Theoretical calculations of spin-Hamiltonian parameters for CsCdX(3):Ni(2+) (X=Cl, Br) crystals from the two-mechanism model.
The high-order perturbation formulas of spin-Hamiltonian (SH) parameters (g factors g( parallel), g( perpendicular) and zero-field splitting D) for 3d(8) ions in trigonal octahedral sites of crystals are derived considering not only the crystal-field (CF) mechanism, but also the charge-transfer (CT) mechanism (which is neglected in the extensively used CF theory). From these formulas and by considering the suitable impurity-induced local lattice relaxation, the SH parameters of CsCdX(3):Ni(2+) (X=Cl, Br) crystals are calculated. The results are in reasonable agreement with the experimental values. The sign of Q(CT) (Q=Deltag( parallel), Deltag( perpendicular) or D, where the g-shift Deltag(i)=g(i)-g(e), g(e) approximately 2.0023 is the free-electron value) due to CT mechanism is the same as that of the corresponding Q(CF) due to CF mechanism. The relative importance of CT mechanism (characterized by Q(CT)/Q(CF)) increases with the increasing atomic number of ligand X. So, for 3d(n) ion clusters in crystals with heavy element ligand ion (e.g., Br(-)), the reasonable explanations of SH parameters should contain the contributions from both CF and CT mechanisms.
Wang
Fang
F
Department of Material Science, Sichuan University, Chengdu 610064, People's Republic of China.
Xiao-Xuan
Wu
W
Wen-Chen
Zheng
Z
D001965:Bromides / Q000737:chemistry; D002104:Cadmium / Q000737:chemistry*; D002586:Cesium / Q000737:chemistry*; D002712:Chlorides / Q000737:chemistry; D003460:Crystallization; D004578:Electron Spin Resonance Spectroscopy; D008956:Models, Chemical; D009532:Nickel / Q000737:chemistry*; D013113:Spin Labels
D001965:Bromides; D002712:Chlorides; D013113:Spin Labels; D002104:Cadmium; D002586:Cesium; D009532:Nickel