The application of DTA to fluxed melts is discussed, and an apparatus for the determination of the solubility of crystalline materials in molten solutions is described. An exploratory study of the crystallization of nickel ferrite from barium borate fluxes is also described, and solubility curves are presented for fluxes which favour crystal growth. The heat of solution of nickel ferrite was found to be 73 ± 2 Kjoule mole−1.
Conditions are presented for application of the Piloyan method to the DTA of poly-nitro aromatic compounds. Activation energies (E) of the thermal decomposition and the initial valuesTD of the exotherms are determined for trinitrotoluene, trinitro-m-xylene, trinitromesitylene, picryl chloride and dichlorotrinitrobenzene. Linear relationships are derived between the termsE · T
The Piloyan activation energiesE of decomposition and the initial temperaturesTD of the exotherms of hexanitrobiphenyl (HNB), nonanitro-m-terphenyl (NONA), tripicryl-s-triazine (TPT) and 1,4,5,8-tetranitronaphthalene (TENN) have been determined by means of non-isothermal DTA. Due to its volatility in the zone of the beginning of thermal decomposition onlyTD values are specified fors-trinitrobenzene (TNB). From the values ofE ·TD−1 for HNB and from the derived values ofE ·TD−1 for TNB on the one hand, and from the published values of the Arrhenius parameters obtained by means of the manometric method on the other, relationships have been derived. The relationship betweenE ·TD−1and the standard activation enthropy is considered relevant.
Authors:Yu. Goltsov, L. Matkovskaya, V. Il'in, and V. Golovaty
The results of investigation of the influence of encapsulation on the mechanism of thermal decomposition of cyanide transition
metal complexes, based on data obtained by methods of differential thermal analysis (inert atmosphere) and thermodesorption
(mass-spectral monitoring of gaseous products) are represented. It was established, that encapsulation of cyanide iron(II)
and cobalt(III) complexes in faujasite type zeolite results in the hydrolytic mechanism of thermal destruction of complexes,
unlike to bulk analogues, which is determined by essential decreasing of the temperature of complex anions encapsulated destruction
beginning, up to temperatures while zeolite water molecules are saved; the gaseous products of thermal destruction composition
is determined by the peculiarities of localization of cations of different nature in inclusion compounds.
Authors:S. Marinković, A. Kostić-Pulek, S. Durić, V. Logar, and M. Logar
Selenite was boiled in KCl solutions of different concentrations at the respective boiling temperatures and atmospheric pressure. The products were subjected to X-ray diffraction analysis, qualitative infrared analysis, differential thermal analysis and microscopic examination. The product obtained in 1.0 M KCl solution was the -form of calcium sulphate hemihydrate (-CaSO4·0.5H2O). In more concentrated KCl solution (1.5, 2.0, 2.5, 3.0, 3.5 or 4.0 M), the -form of calcium sulphate hemihydrate (-CaSO4·0.5H2O) was formed, and a reaction took place between KCl and CaSO4, which gave a double salt: potassium pentacalcium sulphate monohydrate (K2SO4·5CaSO4·H2O).
Authors:P. Pasierb, R. Gajerski, S. Komornicki, and M. Rękas
The binary system Li2CO3–BaCO3 was studied by means of differential thermal analysis (DTA), thermogravimetry (TG) and X-ray phase analysis. The composition
of carbonate and CO2 partial pressure influence on the thermal behavior of carbonate were examined. It was shown that lithium carbonate does not
form the substitutional solid solution with barium carbonate, however the possible formation of diluted interstitial solid
solutions is discussed. Above the melting temperature the mass loss is observed on TG curves. This loss is the result of both
decomposition of lithium carbonate and evaporation of lithium in Li2CO3–BaCO3 system. Increase of CO2 concentration in surrounding gas atmosphere leads to slower decomposition of lithium carbonate and to increase the melting