Authors:K. P. Sharma, R. S. B. Reddi, and R. N. Rai
discussion. However, the monotectic alloys have been studied very less due to several difficulties associated with the miscibility gap systems. In this communication, the phase diagram, solidification behavior, thermochemistry, and microstructures of 1
Authors:S. Chen, X. Meng, Q. Shuai, B. Jiao, S. Gao, and Q. Shi
solid complex Eu(C5H8NS2)3(C12H8N2) has been obtained from reaction of
hydrous europium chloride with ammonium pyrrolidinedithiocarbamate (APDC)
and 1,10-phenanthroline (o-phen⋅H2O)
in absolute ethanol. IR spectrum of the complex indicated that Eu3+
in the complex coordinated with sulfur atoms from the APDC and nitrogen atoms
from the o-phen. TG-DTG investigation provided
the evidence that the title complex was decomposed into EuS.
enthalpy change of the reaction of formation of the complex in ethanol, ΔrHmθ(l), as –22.2140.081 kJ mol–1,
and the molar heat capacity of the complex, cm,
as 61.6760.651 J mol–1 K–1,
at 298.15 K were determined by an RD-496 III type microcalorimeter. The enthalpy
change of the reaction of formation of the complex in solid, ΔrHmθ(s), was calculated as 54.5270.314 kJ mol–1
through a thermochemistry cycle. Based on the thermodynamics and kinetics
on the reaction of formation of the complex in ethanol at different temperatures,
fundamental parameters, including the activation enthalpy (ΔH≠θ),
the activation entropy (ΔS≠θ),
the activation free energy (ΔG≠θ),
the apparent reaction rate constant (k),
the apparent activation energy (E), the
pre-exponential constant (A) and the reaction
order (n), were obtained. The constant-volume
combustion energy of the complex, ΔcU,
was determined as –16937.889.79 kJ mol–1
by an RBC-II type rotating-bomb calorimeter at 298.15 K. Its standard enthalpy
of combustion, ΔcHmθ,
and standard enthalpy of formation, ΔfHmθ,
were calculated to be –16953.379.79 and –1708.2310.69
kJ mol–1, respectively.
Authors:V. Ovchinnikov, T. Makeeva, L. Lapteva, V. Valiullina, L. Pilishkina, and A. Konovalov
The enthalpies of vaporization of different classes three-coordinated arsenic compounds have been determined according to
their enthalpies of solution in hexane and molar refraction. The enthalpies of solvation of cyclic and acyclic As(III)-derivatives
in hexane, carbon tetrachloride,p-xylene and pyridine are obtained and discussed.
, respectively, were derived from the standard molar energies of combustion, in oxygen, to yield CO2(g) and H2O(l), at T = 298.15 K, measured by static bomb combustion calorimetry. The Knudsen mass-loss effusion technique was used to measure
the dependence of the vapour pressure of the solid isomers of hydroxymethylphenol with the temperature, from which the standard
molar enthalpies of sublimation were derived using the Clausius–Clapeyron equation. The results were as follows:
, for 2-, 3- and 4-hydroxymethylphenol, respectively. From these values, the standard molar enthalpies of formation of the
title compounds in their gaseous phases, at T = 298.15 K, were derived and interpreted in terms of molecular structure. Moreover, using estimated values for the heat capacity
differences between the gas and the crystal phases, the standard (p° = 0.1 MPa) molar enthalpies, entropies and Gibbs energies of sublimation, at T = 298.15 K, were derived for the three hydroxymethylphenols.
Authors:P. Melnikov, M. Secco, W. Guimarães, and H. dos Santos
A vitreous form of antimony orthophosphate has been obtained using antimony polyphosphate as a precursor. Morphologically,
it is composed of small uniform grains having ellipsoidal shapes. Prolonged thermal treatment leads to the transformation
into a crystalline variety. According to TG curves, both forms start to evaporate at 920°C without decomposition. Melting
point of crystalline SbPO4 has been determined to be 877°C. Thermomechanical study reveals plastic behavior due to the capacity to flow under shearing
stress. Ceramics formation in the system Sb2O3-SbPO4 is discussed. The presence of glass domains in this system has not been confirmed.
Mutual relation between thermal activity and biochemical activity of the phospho-silicate glasses which are used as controlled
rate release fertilisers and bioglasses for medical applications, has been observed. Analysis of the local atomic interactions
in the structure of glass is used to explain this relation.
Authors:Yu. Sazanov, M. Goykhman, I. Podeshvo, G. Fedorova, G. Mikhailov, and V. Kudriavtsev
Thermal analysis of polyester and polyamides based on vanillic acid derivative — terephthaloyl-bis-(3-methoxy-4-oxy benzoic)
acid has been reported. Different behaviours with the appearance of the thermal degradation, stucturization and carbonization
stages were detected.
Thermochemical behaviour of polymers under investigation revealed that technical lignin derivative — vanillic acid are a promise
for obtaining polymer materials with good properties.