Quadrupolar Relaxation of X Type Nuclei in R2MX6 and RMX3 Compounds

Abstract

Calculations of nuclear quadrupolar spin–lattice relaxation times are presented. The expressions obtained for the first order Raman and anharmonic Raman processes are applicable to a pure nuclear quadrupole resonance investigation of the X nuclei in R2MX6 and RMX3 solids. On the basis of realistic assumptions it is shown that the anharmonic Raman process will provide the dominant relaxation mechanism for these nuclei in these compounds. The relation between the spin–lattice relaxation time and the lattice dynamics is obtained explicitly without recourse to an assumed form of lattice vibrational normal mode spectrum. In favorable cases it is shown that the spin–lattice relaxation times can be related to Brillouin zone averaged rotary mode frequencies which are useful for the analysis of experimental data.