Local structure of the trigonal defect center for Cr3+ ions in KMgF3 crystals

The zero-field splitting D, the anisotropic g-factors g(parallel to), Delta g(= g(parallel to) - g(perpendicular to)) and the first excited state splitting Delta(E-2) for the trigonal Cr3+-V-K center in KMgF3:Cr3+ crystals have been studied from Macfarlane's high-order perturbation formulas. From the studies, the local structure of the trigonal center is obtained. The local lattice distortions (i.e., the displacement directions of the ions in the center) are consistent with the expectation based on the electrostatic interaction.