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Thermodynamic properties of polycrystalline powders of ruthenium dichalcogenides have been studied using calorimetric isobaric heat capacity measurements in a wide temperature range. The adiabatic and differential scanning calorimetry data for ruthenium disulfide and ruthenium diselenide have been used to determine standard thermodynamic functions (heat capacity, entropy, enthalpy increment, and reduced Gibbs energy) of these compounds in the range 10–965 K. At 298.15 K, the functions of RuS2 are as follows: = 60.82 ± 0.12 J/(K mol), S° = 56.05 ± 0.11 J/(K mol), Н°(298.15 K) − Н°(0) = 9.75 ± 0.02 kJ/mol, and Ф° = 23.34 ± 0.05 J/(K mol). For RuSe2, we have obtained = 69.96 ± 0.14 J/(K mol), S° = 80.62 ± 0.16 J/(K mol), Н°(298.15 K) − Н°(0) = 13.05 ± 0.03 kJ/mol, and Ф° = 36.85 ± 0.08 J/(K mol). The data obtained above 298 K have been used to determine empirical coefficients of the Maier–Kelley and Khodakovsky equations. The absolute entropies obtained in this study for the ruthenium dichalcogenides, in combination with literature data, have made it possible to evaluate the Gibbs energy of formation of RuS2(cr) and RuSe2(cr) at 298.15 K. [ABSTRACT FROM AUTHOR]

In this paper, we report the synthesis of crystalline ruthenium ditelluride (RuTe2) and its thermodynamic properties in the range from 10 to 965 K, evaluated from its isobaric heat capacity Cp determined using calorimetry. At low temperatures, between 6.86 and 335.11 K, the heat capacity of the synthesized material—pure, free of impurities and foreign phases—was determined by adiabatic calorimetry. In the range 315.3–965.3 K, Cp was determined by differential scanning calorimetry. The data obtained above 298 K have been used to determine empirical coefficients of the Maier–Kelley and Khodakovsky equations. In the range 10–965 K, we have evaluated the standard thermodynamic functions: heat capacity, entropy, enthalpy increment, and reduced Gibbs energy. At 298.15 K, we have obtained = 72.43 ± 0.14 J/(K mol), S° = 94.94 ± 0.19 J/(K mol), Н°(298.15 K) − Н°(0) = 14.60 ± 0.03 kJ/mol, and Ф° = 45.97 ± 0.09 J/(K mol). Using the absolute entropy determined by us and data in the literature and handbooks, we have estimated the standard Gibbs energy of formation of RuTe2: ΔfG°(RuTe2, cr, 298.15) = −130.5 ± 2.9 kJ/mol. [ABSTRACT FROM AUTHOR]

In this paper, we report the synthesis of crystalline platinum ditelluride, PtTe2, a synthetic analog of the mineral moncheite, and its thermodynamic properties. Using the isobaric heat capacity of PtTe2 determined in the range 2–305 K by the relaxation and adiabatic calorimetry methods, we have evaluated its standard thermodynamic functions: entropy, enthalpy increment, and reduced Gibbs energy. The following parameters have been obtained for PtTe2 at 298.15 K: = 75.11 ± 0.15 J/(K mol), S° = 121.5 ± 0.2 J/(K mol), Н°(298.15 K) − Н°(0) = 16.69 ± 0.03 kJ/mol, and Ф° = 65.55 ± 0.13 J/(K mol). Using data in the literature and handbooks, we have estimated the standard Gibbs energy of formation of PtTe2: ΔfG°(PtTe2, cr, 298.15) = –75.4 ± 0.8 kJ/mol. Fractal analysis of the heat capacity data indicates that PtTe2 has a layered structure and that its Debye temperature is 250 K. [ABSTRACT FROM AUTHOR]

We have for the first time determined the temperature dependence of heat capacity for aurostibite, AuSb2, by adiabatic calorimetry and calculated its standard thermodynamic functions in a wide temperature range. At a temperature of 298.15 K, we have obtained = 76.01 ± 0.15 J/(mol K), S° = 133.4 ± 0.3 J/(mol K), Н°(298.15 K) − Н°(0)= 17.39 ± 0.03 kJ/mol, and Ф° = 75.02 ± 0.15 J/(mol K). Using previously reported data and the present results, we have found ΔfG°(298.15) = −11.36 ± 0.90 kJ/mol. [ABSTRACT FROM AUTHOR]

The temperature-dependent heat capacity of vysotskite, PdS, has been determined for the first time by adiabatic, relaxation, and differential scanning calorimetry in a wide temperature range and standard thermodynamic functions of PdS have been calculated. The 298.15-K values thus obtained are = 43.65 ± 0.09 J/(mol K), S° = 51.98 ± 0.10 J/(mol K), Н°(298.15 К) − Н°(0) = 8.03 ± 0.02 kJ/mol, and Ф° = 25.03 ± 0.05 J/(mol K). Using the present results and data in the literature, we obtained ΔfH°(PdS, 298.15 K) = –74.0 ± 1.0 kJ/mol and ΔfG°(PdS, 298.15 K) = –68.7 ± 1.0 kJ/mol. [ABSTRACT FROM AUTHOR]

The thermodynamic properties of crystalline platinum disulfide have been studied in the range from 5 to 875 K. The isobaric heat capacity of PtS2 has been determined by two methods: by adiabatic calorimetry from 5.32 to 344.96 K and by differential scanning calorimetry in the range 344.6–874.6 K. Using the experimental Cp(T) data, we evaluated the standard thermodynamic functions of platinum disulfide in a wide temperature range. The high-temperature Cp measurement results have been used to investigate regression models based on the Maier–Kelley and Khodakovsky equations for the temperature dependence of its isobaric heat capacity in the range from 298 to 875 K. The Debye characteristic temperature ΘD of PtS2 has been evaluated as a function of temperature. [ABSTRACT FROM AUTHOR]

The low-temperature heat capacity of DyO · 2ZrO and HoO · 2ZrO has been determined by adiabatic calorimetry in the temperature range 10-340 K. The results have been used to calculate the entropy, enthalpy increment, and reduced Gibbs energy of the zirconates without taking into account their low-temperature magnetic transformations. [ABSTRACT FROM AUTHOR]