Synthesis,Crystal Structure,and Thermal Properties of Substituted Titanates Bi2Pr2Ti3O12 and Bi2Nd2Ti3O12

Physics of the Solid State - Titanates Bi2Pr2Ti3O12 and Bi2Nd2Ti3O12 have been obtained by the solid-phase synthesis using sequential annealing of the Bi2O3, Nd2O3, Pr6O11, and TiO2 stoichiometric...     

High-Temperature Heat Capacity of Zn<Subscript>2</Subscript>V<Subscript>2</Subscript>O<Subscript>7</Subscript>–Cu<Subscript>2</Subscript>V<Subscript>2</Subscript>O<Subscript>7</Subscript> Solid Solutions

Differential scanning calorimetry has been used to study the influence of temperature on the heat capacity of synthesized vanadates Zn₂V₂O₇, (Cu_0.56Zn_1.44)V₂O₇, and (Cu_1.0Zn_1.0)V₂O₇. It is found that dependences C_p = f(T) have extremes. The thermodynamic properties of Zn₂V₂O₇ have been determined.     

High-temperature specific heat of Bi2GeO5 and SmBiGeO5 compounds

The SmBiGeO₅ compound is synthesized from Sm₂O₃, Bi₂O₃, and GeO₂ by solid-state synthesis with subsequent annealing at 1003, 1073, 1123, 1143, 1173, and 1223 K. The metastable Bi₂GeO₅ compound is prepared from melt. Temperature dependences of specific heat of Bi₂GeO₅ (350–1000 K) and SmBiGeO₅ (370–1000 K) are measured by differential scanning calorimetry. Basing on the experimental dependences C _P = f(T), the thermodynamic functions of the oxide compounds are calculated.

     

High-temperature heat capacity of CdO–V2O5 oxides

Vanadates Cd₂V₂O₇ and CdV₂O₆ have been prepared from CdO и V₂O₅ by three-phase synthesis with subsequent burning at 823–1073 K and 823–853 K, respectively. The molar heat capacity of these oxide compounds has been measured by differential scanning calorimetry. The enthalpy change, the entropy change, and the reduced Gibbs energy are calculated using the experimental dependences C _p = f(T). It is shown that there is a correlation between the specific heat capacity and the composition of CdO–V₂O₅ oxide system.

     

High-Temperature Specific Heat of the TmBiGeO<Subscript>5</Subscript> and YbBiGeO<Subscript>5</Subscript> Compounds

The TmBiGeO₅ and YbBiGeO₅ compounds have been synthesized from Tm₂O₃ (Yb₂O₃), Bi₂O₃, and GeO₂ oxides by the solid-state synthesis with successive burning at 1003, 1073, 1123, 1143, 1173, and 1223 K. High-temperature specific heat of the oxide compounds has been measured by differential scanning calorimetry. Basing on the experimental dependences C_p = f(T), the thermodynamic properties of the oxide compounds, i.e., the enthalpy and entropy variations, have been calculated.     

High-temperature heat capacity of oxides of the CuO–V2O5 system

CuV₂O₆ and Cu₂V₂O₇ compounds have been produced from initial components CuO and V₂O₅ by solid-phase synthesis. The high-temperature heat capacity of the oxide compounds has been measured using differential scanning calorimetry. The thermodynamic properties (the enthalpy change, the entropy change, and the reduced Gibbs energy) have been calculated using experimental dependences C _P = f(T). It is found that there is a correlation between the specific heat capacity and the composition of oxides of the CuO–V₂O₅ system.

     

Synthesis,Structure, and Thermophysical Properties of Pb10 – xBix(GeO4)2 + xVO4)4 – x (x = 0–3) in the Temperature Range of 350–950 K

Physics of the Solid State - The Pb10&nbsp;–&nbsp;xBix(GeO4)2&nbsp;+&nbsp;x(VO4)4&nbsp;–&nbsp;x (x = 0–3) compounds with an apatite structure have been...     

High-temperature heat capacity of Pb<Subscript>8</Subscript>La<Subscript>2</Subscript>(GeO<Subscript>4</Subscript>)<Subscript>4</Subscript>(VO<Subscript>4</Subscript>)<Subscript>2</Subscript> in the range 320–1000 K

The oxide compound Pb₈La₂(GeO₄)₄(VO₄)₂ with an apatite structure has been synthesized by a ceramic method. The effect of temperature on the molar hear capacity of polycrystalline samples in the temperature range 320–1000 K has been studied by differential scanning calorimetry. The results have been used to calculate the thermodynamic functions of the synthesized compound.     

High-temperature heat capacity of YBiGeO5 and GdBiGeO5 in the range 373–1000 K

The oxide YBiGeO₅ and GdBiGeO₅ compounds have been synthesized by solid-phase synthesis. The high-temperature heat capacity has been measured using differential scanning calorimetry in the range 373–1000 K. The results were used to calculate the thermodynamic properties (the change in the enthalpy and entropy).

     

Heat capacity of GdBiGeO<Subscript>5</Subscript> in the temperature range 373–1000 K

Ternary oxide GdBiGeO₅ was synthesized by a ceramic method. The heat capacity of crystalline gadolinium bismuth germanate as a function of temperature in the range 373–1000 K has been studied by differential scanning calorimetry. It has been demonstrated that the temperature dependence of the heat capacity can be described by the classical Maier–Kelley equation. From the experimental C _P = f(T) data, the thermodynamic functions (the change in enthalpy and entropy) of ternary oxide GdBiGeO₅ have been calculated.