THE STRUCTURAL Re-ARRANGEMENT IN CaF₂ DUE TO TRIVALENT RARE EARTH IMPURITY IONS

First-Principles Study on Structural Properties and 4f → 5d Transitions of Locally Charge-Compensated Ce3+ in CaF2

“…The four nearest-neighbor (NN) F – ions between Ce 3+ and F i ′ move outward while the other four NN F – ions, on the opposite side, move inward. Such a distortion pattern is in good agreement with the structural pictures of the charge-compensated tetragonal Ce 3+ and Pr 3+ centers in CaF 2 , obtained using electron nuclear double resonance (ENDOR) , and RF-optical double resonance measurements, respectively. The bond lengths from Ce 3+ to the four NN F – ions near the F i ′ are smaller by 0.057 Å than those to the other four NN F – ions.…”