Chlorine Nuclear Quadrupole Resonance in ErCl3 and Some Similar Chlorides

Abstract

In ErCl3 at 4.2°K the 35Cl NQR frequencies are 4.4566 ± 0.0002 and 4.5157 ± 0.0002 MHz and the asymmetry parameters η are 0.53 ± 0.02 and 0.52 ± 0.03 for the eightfold and fourfold sites, respectively. The electric field gradient xx principal axis at each site is within 4° of the bisector of the Er–Cl–Er angle. The above results are analyzed in a “bond-switching” scheme. We report also the 35Cl NQR frequencies in the trichlorides of Y, Dy, Ho, Tm, Yb, La, and U. The adequacy of the point-change model as the primary source of the electric field gradient in these ionic crystals is tested.