High-Pressure Low-Temperature Study of CaO(BO) ( = Pr, Nd, Gd, Er, Tm).

We investigated the site-disorder and thermal expansion of O(BO) ( = Pr, Nd, Gd, Er, Tm) through a single crystal structural study conducted between 100 and 300 K. Additionally, a high-pressure synchrotron X-ray diffraction study at low temperatures was conducted to determine the compressibility of both ordered and disordered prototype oxyborate lanthanides, specifically NdCaO(BO) and ErCaO(BO). The study revealed distinct behaviors consistent with their respective ionic radii.

Stability and Physical Properties of Metastable Ba-Si Clathrates.

In the present study, we have investigated the stability of different Ba-Si clathrates with pressure and temperature using DFT calculations and studied the stability of type I BaSi and type IX BaSi clathrates using high pressure─high temperature synthesis technique, calorimetry, and diffraction experiments. When increasing pressure, the type I BaSi clathrate and BaSi become more stable. In good qualitative agreement with experiments, the type IX BaSi clathrate becomes stable at a pressure of 1-2 GPa thanks to the pressure and thermal effect of both electronic and vibrational contributions.

Thermoelectric properties and lattice dynamics of tetragonal topological semimetal BaSi.

We report the lattice dynamics and thermoelectric properties of topological semimetal BaSi. The lattice dynamics has been studied by Raman and inelastic neutron scattering experiments. Good agreement has been found with first-principles calculations.

Effect of Nanostructuring on the Thermoelectric Properties of β-FeSi.

Nanostructured β-FeSi and β-FeCoSi specimens with a relative density of up to 95% were synthesized by combining a top-down approach and spark plasma sintering. The thermoelectric properties of a 50 nm crystallite size β-FeSi sample were compared to those of an annealed one, and for the former a strong decrease in lattice thermal conductivity and an upshift of the maximum Seebeck's coefficient were shown, resulting in an improvement of the figure of merit by a factor of 1.7 at 670 K.