ESR study on Cr3+ and Mn2+ doped ZnAl2S4 single crystal

Abstract

The spinel ZnAl2S4 compound has been studied by electron spin resonance (ESR) technique. Paramagnetic Cr3+ and Mn2+ ions have been substituted for Al3+ and Zn2+ ions to investigate crystalline field symmetry and electronic structure as a function of the temperature between 10 and 300 K. Computer analysis of the ESR data indicated a high homogeneity and quality for the crystal. The magnetic electrons of Cr3+ ion are highly localized (98.6%) on Cr3+ while the unpaired electrons of Mn2+ are significantly delocalized (about 20%) to get covalent bonding with neighboring atoms (possibly Zn, S, Al). The ZnAl2S4 crystal is shown to be in the normal spinel structure without any significant distortion detectable even by a very high sensitive technique like ESR. The temperature does not affect these localization properties of the electrons either, indicating strong stability of the crystal symmetry. (C) 2002 Elsevier Science B.V. All rights reserved.