Microstructure, optical, dielectric and electrical characterizations of Mn doped ZnO nanocrystals synthesized by mechanical alloying

Mn doped ZnO nanocrystals are successfully synthesized, for the first time, by mechanical alloying the stoichiometric mixture of pure ZnO and Mn powders. The structural and compositional analyses are carried out using X-ray diffraction (XRD) and high resolution transmission electron microscopy (HRTEM). Rietveld's analysis of the XRD patterns confirms the formation of single phase wurtzite Zn0.90Mn0.10O nanostructures. Different structural and microstructural parameters such as lattice parameters, crystallite size, r.m.s. strain, stacking faults etc. have been ascertained from the Rietveld analysis. UV-vis spectra are analyzed for band gap measurement and photoluminescence (PL) emission spectra have also been analyzed for estimating different structural defects and optical features of the samples. Temperature dependent dc electrical behavior is studied and the conduction mechanism has been explained by the Godet variable range hopping theory (3D G-VRH). Complex impedance analysis is used to distinguish the grain and grain boundary contribution to the system and it suggests the dominance of grain resistance in the synthesized samples. The dielectric behavior, electric modulus and ac conductivity are studied as a function of temperature (573-773 K) and frequency (100 Hz to 3 MHz). The optical and electrical characterizations predict that the synthesized materials have potential for use in optoelectronics applications.