Site geometry of sodium compensated rare earth ions in calcium tungstate

Abstract A point charge calculation of the energy levels and selection rules for Yb 3+ ions in Ca 2+ sites in calcium tungstate gives fair agreement with those deduced by Pappalardo and Wood from optical absorption data. This new calculation differs from that published by Pappalardo and Wood in the correction of some errors and the incorporation of recent spin resonance data. Whereas the earlier calculation cast doubt upon the model of rare earth ions substituting into relatively undisturbed Ca 2+ sites, our calculation demonstrates that there is no such cause for doubt.