ELECTRON SPIN RESONANCE OF CU2+ AND NI2+ IONS IN ZINC TUNGSTATE

Electron spin resonance spectra of the Cu2+ ion in zinc tungstate are consistent with a spin-Hamiltonian with parameters: gx = 2·341±0·002, gy = 2·382± 0·002, gz = 2·001±0·001; Ax = -9·2±0·3, Ay = -19·3±0·4, Az = 76·5±0·5; Q = - 10·9±0·3, Qprime = -0·65±0·05. The units of A and Q are 10-4 cm-1. For the Ni2+ ion, the parameters are: gxsimilar, equalsgy = 2·15±0·02, gz = 2·250±0· 003; D = -(15±2) cm-1, E = (0·151±0·001) cm-1. Crystals containing Cu2+ were produced by both flux-melt and Czochralski techniques and a correlation between linewidth and crystal perfection was observed. Spin-lattice relaxation rates determined in the helium temperature range were represented by direct and Raman terms: the extrapolations of these rates were not in good accord with values deduced from linewidths at higher temperatures.