Structure, optical and magnetic characterizations of Mn doped ZnS dilute magnetic semiconductor synthesized by mechanical alloying

Abstract

Pristine Mn doped ZnS (Zn1−xMnxS, x=0.03–0.1) dilute magnetic semiconductors (DMSs) have been synthesized for the first time by mechanical alloying the stoichiometric mixture of the elemental powders with different Mn concentrations at room temperature under inert atmosphere without any impurity or secondary phase formation. Successive presence of both major cubic and minor hexagonal phases in all the milled samples has been ascertained and transformation of hexagonal to cubic phase with increasing Mn concentrations has been established by Rietveld method of powder structure refinement. Different structural and microstructure parameters such as particle size and r.m.s. lattice strain have been measured. Distributions of particle sizes of both cubic and hexagonal phases indicate toward the monodispersity of the particles with increasing milling time. Presence of different kinds of stacking faults is evidenced in HRTEM images and qualitative measures of these faults are obtained from Rietveld analysis. Rietveld analysis confirms the partial substitution of Zn atoms by Mn atoms in the ZnS lattice. XPS analysis confirms the presence of multiple valence states of Mn atoms. The M-H measurement shows superparamagnetic behavior at low temperature (5K) and paramagnetic behavior at 300K. Optical band gap and photoluminescence properties of Zn1−xMnxS have also been determined and correlated with the microstructure parameters as revealed from Rietveld analysis.