. It was found that the cerium double sulfate decomposes anomalously. In the dehydration stage, all the compounds exhibited a behavior that was different from that of the hydrated rare-earth sulfates.
Ö. Kolcu and B. Zümreoglu-Karan, Thermochimica Acta 240 (1994) 185-198

A0291 – Synthesis, chemical characterization and thermal behaviour of 1,2-dithiooxalato-S,S’ complexes of Ni(II), Pd(II) and Pt(II) with 2-amino-3-methylpyridinium

Three compounds of formula (HB)2[M(dto)2], where HB+ is 2-amino-3-methylpyridinium, dto2- is 1,2-dithiooxalato-S,S' ligand, and M is Ni(II), Pd(II), or Pt(II), have been synthesized and characterized by elemental analysis, and infrared and UV-Vis spectroscopy. The thermal behaviour of these complexes was studied by thermogravimetry (TG) and differential thermal analysis (DTA) under argon and argon-oxygen atmospheres. The final products of the thermal decomposition were examined by elemental analysis and X-ray powder diffractometry. The IR and UV-Vis spectra indicate the presence of the aromatic cations and the complex anions. The thermal analytical data show that the starting compounds and the surrounding atmosphere significantly influence the course of the decomposition reactions, as well as the final products. In an oxidative atmosphere, a mixture of nickel(II, III) oxides and sulphides, palladium(II) oxide and metallic platinum were obtained, whereas in an inert atmosphere, nickel sulphides, palladium(II) sulphide and platinum(0) were identified as the final products.
P. Roman, J.I. Beitia and A. Luque, Thermochimica Acta 233 (1994) 223-230

A0295 – Analysis of the direct sulfation of calcium carbonate

The kinetics of the direct CaCO3particles is investigated. The experiments were carried out in a thermogravimetric analyzer under isothermal conditions between 740 and 890°C. A pure calcium carbonate sample with a mean size of 16 ?m and a specific surface area of 0.6 m2 g-1 was used. The variation of reaction rate with temperature shows that the process is controlled by the chemical reaction. An activation energy of around 110-130 kJ mol-1 was measured. The dependence between chemical rate and temperature is given by kp = 740 exp(-113000/ RT) (mol m-2) s atm. The process was modeled according to a shrinking unreacted core model. Whereas the CaO sulfation stops due to the blockage of external pores, the CaCO3 sulfation does not exhibit abrupt changes in reactivity, probably due to the porosity of the production layer. The recarbonated samples show higher sulfation rates than uncalcinated CaCO3 samples.
A.B. Fuertes, G. Velasco, M.J. Fernandez and T. Alvarez, Thermochimica Acta 242 (1994) 161-172

A0294 – Synthetic resins as carbon forming agents for various refractories (carbon yields, analytical methods, structures and emissions)

A. Gardziella, R. Solozabal, J. Suren, V. in der Wiesche

A0293 – Charakterisierung von organokieselsäurepolymeren durch thermoanalytische untersuchungen

Four organosilicate polymers synthesized by addition of vinyl- and H-substituted double four-ring silicic acid derivatives were characterized using DSC and simultaneous TG-DTA measurements. Thermooxidative decomposition proceeds in several steps: Oxidation of (Si-H) groups, oxidation of (Si-CH2-CH2-Si) bridges, and oxidation of (Si-CH3) groups, with formation of new (Si-O-Si) bonds. 29Si-NMR-spectroscopic measurements confirm this interpretation. Thermoanalytical methods of investigation proved useful to characterize these organosilicate polymers.
P. Kölsch, I. Pitsch, D. Schultze, D. Heidemann, D. Hoebbel, Journal of Thermal Analysis 41 (1994) 789-806