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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]

Lithium sodium tetragermanate, LiNaGe4O9, has been prepared by solid-state reaction, by sequentially firing stoichiometric mixtures of Li2CO3, Na2CO3, and GeO2 starting materials in air in the temperature range 773–1073 K. Its unit-cell parameters have been determined by X-ray diffraction: a = 4.68007(3) Å, b = 9.3220(8) Å , c = 15.900(2) Å, and V = 694.113 Å (Z = 4, sp. gr. Pcca). The high-temperature heat capacity of the germanate has been determined using differential scanning calorimetry in the temperature range 320–1050 K. The experimental temperature-dependent heat capacity data, Cp(T), have been used to calculate the principal thermodynamic functions of LiNaGe4O9. [ABSTRACT FROM AUTHOR]

The RGaTi2O7 (R = Sm, Ho, Tm, Yb) substituted titanates have been prepared by solid-state reactions, by firing mixtures of the Ga2O3, TiO2, and R2O3 oxides in air at 1273 and 1573 K, and their crystal structure has been determined using X-ray diffraction. The effect of temperature (320–1000 K) on the heat capacity of the synthesized compounds has been studied by differential scanning calorimetry. The experimental Cp(T) data have been used to calculate the principal thermodynamic functions of the titanates. Using the group contribution method, we evaluated the standard enthalpy and Gibbs energy of formation of the RGaTi2O7 (R = Sm, Ho, Tm, Yb) titanates. [ABSTRACT FROM AUTHOR]

The heat capacity and volumetric characteristics of 0.20Bi2O3⋅хBaO⋅(0.80 – х)B2O3 glasses containing 5, 10, 15, and 20 mol % BaO have been measured in the temperature range 300–1000 K. The results, in combination with the glass transition characteristics found, have been used to calculate the standard thermodynamic functions (Т), H°(T) − (0), S°(T) − (0), and G°(T) − (0); density ρ(T); and thermal expansion coefficient α(T) in the range from T → 0 to 900 K for the glasses and supercooled melts. Having a broad transmission window, as demonstrated by our spectroscopic measurements, the glasses have high crystallization resistance according to differential scanning calorimetry results. [ABSTRACT FROM AUTHOR]

The CaY2Ge3O10 and CaY2Ge4O12 germanates have been synthesized by a standard ceramic processing route using CaCO3, Y2O3, and GeO2 as starting materials, and their crystal structure has been refined by X-ray diffraction. The high-temperature (350–1000 K) experimental heat capacity data obtained for the germanates by differential scanning calorimetry have been used to calculate their principal thermodynamic functions. [ABSTRACT FROM AUTHOR]

Pb10 –xEux(GeO4)2 +x(VO4)4 –x (x = 0.1, 0.2, 0.3) Eu-substituted lead germanatovanadates with the apatite structure have been prepared by solid-state reactions, via firing in air in the temperature range 773–1073 K, using oxides (PbO, Eu2O3, GeO2, and V2O5) as starting materials. Using X-ray diffraction, we have determined the hexagonal cell parameters (sp. gr. P63/m) of the synthesized phases and refined their crystal structure (the atomic position coordinates, isotropic thermal parameters, and principal bond lengths in their structure are presented). We have measured the luminescence spectra of the Pb10 –xEux(GeO4)2 +x(VO4)4 –x (x = 0.1, 0.2, 0.3) apatites and shown that europium concentration has little effect on the shape of the luminescence spectra. Using experimental heat capacity data obtained for polycrystalline samples by differential scanning calorimetry in the temperature range 350–1050 K, we calculated the main thermodynamic functions of the Eu-substituted lead germanatovanadates. [ABSTRACT FROM AUTHOR]

Bi4–xPrxTi3O12 (x = 0.4, 0.8, 1.2, 1.6) solid solutions have been prepared by solid-state reactions, via multistep firing of stoichiometric mixtures of their constituent oxides in air at temperatures from 1003 to 1323 K. Their crystal structure has been determined using X-ray diffraction, and their luminescence spectra have been measured at room temperature. High-temperature heat capacity of polycrystalline substituted bismuth titanate samples has been determined by differential scanning calorimetry. The Cp(T) curves of the solid solutions with x = 0.4 and 0.8 have extrema related to phase transitions. Experimental data have been used to calculate the main thermodynamic functions of the solid solutions. [ABSTRACT FROM AUTHOR]

