Narrow Results

The crystal structure and thermal properties of the ${\mathrm{\text{Ca}}}_{0.5}{\mathrm{\text{In}}}_{1.5}{\mathrm{\text{Se}}}_3$ compound have been investigated. Structural studies were performed by X-ray diffraction at room temperature. The crystal structure of this compound was found to correspond to the hexagonal symmetry of the space group P6₁. Thermal properties were studied using a differential scanning calorimetry (DSC). It was found in the temperature range $25^{\circ }\mathrm{\text{C}}\le T\le 950^{\circ }\mathrm{\text{C}}$ that thermal effects occur at temperatures $T_1=102^{\circ }\mathrm{\text{C}}$ and $T_2=848^{\circ }\mathrm{\text{C}}$. The thermodynamic parameters of these effects are calculated.

This paper discusses the results of the research carried out to study the structure, optical properties and thermophysical properties of a sample (nanopowder with a true density of 4.96 g/cm³, a particle size of 60 nm and a purity of 98.5%, SkySpring Nanomaterials, USA) with high purity. Based on the results of X-ray diffraction, the crystalline phase of MnFe₂O₄ ferrite nanoparticles was completely obtained and the values of the lattice parameters were determined. The results of the MID-IR analysis showed that the absorption coefficient $(\alpha )$ reaches its maximum value at 748 cm${}^{-1}$ wave number. The optical properties of the as-prepared nanostructures were also investigated by VERTEX 70 V diffuse reflectance spectroscopy (DRS). As can be seen from the results of the DSC analysis, the effects occurring in the temperature range up to $300^{\circ }$C clearly reflect the nature of the phase transitions and the amount of energy generated in the ferrite samples.

In this work, differential scanning calorimetric (DSC) analyses were performed in an Ar inert medium in the temperature range of 100–750 K for the Y₂O₃ compound with the purity rate of 99.99%, the density in powder form is 0.069 g/cm³, the specific surface area is 100–150 m²/g, the particle size is in the range of 8–10 nm irradiated with fast neutrons with different intensities ($E<1$ MeV). Using mathematical approximation methods, the equations of dependence of the heat flux function on temperature and heat capacity after irradiation at different intensities for the Y₂O₃ compound over a wide temperature range were determined. It was found that in the temperature range of $150\le T\le 750$ K, the value of the heat flux increases by 16.6%, up to 86 mW for the case of maximum radiation. At all radiation intensities, anomalies recorded with very small changes were observed in the spectra of the heat flux function related to the internal structural transitions.