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Abstract  

The synthesis of hydroxylammonium uranyl acetate is described. The identity of the synthesized compound was confirmed by chemical and infrared analysis. The intermediates and final products of the thermal decomposition were identified by means of thermogravimetric analysis, differential thermal analysis and X-ray diffraction. The thermal decomposition of hydroxylammonium uranyl acetate involves several steps. Two of them are due to decomposition of this compound to UO2 via UO2(CH3COO)2, and the third to the partial oxidation of UO2 to UO3 and the formation of U2O8 in the solid state at higher temperature.

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Abstract  

The present paper deals with thermal decomposition of some spatially hindered phenols, which are in the industry as stabilizers in synthetic materials used. The investigated stabilizers are separated to two groups in respect to mechanism of decomposition (group I and II). This assumption was confirmed by chromatomass-spectrometric investigations. It allows a stabilizer for forming a plastic with variety properties to choose.

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The thermal decomposition of the only known antimony nitrate antimony(III) oxide hydroxide nitrate Sb4O4(OH)2(NO3)2, whose synthesis routes were reviewed and optimized was followed by TG-DTA under an argon flow, from room temperature up to 750°C. Chemical analysis (for hydrogen and nitrogen) performed on samples treated at different temperatures showed that an amorphous oxide hydroxide nitrate appeared first at 175°C, and decomposed into an amorphous oxide nitrate above 500°C. Above 700°C, Sb6O13 and traces of α-Sb2O4 crystallized.

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Thermal decomposition of nickel(II) complexes under quasi-equilibrium conditions

IV. Stoichiometry of thermal decomposition, thermal stability and stereochemistry of complexes

Journal of Thermal Analysis and Calorimetry
Authors:
E. Jóna
,
A. Mašlejová
,
M. Kubranová
, and
P. Šimon

The stoichiometry of thermal decomposition and the relationship between the thermal parameters (quasi-equilibrium decomposition temperaturesT D and decomposition entalpies ΔH D) of NiL4(NCS)2 complexes (L=imidazole derivatives) were studied. It was found that changes in the experimental conditions strongly influence the decomposition stoichiometry. TheT D and ΔH D can be ordered in the following sequence (according toL): imidazole<2-Me imidazole<2-Et imidazole<l-Me imidazole.

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Abstract  

The kinetics of manganese(II) oxalate thermal decomposition in the helium atmosphere was studied on the basis of isothermal measurements in the temperature range from 608 to 623 K. Manganese(II) oxide, MnO, was found to be the final product of reaction. The Avrami-Erofeev kinetic equation was used to describe all the experimental data in the range of decomposition degrees from 0.1 to 0.9. The determined activation energy equals 184.7 kJ mol-1 with standard deviation 5.2 kJ mol-1. The estimated value of parameter n is 1.9 with standard deviation 0.01 what suggests that the rate limiting step of MnC2O4 decomposition is the nucleation of new MnO phase and that the rate of nuclei growth is rising during decomposition.

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Abstract  

Thermal decomposition of several purine derivatives used in medicine –theophylline, theobromine, caffeine, diprophylline and aminophylline was investigated. The analyses were performed using a derivatograph. It has been established, that the thermal decomposition of purine derivatives occurs via three stages. The stages of dehydratation of hydrate and evaporation of aminophylline are distinctly marked on the thermoanalytical curves, which may be used for the control of composition of the studied compounds. The ranges of temperature, in which the analyzed compounds can be technologically transformed without change of their physicochemical properties, were also established. Moreover, the influence of heating rate and sample size on the thermal decomposition of the examined compounds was evaluated.

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Journal of Thermal Analysis and Calorimetry
Authors:
Igor Dalinger
,
Svyatoslav Shevelev
,
Vyacheslav Korolev
,
Dmitriy Khakimov
,
Tatyana Pivina
,
Alla Pivkina
,
Olga Ordzhonikidze
, and
Yuriy Frolov

intramolecular interactions should be responsible for the thermal stability and mechanisms of thermo decomposition of highly nitrated azoles. Kinetics of thermolysis provides a good approach for the mechanism of thermal decomposition of new compounds. We report

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Abstract  

The results of first principles calculations of band structure, density of states and electron density topology of ZnC2O4 crystal are presented. The calculations have been performed with WIEN2k FP LAPW ab initio package. The obtained SCF electron density has been used in calculations of Bader’s QTAIM (quantum theory of atoms in molecules) topological properties of the electron density in crystal. Additional calculations of bond orders (Pauling, Bader, Cioslowski and Mixon) and bond valences according to bond valence model have been done. The obtained results are analyzed from the point of view of the thermal decomposition process, and this analysis indicates, that most probably this compound should decompose to metal oxide, carbon oxide and carbon dioxide, in agreement with the experiment.

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Journal of Thermal Analysis and Calorimetry
Authors:
Anna Migdał-Mikuli
,
Elżbieta Szostak
,
K. Drużbicki
, and
Diana Dołȩga

Abstract  

Tetrakis(dimethyl sulphoxide)nickel(II) bis(iodide) was studied by thermogravimetry (TG) and simultaneous differential thermal analysis (SDTA) and differential scanning calorimetry (DSC). The gaseous products of the decomposition were on-line identified by a quadrupole mass spectrometer (QMS). Thermal decomposition of the title compound proceeds in three main stages. In the first stage, which starts just above ca. 419 K, the compound loses two dimethyl sulphoxide (DMSO) molecules per one formula unit and small amount of iodide ion. In the second stage (464–552 K) the next DMSO ligands and the iodide ion simultaneously are released. In the last stage (552–900 K) NiSO4 is created which next decomposes to NiO and SO3.

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Abstract  

Lanthanide picrates with 1,3-dithiane-1,3-dioxide ligand were synthesized and characterized. Thermal decomposition of these compounds by TG/DTG and DSC and structural studies were performed. It was found that the compounds are comprised in a single isomorphous series and their thermal decomposition occurs as exothermic events. The final products were found to be lanthanide dioxysulfates.

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