EPR and optical absorption study of Cr 3+ doped diammonium hexaaqua magnesium sulphate single crystal

Abstract

EPR measurements of Cr 3+ doped diammonium hexaaqua magnesium sulphate single crystals are made at room temperature. The crystal field and spin Hamiltonian parameters are evaluated from the resonance lines obtained at different angular orientations. The value of g = 1.9763 ± 0.0002 and D = 611 ± 2 × 1 0 − 4 cm − 1 are evaluated. On the basis of EPR data the site symmetry of Cr 3+ in the crystal is discussed. Optical absorption studies of single crystals are also carried out at room temperature. The orbital energies of the chromium ion are estimated from the optical absorption spectrum. The different bonding parameters are obtained by correlating optical and EPR data and the nature of bonding in the crystal is discussed. The values of Racah parameters ( B and C ), crystal field parameter ( D q ) and nephelauxetic parameters ( h and k ) are obtained as B = 676 , C = 3371 , D q = 2043 cm − 1 , h = 1.258 and k = 0.21 .