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Abstract  

Barium benzoate was synthesized in a hydrothermal reaction. The complex was characterized by elemental analysis, IR spectroscopy and X-ray powder diffraction. It was monoclinic and had a layered structure. The mechanism of thermal decomposition of the barium benzoate was studied by using TG, DTA, IR and gas chromatography-mass spectrometry. In a nitrogen atmosphere, the barium benzoate decomposed to form BaCO3 and organic compounds: mainly benzophenone, triphenylmethane, etc.

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Journal of Thermal Analysis and Calorimetry
Authors: M. Ştefănescu, O. Ştefănescu, M. Stoia, and C. Lazau

Abstract  

In this paper we present a study on the synthesis of Fe(III) oxide, by thermal decomposition of some complex combinations of Fe(III) with carboxylate type ligands, obtained in the redox reaction between some polyols (ethylene glycol (EG), 1,2-propane diol (1,2PG), 1,3-propane diol (1,3PG) and glycerol (GL)) and NO3 ions (from ferric nitrate). Fe2O3 was obtained by thermal decomposition of the synthesized metal-organic precursors at low temperatures. γ-Fe2O3 was obtained as nanoparticles at 300C, while at higher temperatures α-Fe2O3 starts to crystallize and becomes single phase at ~500C. The formation of the metal-organic precursors and their thermal decomposition were studied by thermal analysis and FTIR spectroscopy. The evolution of Fe2O3 crystalline phases with the thermal treatment of iron complexes was followed by RX diffractometry. The size of γ-Fe2O3 nanoparticles was estimated by transmission electron microscopy (TEM).

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Abstract  

The thermal decomposition of -irradiated cadmium bromate was studied by dynamic thermogravimetry. The reaction order, activation energy, frequency factor and entropy of activation were computed using the Coats-Redfern method and were compared with those of the unirradiated salt. Irradiation enhances the decomposition and the effect increases with irradiation dose. The activation energy decreases on irradiation. The mechanism for the decomposition of unirradiated and irradiated cadmium bromate follows the Avrami model equation, 1-/1-/1/3=kt, and the ratecontrolling process is a phase-boundary reaction assuming spherical symmetry.

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Abstract  

Mono- and binuclear rubidium-sodium halidothiocyanatobismuthates(III) have been prepared. Thermal, chemical and X-ray analyses were used to establish the thermal decomposition course of these complexes. The pyrolysis occurs in three stages connected with the mass loss and exothermic effects. The decomposition temperatures of the title salts are 190–210°C.

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The conditions of thermal decomposition of Tb(III), Dy, Ho, Er, Tm, Yb and Lu aconitates have been studied. On heating, the aconitates of heavy lanthanides lose crystallization water to yield anhydrous salts, which are then transformed into oxides. The aconitate of Tb(III) decomposes in two stages. First, the complex undergoes dehydration to form the anhydrous salt, which next decomposes directly to Tb4O7. The aconitates of Dy, Ho, Er, Tm, Yb and Lu decompose in three stages. On heating, the hydrated complexes lose crystallization water, yielding the anhydrous complexes; these subsequently decompose to Ln2O3 with intermediate formation of Ln2O2CO3.

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Abstract  

Dynamic TG investigations were carried out to elucidate the mechanism of thermal decomposition of aluminium sodium sulphate crystallohydrate. Shimadzu 31H and MOM Derivatograph X-ray diffraction and other techniques were used to determine data on the decomposition, activation energy, structure and phases in the solid products. Isothermal study in the temperature ranges 883–958 K and 983–1113 K in air or a reducing gas atmosphere revealed different reaction mechanisms. Depending on the experimental conditions, mainly Al2O3 can be obtained.

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Abstract  

The thermal decompositions of a double-base propellant (DB), five triple-base propellants (TB) and nitroguanidine (NGV) were examined. The kinetic parameters were evaluated using the ASTM, Kissinger, Rogers-Morris, Freeman-Carroll and Borchardt-Daniels methods. The values of the orders of some of the chemical reactions (n), like some values of activation energies (Ea), do not have any physical meaning, but they represent the manner of propellant decomposition and prove that the mechanism of the reaction changes during the decomposition process. As a result of this fact, differences appear in the evaluated kinetic parameters between various methods.

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Abstract  

There is a thin layer of organic lubricant on commercial silver flake surfaces. This lubricant layer is a fatty acid salt formed between a fatty acid and silver flake surfaces. Thermal decomposition behavior of the silver flake lubricant is investigated in this study. The heat flow and mass loss of a silver flake are studied using differential scanning calorimetry (DSC) and thermogravimetry (TG), respectively. The silver flake is also oven heated to different isothermal temperatures (150,190, 250 and 300C) for one h. Then chemical nature of the lubricant of the heated silver flake sample are studied using diffuse reflectance infrared Fourier transfer spectroscopy (DRIFTS). Based on the results, a mechanism of thermal decomposition of the silver flake lubricant is proposed. It is found that decomposition of the lubricant - the fatty acid salt -includes the release of the fatty acid, formation of short chain acids by decomposition of hydrocarbon moiety of the fatty acid, and formation of alcohols through decarbonation of the short chain acids.

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The thermal decomposition of lead thiosulfate (LTS) was studied by various methods: X-ray phase analysis, IR and ESR spectroscopy, etc. A mechanism of thermal decomposition is suggested, including rupture of the S-S bond and the formation of radicals. According to the mechanism, the reaction rate can be enhanced in the presence of the PbS phase. The formation of PbS is the cause of the topochemical character of the reaction. The composition of the thermolysis products of LTS containing a radioactive isotope of sulfur is predicted.

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summary, this method for determining the activation from thermogravimetric plots involves only the reading of the temperature at a constant weight loss from TG curves at different heating rates [ 15 ]. The kinetic study of the thermal decomposition

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