Theoretical studies on the electron paramagnetic resonance parameters for the tetragonal VO2+ center in CaO-Al2O3-SiO2 system

Abstract

In this work, thehighorderperturbationformulaeoftheelectronparamagneticresonance (EPR) parameters, g \& A for a VO$^{2+}$3d$^1$ ion in tetragonal symmetry (compressedoctahedron) are adopted to theoreticallystudytheseparametersofthe tetragonal VO$^{2+}$ center in CaO-Al$_2$O$_3$-SiO$_2$ system. Becausethespin-orbit (SO) couplingparameter$\zeta_p$ ($\approx$151 cm$^{-1}$) ofligand O$^{2-}$ is close to that ($\approx$248 cm$^{-1}$) ofthe central V$^{4+}$ ion in thecluster [VO$_6$]$^{8-}$withstrongcovalence, theeffectofthe SO couplingparameter$\zeta_p$onEPRparameters are consideredonthebasisofclusterapproach. TheobtainedEPRparameters show goodagreementwiththe experimental values and needfeweradjustableparametersthanpreviousstudies. Andthe local structureofthe tetragonal VO$^{2+}$ center in CaO-Al$_2$O$_3$-SiO$_2$ system due to Jahn-Tellereffect is obtained from theanalysisoftheEPRparameters. Theresults are discussed.