Variable temperature EPR spectra of Copper (II) ions in kainite crystals

Abstract

X-band electron paramagnetic resonance (EPR) studies on divalent copper ions embedded in KMgClSO 4·3H 2O single crystals have been performed at low temperature (123 K). The angular variation of the EPR spectra reveals the presence of two Cu 2+ sites, which have different orientations. The spin-Hamiltonian parameters of this six-coordinated cupric ion have been evaluated from the EPR spectra at 123 K. The forbidden lines due to Δ m I=±1 transitions are observed in between allowed transitions. The temperature variation EPR studies have also been performed both for a single crystal and a polycrystalline sample. The ground state wavefunction of Cu 2+ ions has been estimated and is found to be an admixture of d 3 z 2 − r 2 and d x 2 − y 2 . The temperature variation of the EPR spectra reveals that Cu 2+ ions exhibit dynamic Jahn–Teller effect. From the polycrystalline EPR data, the temperature dependent magnetic susceptibilities are evaluated and discussed.