SYNTHESIS AND STUDY OF OPTICAL AND MAGNETIC PROPERTIES OF NANOCRYSTALLINE Zni _.Mn ,0

Abstract

Mn doped ZnO nanocrystalline samples have been synthesized using a simple autocombustion method. The as-synthesized Mn doped ZnO nanocrystals were characterized by X-ray diffraction and scanning electron microscopy. An increase in the hexagonal lattice parameters of ZnO is observed on increasing the Mn concentration. Optical absorption studies show an increment in the band gap with increasing Mn content, and also give evidence for the presence of Mn2+ ions in tetrahedral sites. All Znf-,MnO (0 <x < 0.20) samples are paramagnetic at room temperature as find by SQUID measurements even we find room temperature ferromagnetism for low doped Mn-ZnO. However, a large increase in the magnetization is observed below 50 K. This behavior, along with the negative value of the Weiss constant obtained from the linear fit to the susceptibility data below room temperature, indicate ferrimagnetic behavior. The origin of ferrimagnetism is likely to be either the intrinsic characteristics of the Mn doped samples, or due to some spinel-type impurity phases present in the samples that could not be detected.