Awadhesh Kumar Yadav

Superposition model study of Cr3+ doped tetra methyl ammonium cadmium chloride

The zero field splitting parameter D of Cr(3+) doped in tetra methyl ammonium cadmium chloride (TMCC) is calculated with perturbation formula using microscopic spin Hamiltonian theory and crystal field parameters from superposition model. The theoretically calculated ZFS parameter for Cr(3+) in TMCC single crystal is compared with the experimental value obtained by electron paramagnetic resonance (EPR). The local structure distortion is considered to obtain the crystal field parameters. The theoretical study gives the ZFS parameter D similar to that from experiment. However, calculation considering small distortion in local structure around Cr(3+) gives better agreement with the experimental value of ZFS parameter.

EPR, optical absorption and superposition model studies of Cr3+ doped dipotassium stannic chloride monohydrate

Electron paramagnetic resonance (EPR) study of Cr 3+ doped cesium tetrabromozincate (CTBZ) single crystal is done at room temperature. The hyperfine structure for Cr 53 isotope is also obtained. Two magnetically inequivalent sites for Cr 3+ are observed. The spin Hamiltonian parameters are evaluated as: D = 234×10 -4 cm -1 , E = 69×10 -4 cm- 1 , g = 2.0104, A = 80×10 -4 cm -1 for site I and D = 235×10 -4 cm -1 , E = 70×10 -4 cm -1 , g = 2.0061, A = 82×10 -4 cm -1 for site II, respectively. The optical absorption spectra are recorded at room temperature. The energy values of different orbital levels are determined. The values of various parameters obtained are: B = 602 cm -1 , C = 2504 cm -1 , Dq = 1870 cm -1 , h = 1.63 and k = 0.21, where B and C are Racah parameters, Dq is crystal field parameter, and h and k are nephelauxetic parameters, respectively. Theoretical zero-field splitting (ZFS) parameters for Cr 3+ at two sites in CTBZ are evaluated using superposition model and microscopic spin Hamiltonian theory. The theoretical ZFS parameters are in good agreement with the experimental values.