ELECTRON-PARAMAGNETIC RESONANCE STUDIES OF GD3+ IN KZNF3 AND KCDF3

EPR investigations of Gd3+ impurity ions in KZnF3 and KCdF3 have been made at the temperatures 487, 300, 77 and 4.2 K for KZnF3 and at 487 K for KCdF3. The spectra for cubic symmetry have been observed and the spin Hamiltonian parameters in cubic crystalline field have been determined. At the temperature of 487 K, the fourth-order zero-field splitting parameters in the spin Hamiltonian show remarkable difference for both crystals as following values: |b4|=-6.97×10-4cm-1 for KZnF3 and |b4|=1.6×10-4 cm-1 for KCdF3. This difference implies that Gd3+ impurities substitute for different cubic sites. From the size consideration of the ionic radii among K+, Zn2+, Cd2+ and Gd3+, it is concluded that Gd 3+ substitute for 12-fold K+ site in KZnF3 and 6-fold Cd2+ site in KCdF3. © 1979, THE PHYSICAL SOCIETY OF JAPAN. All rights reserved.