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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 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]

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]

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]

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 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]