High-temperature heat capacity of Y2Cu2O5

The temperature dependence of the molar heat capacity of Y₂Cu₂O₅ has been measured at 328–953 K. The thermodynamic functions of the oxide compound have been calculated from the experimental data.     

High-temperature heat capacity of Dy2Cu2O5

Data on the heat capacity of Dy₂Cu₂O₅ in the temperature range 346–981 K have been obtained. The experimental data have been used for determining the thermodynamic properties of this oxide compound.     

High-temperature heat capacity of Gd2CuO4

The heat capacity of Gd₂CuO₄ has been studied by differential scanning calorimetry in the temperature range 362–958 K. It has been found that the temperature dependence of the molar heat capacity has an extremum near 590 K; the extremum is related to a phase transition from the high-temperature tetragonal phase to the low-temperature orthorhombic phase.     

High-temperature heat capacity of Bi2CuO4

The heat capacity of Bi₂CuO₄ has been measured over a wide temperature range. The thermodynamic functions of the solid oxide compound have been calculated using the experimental data.     

High-temperature heat capacity of La2CuO4

The heat capacity of La₂CuO₄ has been measured in the temperature range 400–950 K. The temperature dependence of the heat capacity has been found to exhibit an extremum at 526 K.     

High-temperature heat capacity of Y2.93Ho0.07Fe5O12

This paper presents data on the heat capacity of Y_2.93Ho_0.07Fe₅O₁₂ obtained in the temperature range 343?C1000 K. A correlation between the composition of the Fe₂O₃-Y₂O₃ pseudobinary system and the specific heat capacity of oxide compounds is pointed out.     

High-temperature heat capacity of Y2.9Ho0.1Al5O12

This paper presents data on the heat capacity of Y_2.9Ho_0.1Al₅O₁₂ as a function of temperature (360–1020 K). The experimental data obtained are used to derive the thermodynamic functions of the oxide compound.     

High-temperature heat capacity of CuGa2O4

Experimental data on the heat capacity of CuGa₂O₄ in the range 329–1050 K are presented. The values of the thermodynamic functions (enthalpy and entropy changes) are calculated from smoothed values of the heat capacity.     

High-temperature specific heat of Cu5Bi2B4O14

Cu₅Bi₂B₄O₁₄ single crystals are grown by spontaneous crystallization from a melt of a CuO, Bi₂O₃, and B₂O₃ mixture. The specific heat of the crystals in the temperature range 396–633 K is measured by differential scanning calorimetry. Using the experimental data, the thermodynamic properties of the Cu₅Bi₂B₄O₁₄ solid compound are calculated.     

Low temperature heat capacity of YBa2Cu3O7

We have measured the heat capacity of superconducting, single phase YBa₂Cu₃O₇ in the temperature range 2 to 18 K. An extrapolation of the data between 4 and 9 K gives aC/T (T → 0) of ∼ 25 mJ/mole K². The Debye temperature obtained from the high temperature linear portion ofC/T vsT ² plot is 325 K.     

Phonon spectra and heat capacity of Li2B4O7 and LiB3O5 crystals

The results of calculations of the phonon dispersion, the vibrational density of states and the heat capacity of lithium tetraborate and lithium triborate crystals are presented. They are obtained in the framework of a potential model that takes into account the non-equivalence of boron atoms in different structural positions (BO3 and BO4 units). A symmetry analysis of the phonon modes at point was performed, and calculated frequencies are compared to experimental spectra. Analysis of Li contributions to the vibrational density of states reveals that the Li-O bonds in both crystals are relatively weak. This is in line with the experimentally observed high mobility of lithium ions at high temperatures. A good agreement between calculated and measured heat capacities from the literature was obtained.     

High-temperature heat capacity of oxides in the Bi 2 O 3 -SiO 2 and Bi 2 O 3 -GeO 2 systems

Experimental data on the heat capacity of the Bi₂SiO₅ oxide compound and eutectic compositions 75 mol % Bi₂O₃ + 25 mol % SiO₂ and 65 mol % Bi₂O₃ + 35 mol % GeO₂ have been obtained for a wide temperature range.     

High-temperature heat capacity of CuGeO3 and Cu0.9Yb0.1GeO3

Data on the heat capacity of CuGeO₃ and Cu_0.9Yb_0.1GeO₃ have been obtained in a wide temperature range. Their thermodynamic properties have been calculated from experimental data.     

High-temperature heat capacity of BaFe12O19 and BaSc0.5Fe11.5O19

Physics of the Solid State - Data on the heat capacity of BaFe12O19 (373–1450 K) and BaSc0.5Fe11.5O19 (408–1000 K) have been obtained. In the temperature dependences of the heat...     

Copper and oxygen vibrations in La2CuO4 and YBa2Cu3O7

We perform eV neutron scattering experiments (neutron energy > 1 eV) on copper metal, CuO, La₂CuO₄ and YBa₂Cu₃O₇, and neutron absorption experiments of HoBa₂Cu₃O₇, and determined the mean kinetic energy of O, Cu and other atoms in these materials. The Debye temperatures of Cu atoms in La₂CuO₄ and YBa₂Cu₃O₇ were estimated to be extremely large, about 1500 and 2000 K, respectively.     

High-temperature heat capacity of YFe3(BO3)4

The molar heat capacity of YFe₃(BO₃)₄ has been measured using differential scanning calorimetry in the temperature range 339–1086 K. It has been found that the dependence C _p = f(T) exhibits an extremum at a temperature of 401 K due to the structural transition.     

High-temperature heat capacity of TbFe3(BO3)4

The molar heat capacity of TbFe₃(BO₃)₄ in the temperature range of 346–1041 K has been measured by differential scanning calorimetry. It has been found that the C _p = f(T) curve does not show extremes. The thermodynamic properties of the oxide compound have been determined from the experimental data.     

Infrared and Raman spectra of M2Cu2O5 (M=Y,Ho)

We report both Raman and infrared reflectivity spectra of M₂Cu₂O₅ (M=Y, Ho) at room temperature in the spectral range of 30–1000 cm^–1.37 (31) ir and 18 (15) Raman active modes of Y₂Cu₂O₅ (Ho₂Cu₂O₅) are observed. A factor group analysis has been performed to identify the symmetries of the observed modes. Comparing the vibrational spectra of these compounds we conclude that the phonons above 300 cm^–1 originate from the Cu–O vibrations and those under 300 cm^–1 from M–O vibrations.Alexander von Humboldt Foundation fellow     

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.