EPR OF JAHN-TELLER CR2+ IN CAF2, BAF2 AND SRCL2

We study chromium-doped CaF2, BaF2 and SrCl2 using EPR. Cr2+ ions ente r the fluorite structure in a substitutional Jahn-Teller distorted sit e. In CaF2 the orthorhombic distortion is produced by two fluorine ion s placed in the plane perpendicular to the defect axis. In BaF2 and Sr Cl2 the distortion is tetragonal. Measurements in the three different planes using both X and Q-band and at temperatures between 4 and 300 K allow us to determine most of the spin Hamiltonian parameters includi ng those of hyperfine and superhyperfine interactions.