ELECTRON-PARAMAGNETIC-RESONANCE AND RELAXATION STUDY OF COPPER(II) AND SILVER(II) IN CSCDF3 SINGLE-CRYSTALS

Copper and silver, respectively, were introduced into single crystals of CsCdF3. Our detailed electron paramagnetic resonance (EPR) study sh owed that both elements enter the Cd lattice site-copper as Cu2+, silv er as Ag+, which then was converted into Ag2+ by x raying the correspo nding samples. Cu2+ and Ag2+ were shown to present in their ground sta te a pseudo-static Jahn-Teller effect. Motional effects were observed in the respective EPR spectra and studied in some detail for Cu2+ as t hey are seen over a wide temperature range. Predictions of a stochasti c Kubo model [J. Phys. Soc. Jpn. 9, 935 (1954)] were compared with the temperature dependent linewidths of the motionally averaged EPR spect rum. A power law (T(n) with n congruent-to 1.9) was determined for the temperature dependence of the reorientation frequency between 30 and 90 K.