The DyGaTi2O7 and EuGaTi2O7 titanates have been prepared by solid-state reactions in a starting mixture of Dy2O3 (Eu2O3), Ga2O3, and TiO2 via firing in air at temperatures of 1273 and 1573 K, and their crystal structure has been studied by X-ray diffraction. Their high-temperature heat capacity (350–1000 K) has been determined by differential scanning calorimetry. The Cp(T) experimental data have been used to calculate the thermodynamic functions of the titanates. [ABSTRACT FROM AUTHOR]

Single-phase LuGaTi2O7 samples have been prepared by solid-state reaction in a starting mixture of Lu2O3, Ga2O3, and TiO2 via sequential firing in air at temperatures of 1273 and 1573 K. The crystal structure of the lutetium gallium dititanate has been determined by the Rietveld method (profile analysis of X-ray diffraction patterns of polycrystalline powders): sp. gr. Pcnb; a = 9.75033(13) Å, b = 13.41425(17) Å, c = 7.29215(9) Å, V = 957.32(2) Å3, d = 6.28 g/cm3. The heat capacity of LuGaTi2O7 has been determined as a function of temperature by differential scanning calorimetry in the range 320–1000 K. The Cp(T) data thus obtained have been used to calculate the principal thermodynamic functions of the oxide compound. [ABSTRACT FROM AUTHOR]

Pb10 –xPrx(GeO4)2 +x(VO4)4– x (x = 0, 1, 2, 3) apatites have been prepared by solid-state reactions via sequential firing of appropriate oxide mixtures (PbO, Pr2O3, GeO2, and V2O5) in air in the temperature range 773–1073 K. Their unit-cell parameters have been determined as functions of temperature by high-temperature X-ray diffraction measurements, and the linear and volume expansion coefficients of Pb7Pr3(GeO4)5(VO4) have been calculated. The heat capacity of the synthesized Pb10 –xPrx(GeO4)2 +x(VO4)4– x (x = 0, 1, 2, 3) compounds with the apatite structure has been determined by differential scanning calorimetry in the temperature range 350–1050 K. The cp(T) curves of the samples with x = 1, 2, and 3 have been shown to have extrema (in particular, peaks at 701, 917, and 1018 K for the x = 3 sample) due to phase transitions. The experimental Cp(T) heat capacity data have been used to evaluate the thermodynamic functions of the synthesized apatites. [ABSTRACT FROM AUTHOR]

The europium gallium germanate EuGaGe2O7 has been prepared by solid-state reaction in air in the temperature range 1273–1473 K using a stoichiometric mixture of Eu2O3, Ga2O3, and GeO2. Its crystal structure has been determined by X-ray diffraction (sp. gr. P21/c, a = 7.1693(7) Å, b = 6.57008(6) Å, c = 12.7699(1) Å, β = 117.4522(5)°, V = 533.768(8) Å3). The heat capacity of polycrystalline samples has been determined by differential scanning calorimetry in the temperature range 350–1053 K and the experimental data have been used to calculate the thermodynamic properties (enthalpy increment, entropy change, and reduced Gibbs energy change) of EuGaGe2O7. [ABSTRACT FROM AUTHOR]

The europium gallium germanate EuGaGe2O7 has been prepared by solid-state reaction in air in the temperature range 1273–1473 K using a stoichiometric mixture of Eu2O3, Ga2O3, and GeO2. Its crystal structure has been determined by X-ray diffraction (sp. gr. P21/c, a = 7.1693(7) Å, b = 6.57008(6) Å, c = 12.7699(1) Å, β = 117.4522(5)°, V = 533.768(8) Å3). The heat capacity of polycrystalline samples has been determined by differential scanning calorimetry in the temperature range 350–1053 K and the experimental data have been used to calculate the thermodynamic properties (enthalpy increment, entropy change, and reduced Gibbs energy change) of EuGaGe2O7. [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]

Lanthanum stannate with the pyrochlore structure and a crystallite size in the range 100–400 nm has been prepared by solid-state synthesis. We have optimized synthesis parameters for obtaining a ceramic material. The heat capacity of La2Sn2O7 has been determined for the first time using adiabatic and differential scanning calorimetry techniques in the range 19–1300 K, and the stannate has been shown to undergo no structural transitions in this range. We have calculated temperature-dependent standard thermodynamic functions of La2Sn2O7 and evaluated the standard Gibbs energy of formation of this compound from its constituent elements at 298.15 K. [ABSTRACT FROM AUTHOR]

