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Published on: April 14, 2020
Crystal field effect on EPR and optical absorption properties of natural green zoisite
Henry Javier-Ccallata1, Shigueo Watanabe
1Departamento de Física Nuclear, Instituto de Física, Universidade de São Paulo, Rua do Matão, Travessa R, 187, CEP 05508-900, São Paulo, SP, Brazil. henrysjc@gmail.com
Abstract:
In this study the electron paramagnetic resonance (EPR) and optical absorption (OA) of natural crystal of zoisite were investigated after γ ((60)Co) irradiation and high temperature annealing. EPR measurements show that the zoisite from Tefilo Otoni MG Brazil contain Cr(3+), Fe(3+) and Mn(2+) ions and occupy distorted Al(3+) octahedral and tetrahedral sites which are subjected to the action of a strong crystal field in axial direction. Absorption bands which in principle give rise to sets of EPR lines between 500 and 2500 G were found using the deconvolution method. The application of high doses of gamma ray and high temperature annealing has shown no significant effects on EPR and OA spectra. Spin-allowed, spin-forbidden and crystal field parameters were calculated for 3d(3) configuration and interpreted using the spin Hamiltonian formalism containing axial and rhombic terms in low symmetries.
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