PHONON-DISPERSION MEASUREMENTS AT HIGH-PRESSURES TO 7 GPA BY INELASTIC NEUTRON-SCATTERING

A novel technique for the investigation of phonon dispersion curves by inelastic neutron scattering under high pressure is presented. The method uses tungsten carbide (WC) opposed anvils with a spheroidal pressure chamber, to compress samples embedded in NaCl by a hydraulic press of 250 tons capacity. The potential of the technique is illustrated by measurements of transverse acoustic phonons of germanium and Fe3Pt up to 7 GPa. Typical scan times were 2-3 h. It is shown that accurate determinations of mode Grüneisen parameters are possible and suggest that similar studies using this technique may be feasible for a wide range of solids to pressures beyond 10 GPa.© 1995 American Institute of Physics.