Gadolinium germanate, Gd2Ge2O7, has been prepared by solid-state reaction, via multistep firing in the temperature range 1273–1473 K, and its high-temperature heat capacity has been determined by differential scanning calorimetry. The Cp(T) data have been used to evaluate the thermodynamic functions (enthalpy increment, entropy change, and reduced Gibbs energy) of the oxide compound. [ABSTRACT FROM AUTHOR]

The Gd2Ti2O7 and Lu2Ti2O7 titanates (pyrochlore structure, sp. gr. Fd3m) have been prepared by solid-state reactions in air at temperatures from 1673 to 1773 K using the Gd2O3, Lu2O3, and TiO2 oxides as starting materials. Their high-temperature heat capacity has been determined by differential scanning calorimetry in the range 350–1000 K. The experimental heat capacity data have been used to evaluate the thermodynamic functions of gadolinium and lutetium dititanates. [ABSTRACT FROM AUTHOR]

Oxides Y0.65Pr0.35BiGeO5 and Y0.65Nd0.35BiGeO5 have been synthesized by a ceramic method. The heat capacity of fine crystalline samples has been studied in the range 350-1000 K by differential scanning calorimetry. The Cp = f(T) dependences can be described by the Maier-Kelley equation. The thermodynamic functions of these oxides—changes in enthalpy, entropy, and reduced Gibbs energy—have been calculated from the experimental data on high-temperature heat capacity. [ABSTRACT FROM AUTHOR]

ErInGe2O7 and TbInGe2O7 have been synthesized from the parent oxides by a ceramic method through the multistep annealing in air in the temperature range 1273–1473 K. The high-temperature heat capacity of these oxides has been measured by the differential scanning calorimetry method (350–1000 K). Their thermodynamic properties have been calculated from the experimental dependences Cp = f(T). [ABSTRACT FROM AUTHOR]

The heat capacity of InVO has been determined by differential scanning calorimetry in the temperature range 339-1089 K. The experimental C( T) data have been used to evaluate the thermodynamic functions of indium orthovanadate: enthalpy increment H°( T)- H°(339 K), entropy change S°( T)- S°(339 K), and reduced Gibbs energy Ф°( Т). The specific heats of GaVO and TlVO have been evaluated. [ABSTRACT FROM AUTHOR]

Critical evaluation and optimization of all available phase diagrams and thermodynamic data for the Mn-RE (RE = Tb, Dy, Ho, Er, Tm, and Lu) systems has been conducted to obtain reliable thermodynamic functions of all the phases in the systems. Key experiments for the Mn-Dy system were performed using DSC and solution calorimeter. In the thermodynamic modeling, it is found that the Mn-RE systems show systematic changes in the phase diagrams and thermodynamic properties such as enthalpy of mixing in liquid state in the order of periodic number in the lanthanide series. The systematic thermodynamic modeling approach for RE elements allow to resolve inconsistencies in the experimental data and estimate unknown thermodynamic properties and phase equilibria of Mn-RE system. [ABSTRACT FROM AUTHOR]

The heat capacity of InCuO has been determined by differential scanning calorimetry in the temperature range 364-984 K. The C( T) data have been used to evaluate the thermodynamic functions of indium cuprate: enthalpy increment H( T) - H(364 K) and entropy change S( T) − S(364 K). [ABSTRACT FROM AUTHOR]

The heat capacity of ɛ-GaSe has been determined by differential scanning calorimetry in the temperature range 300-700 K. Smoothed heat capacity data have been used to evaluate the thermodynamic functions of gallium monoselenide (entropy, enthalpy increment, and reduced Gibbs energy). [ABSTRACT FROM AUTHOR]

GdSnO gadolinium stannate with the pyrochlore structure has been prepared by solid-state reaction and its high-temperature heat capacity has been determined by differential scanning calorimetry in the temperature range 350-1020 K. The C( T) data are shown to be well represented by the classic Maier-Kelley equation. The experimental C( T) data have been used to evaluate the thermodynamic functions of gadolinium stannate: enthalpy increment H°( T)- H°(339 K), entropy change S°( T)- S°(339 K), and reduced Gibbs energy Ф°( Т). [ABSTRACT FROM AUTHOR]

The effect of temperature within the range 379-1026 K on the specific heat of thulium orthovanadate TmVO obtained by solid-phase synthesis was studied by differential scanning calorimetry. From the experimental dependence C = f( T), which is described by the equation C = (136.46±0.47) + (15.5±0.5) × 10 T - (17.5±0.6) × 10T, the thermodynamic functions of the oxide compound were calculated. [ABSTRACT FROM AUTHOR]