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.
Authors:M. Ştefănescu, O. Ştefănescu, M. Stoia, and C. Lazau
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.
formation of the metal-organic precursors and their thermal decomposition
were studied by thermal analysis and FTIR spectroscopy.
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).
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.
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.
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.
Authors:Y. Pelovski, M. Tsankov, V. Petkova, and I. Gruncharov
Dynamic TG investigations were carried out to elucidate the mechanism of thermal decomposition of aluminium sodium sulphate
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.
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.
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.
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.
Authors:Sulene Araújo, Antonio Araujo, Nedja Fernandes, Valter Fernandes, and Massao Ionashiro
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 thermaldecomposition