Effect of Annealing on the Structural and Magnetic Properties of 3% Sm Doped ZnO

Hanan Hassan Hantour

doi:10.11648/j.ijecec.20180401.12

Abstract

The present study focuses on the structural and magnetic properties of Sm doped ZnO at 3% concentrations. These compounds have been synthesized by a chemical coprecipitation method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and magnetization method (M– H). The XRD pattern of all the samples showed ZnO hexagonal wurtzite structure with sharp and intense peaks with small change in lattice parameters due to Sm doping in ZnO, indicating the substitution of Sm ion for Zn sites. Magnetic measurements show an enhancement in room temperature ferromagnetism (RTFM) with Sm doping. Ferromagnetic behavior exists over and above the diamagnetic behavior, RTFM related to The Zn vacancies and diamagnetic (which exists over alarge scale) related to the oxygen vacancies which mediate the interaction of dopant ions.

Highlights

ZnO due to its wide direct band-gap (3.37 eV), large exciton energy (60 meV), chemical and thermal stability as well as low toxicity is considered to have important properties in basic and applied researches [1,2,3,4,5]
Samples of ZnO and ZnO:Sm doped have been prepared by chemical coprecipitation by mixing an appropriate amount of NaOH, ZnCl2 and SmCl2 prepare ZnO nanoparticle, 0.5M aqueous solution of ZnCl2 and 1M of NaOH were prepared in deionized water
Sharp and intense peaks corresponding to the hexagonal wurtzite structure of ZnO with P63mc as space group were observed

Summary

Introduction

ZnO due to its wide direct band-gap (3.37 eV), large exciton energy (60 meV), chemical and thermal stability as well as low toxicity is considered to have important properties in basic and applied researches [1,2,3,4,5]. Doping of ZnO allows it’s optical and magnetic properties to be adapted, through alteration of its electronic structure and band gap [11]. Optical excitation will induce electron–hole pairs where the excitons will form just below the conduction band. These excitons are sensitive to physical and chemical environment in ZnO structure as well as to the presence of defects and dopant. Theoretical investigations revealed stable FM coupling between RE ions are mediated by the delocalized electrons. This is beneficial to ZnO, since it exhibits n-type conductivity with a large population of‘s’ electrons [17]. Few reports are available on RE doped ZnO nanoparticles which provide information about the density of RE ions and the response of the nanoparticles to the applied magnetic field

Experimental

Structure and Microstructure Analysis

VSM Characteristic Figure 7 shows dc magnetization hysteresis loop of pure