Structural, spectral, magnetic and thermal properties of VO2+ doped ZnS nanocrystals by co-precipitation method

Abstract

In the present work, VO2+ doped ZnS nanocrystals have been synthesized by simple co-precipitation method at room temperature. X-ray diffraction result reveals cubic structure of VO2+ doped ZnS nanocrystals. Micro-structural properties such as grain size, strain, dislocation density and texture coefficient are calculated. Both SEM and TEM images represent the non-uniformly distributed spherical like structures. Optical absorption spectrum vanadyl ions exhibits three characteristic peaks 516, 647 and 863 nm suggesting C4V symmetry and their evaluated crystal field and tetragonal field parameters are Dq = 1545 cm− 1, Ds = − 2215 cm− 1 and Dt = 987 cm− 1. From EPR spectrum the calculated spin Hamiltonian parameters are g║= 1.9423, g┴ = 1.980 and A║= 167 × 10− 4 cm− 1, A┴ = 62 × 10− 4 cm− 1. By correlating Optical and EPR studies confirm the tetragonally compressed octahedral site symmetry for VO2+ ions and the nature bonding between VO2+ and its ligands is covalent. The PL spectrum exhibits the violet, blue, green and strong orange emission bands and the corresponding CIE chromaticity coordinates are evaluated to be in white region. VO2+ doped ZnS nanocrystals showed the room temperature ferromagnetic property and their saturation, remnant magnetization values are 12.9 × 10− 3, 2.59 × 10− 3 emu/g respectively. TG-DTA curves indicate the thermal decomposition of the prepared sample at different temperatures and the corresponding total weight loss is 24.94%. The present results revealed that VO2+ doped ZnS nanocrystals may applications in white LED and spintronic devices.