OPTICAL, EPR, AND ENDOR STUDIES OF CDF2 - V3+, V2+

Single crystals of CdF2 containing either V3+ or V2+ ions have been prepared and studied by optical, EPR, and ENDOR techniques. As expected, the properties of V3+ in the eight-coordinated (cubal) environment closely resemble those of Ni2+ in octahedral sites. The ENDOR data show that Ms=±1, confirming the identification of the ion as V3+. The V2+ ions, produced by heating samples containing V3+ in Cd vapor, exhibit evidence for a large trigonal Jahn-Teller distortion of the cubal site. On the basis of the EPR and optical data it is suggested that the environment about the V2+ ions may be more nearly octahedral than cubal, thus reflecting the presence of a static trigonal field comparable in magnitude to the (undistorted) cubic field. Some optical and EPR data are presented for isoelectronic Cr3+ ions, which also display a strong Jahn-Teller effect.