EPR STUDY OF NI-2+-VACANCY DIPOLES IN LICL CRYSTALS

The paramagnetic resonance spectra of Ni2+ in LiCl have been studied at 9 GHz. Two kinds of Ni2+ centers associated with positive ion vacancy in their nearest or next nearest neighbour position are observed. Their spin Hamiltonian parameters are determined to be gx=2.27±0.04, gy=2.26±0.02, gz=2.31±0.01, |D|=0.564±0.002 cm−1, |E|=0.080±0.002 cm−1, and g⁄⁄=2.360±0.005, g⊥=2.30±0.05, |D|=3.1±0.3 cm−1 and |E|≃0.0 cm−1. The Ni2+-vacancy dipoles aggregated to form clusters and the isolated dipoles decayed in number. The decay constant of third order rate process is about 1.2×105 h−1 (mole fraction)−2 at room temperature. The EPR line width depends upon the crystal orientation. Interaction between near neighbour dipoles contributed to this anisotropic line width. © 1979, THE PHYSICAL SOCIETY OF JAPAN. All rights reserved.