N. P. Gorbachuk

Heat Capacity and Enthalpy of Lu5Ge3 at 57-2355 K

The thermal capacity and enthalpy of Lu5Ge3 have been examined over a wide temperature range. Low-temperature thermal-capacity measurements have been used to calculate the enthalpy, entropy, and reduced Gibbs energy of the germanide under standard conditions. The coefficients in the temperature dependence of the thermodynamic functions have been determined for the interval 298.15-2355 K. The melting point and enthalpy and entropy of melting of the compound have been determined.

Thermodynamic properties of praseodymium germanides in the range 55–1940 K

The heat capacity and enthalpy of Pr5Ge3, PrGe, and PrGe1.8 were investigated over a wide temperature range for the first time. The temperatures, enthalpies, and entropies of melting of these compounds, and of the polymorphic transformation in PrGe1.8 were determined. Temperature dependencies of the basic thermodynamic functions were calculated and are recommended for practical use.

Thermodynamic characteristics of rare-earth monosilicides at high temperatures

The heat capacity components for some rare-earth monosilicides experimentally studied in the range of middle and high temperatures are analyzed. Patterns of variation in temperatures and enthalpies of melting in a series of compounds from LaSi to LuSi are established. An equation is proposed to determine the high-temperature heat capacity Cp. The melting enthalpies and entropies are calculated for eight LnSi compounds that are still to be experimentally studied (Ln = Ce, Nd, Pm, Sm, Tb, Dy, Ho, Tm).

Melting enthalpies and high-temperature heat capacities of lower silicides of YTTRIUM-subgroup rare-earth metals

Components of the high-temperature heat capacity of REM silicides, Ln5Si3, and variation in their melting enthalpies in the Gd5Si3 → Ln5Si3 series are analyzed. A method for calculating the high-temperature thermodynamic properties of the compounds still to be experimentally studied is proposed. The experimental temperature dependences for the enthalpies of Ln5Si3 (Ln = Gd, Er, Lu) are used to calculate the melting enthalpies and temperature dependences of the heat capacity for other yttrium-subgroup silicides.

Thermodynamic Properties of Y5Sn3 over a Wide Range of Temperature

The heat capacity and enthalpy of Y5Sn3 were investigated in the temperature range 58-2294 K for the first time. Values of the standard enthalpy, entropy, and reduced Gibbs energy of the stannide were calculated from the low-temperature heat capacity data. The temperature dependencies of the thermodynamic functions for the solid state of Y5Sn3 in the range 298.15-2300 K were found. The temperature, enthalpy, and entropy of melting of the compound were determined.

Heat Capacity of Dysprosium Germanides at 55-300 K

The heat capacities of Dy5Ge3, DyGe, and DyGe2 at low temperatures were determined by an adiabatic method for the first time, and the enthalpies, entropies and reduced Gibbs energies at 298.15 K calculated.

High-Temperature Enthalpy of La 2 Hf 2 O 7 in the Temperature Range 490–2120 K

Lanthanum hafnate La2Hf2O7 was produced chemically by inverse precipitation from ammonia solution and a mixture of La and Hf nitrates, followed by hydroxide decomposition at 1250°C in air and melting of the oxide mixture in a solar furnace. The formation of La2Hf2O7 was ascertained by X-ray diffraction. The La2Hf2O7 enthalpy increment was measured in the range 490–2120 K (for the first time in the temperature ranges 490–988 K and 1740–2120 K) by drop calorimetry using a Setaram HT-1500 high-temperature differential calorimeter and a high-temperature calorimetric device. A fitted equation for the enthalpy increment was used to calculate the main thermodynamic functions (heat capacity, entropy, and Gibbs energy) in the temperature range 298–2120 K. The experimental results are compared with the published data and those assessed using the Neumann–Kopp rule.