Program > Browse abstracts by speaker > Yoshiasa Akira

Single crystal structural analyses of various pyrite-type compounds were performed by selecting single crystals from synthetic and natural mineral crystals. Even in many cases where single-phase synthesis is difficult, single crystals with several microns are often obtained. Structure analysis is possible even at a crystal size of a few microns with high-intensity X-rays. The Debye temperature for each atom can be estimated using the dynamic component in Debye-Waller factor [1-3]. The Debye temperatures obtained from the Debye-Waller factor, the neutron inelastic scattering, the elastic constant and the low temperature heat capacity usually show good agreements [1-3]. The phonon energies estimated from lattice dynamics calculations coincides well with the values from Debye temperatures. Debye temperature correlates with the melting temperature, formation temperature, thermal conductivity, atomic diffusion and the hardness of materials.

The Debye temperatures of RuS2 and OsS2 are 661 K and 688 K, respectively. In the rhodium-containing erlichmanite–laurite solid solutions (Os1–x–yRuxRhyS2: x = 0.09–0.60, y = 0.07–0.10), substitution of Ru by Os with 10 at.% Rh significantly lowered the Debye temperature by as much as 170 K [3]. The minor component Rh has a significant effect on the thermal stability of OsS2, and these effects are different between OsS2 and RuS2. RuS2 and OsS2 have melting points of over 1700K. The Debye temperatures of both atoms in PtSb2, AuSb2 and AuTe2 were found to be very low among the transition metal pnictide and chalcogenides. Although the Debye temperatures vary widely among these compounds, some interesting regularities are observed [1-3].