Phonon Dispersion in the Layered Compound PbI₂

Abstract

Abstract Phonon dispersion curves up to a frequency of 2.5 THz have been measured by inelastic neutron scattering in a sample of Pbl 2 with D structure for the three principal symmetry directions. No appreciable two‐dimensional character has been detected in the dispersion of the acoustic modes, and the elastic constants derived from the measurements show only slight anisotropy. Comparisons are made of the present optic mode determination with previous measurements.