Thermodynamic and kinetic properties of an icosahedral quasicrystalline phase in the Al-Pd-Tc system

The properties of a quasicrystalline phase in the Al-Pd-Tc system are studi ed for the first time. X-ray investigations demonstrate that the quasicryst alline phase in the Al70Pd21Tc9 alloy has a face-centered icosahedral quasi -lattice with parameter a = 6.514 Angstrom. Annealing experiments have reve aled that this icosahedral phase is thermodynamically stable. The heat capa city of an Al70Pd21Tc9 sample is measured in the temperature range 3-30 K. The electrical resistivity and magnetic susceptibility are determined in th e temperature range 2-300 K. The electrical resistivity is found to be high (600 mu Omega cm at room temperature), which is typical of quasicrystals. The temperature coefficient of electrical resistivity is small and positive at temperatures above 50 K and negative at temperatures below 50 K. The ma gnetic susceptibility has a weakly paramagnetic character. The coefficient of linear contribution to heat capacity (gamma = 0.24 mJ/(g-atom K-2)) and the Debye characteristic temperature (Theta = 410 K) are determined. The or igin of the specific features in the vibrational spectrum of the quasicryst als is discussed. (C) 2000 MAIK "Nauka/Interperiodica".