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Abstract  

The mineral stichtite was synthesised and its thermal decomposition measured using thermogravimetry coupled to an evolved gas mass spectrometer. Mass loss steps were observed at 52, 294, 550 and 670�C attributed to dehydration, dehydroxylation and loss of carbonate. The loss of carbonate occurred at higher temperatures than dehydroxylation.

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Abstract  

Thermal decomposition of borax has been researched by thermal, XRD and FTIR methods as well as SEM microscopy. Study have revealed that it proceeds according to the mechanism of internal reactions in the structure of the precursor as a medium. The following stages of the process have been distinguished: (1) dehydration, (2) internal structure reconstitution—formation of tincalconite, (3) amorphization of crystal structure, (4) gradual dehydroxylation and crystallization of Na2O2B2O3 inside the amorphous matrix.

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Thermal decomposition of sabugalite

A controlled rate thermal analysis study

Journal of Thermal Analysis and Calorimetry
Authors: R. Frost, J. Kristóf, W. Martens, M. Weier, and E. Horváth

The mineral sabugalite (HAl)0.5[(UO2)2(PO4)]2⋅8H2O, has been studied using a combination of energy dispersive X-ray analysis, X-ray diffraction, dynamic and controlled rate thermal analysis techniques. X-ray diffraction shows that the starting material in the thermal decomposition is sabugalite and the product of the thermal treatment is a mixture of aluminium and uranyl phosphates. Four mass loss steps are observed for the dehydration of sabugalite at 48°C (temperature range 39 to 59°C), 84°C (temperature range 59 to 109°C), 127°C (temperature range 109 to 165°C) and around 270°C (temperature range 175 to 525°C) with mass losses of 2.8, 6.5, 2.3 and 4.4%, respectively, making a total mass loss of water of 16.0%. In the CRTA experiment mass loss stages were found at 60, 97, 140 and 270°C which correspond to four dehydration steps involving the loss of 2, 6, 6 and 2 moles of water. These mass losses result in the formation of four phases namely meta(I)sabugalite, meta(II)sabugalite, meta(III)sabugalite and finally uranyl phosphate and alumina phosphates. The use of a combination of dynamic and controlled rate thermal analysis techniques enabled a definitive study of the thermal decomposition of sabugalite. While the temperature ranges and the mass losses vary due to the different experimental conditions, the results of the CRTA analysis should be considered as standard data due to the quasi-equilibrium nature of the thermal decomposition process.

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containing crystalline water are heated, one endothermic effect (always below 200 °C) corresponds to a release of the water molecules. Afterward, the thermal decomposition occurs at higher temperatures depending on the composition of the starting compound

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Abstract  

In order to investigate the formation of the multiferroic BiFeO3, the thermal decomposition of the inorganic complex Bismuth hexacyanoferrate (III) tetrahydrate, Bi[Fe(CN)6]·4H2O has been studied. The starting material and the decomposition products were characterized by IR spectroscopy, thermal analysis, laboratory powder X-ray diffraction, and microscopic electron scanning. The crystal structures of these compounds were refined by Rietveld analysis. BiFeO3 were synthesized by the decomposition thermal method at temperature as low as 600 °C. There is a clear dependence of the type and amount of impurities that are present in the samples with the time and temperature of preparation.

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Thermal decomposition of methylxanthines

Interpretation of the results by PCA

Journal of Thermal Analysis and Calorimetry
Authors: M. Wesolowski and P. Szynkaruk

Abstract  

The thermal decomposition of theophylline, theobromine, caffeine, diprophylline and aminophylline were evaluated by calorimetrical, thermoanalytical and computational methods. Calorimetrical studies have been performed with aid of a heat flux Mettler Toledo DSC system. 10 mg samples were encapsulated in a 40 μL flat-bottomed aluminium pans. Measurements in the temperature range form 20 to 400°C were carried out at a heating rate of 10 and 20°C min−1 under an air stream. It has been established that the values of melting points, heat of transitions and enthalpy for methylxanthines under study varied with the increasing of heating rate. Thermoanalytical studies have been followed by using of a derivatograph. 50, 100 and 200 mg samples of the studied compounds were heated in a static air atmosphere at a heating rate of 3, 5, 10 and 15°C min−1 up to the final temperature of 800°C. By DTA, TG and DTG methods the influence of heating rate and sample size on thermal destruction of the studied methylxanthines has been determined. For chemometric evaluation of thermoanalytical results the principal component analysis (PCA) was applied. This method revealed that first of all the heating rate influences on the results of thermal decomposition. The most advantageous results can be obtained taking into account sample masses and heating rates located in the central part of the two-dimensional PCA graph. As a result, similar data could be obtained for 100 mg samples heated at 10°C·min−1 and for 200 mg samples heated at 5°C min−1.

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Journal of Thermal Analysis and Calorimetry
Authors: E. M. Schwartz, I. M. Vitola, G. S. Sergeiyeva, G. O. Piloyan, and O. V. Drozdova

The thermal decompositions of dicitratoborates M1[B(C6H6O7)2]·nH2O (n=0–2, M1=Rb, K, Li, NH4) and M11[B(C6H6O7)2]2·8H2O (M11=Co, Ni, Mn, Cu, Zn, Cd) were investigated by means of TG, DTA and DTG methods. It was found that these thermal decompositions involve three successive stages: dehydration, the endothermal decomposition of the ligand, and oxidation of the residual organic component. The volatile products of decomposition in each stage were detected by means of gas chromatography. The method of TG-curve transformation into the curvedm/d T vs.m, wherem is the loss of weight at each moment of time, was used for a more detailed study of dehydration. The optimal conditions for TG-curve modification were found.

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Journal of Thermal Analysis and Calorimetry
Authors: Annamária Krajníková, Katarína Győryová, Daniela Hudecová, Jana Kovářová, and Zuzana Vargová

works we described the preparation, thermal, spectral and biological properties of aliphatic zinc(II) carboxylates [ 13 – 15 ], salicylates and halogenosalicylates [ 16 , 17 ] and benzoates [ 18 , 19 ]. It was found that the thermal decomposition of

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Journal of Thermal Analysis and Calorimetry
Authors: V. M. Abdul Mujeeb, K. Muraleedharan, M. P. Kannan, and T. Ganga Devi

analysis (TG) is usually adopted to study the kinetics of thermally activated solid-state reactions to obtain thermal stability parameters of solids [ 9 – 13 ]. The kinetics of the thermal decomposition of inorganic materials could be markedly affected by

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Journal of Thermal Analysis and Calorimetry
Authors: Luiz Carlos Machado, Marcos Tadeu D’Orlando de Azeredo, Hamilton Perez Soares Corrêa, Jivaldo do Rosário Matos, and Ítalo Odone Mazali

) (where Ln = La, Pr, Nd, Sm, Eu, and Gd) have been produced from the thermal decomposition of hydrated lanthanide sulfates at temperatures >1073 K for 5 h under N 2 or air [ 1 , 8 ]. Subsequent reduction of as prepared Ln 2 O 2 SO 4 under a H 2 flow (3

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