Microstructural analysis, dielectric properties and room temperature magnetic ordering of Pr-doped ZnO nanoparticles

Abstract

Praseodymium (Pr ion)-doped zinc oxide nanoparticles (Zn1−xPrxO, x = 0.00, 0.02, 0.05) were prepared by chemical co-precipitation method. The as-dried samples were annealed at 400 °C for 6 h duration in vacuum (10−2 mm of Hg). Crystallographic phase formation of each prepared sample is determined by matching the peak positions of the observed X-ray diffractograms with those of JCPDS file no. 76-0206. Rietveld refinement of the XRD data is also carried out to confirm the desired crystallographic phase. Analysis of FTIR spectroscopic data confirms that no unwanted chemical bonding related to impurity is present in the sample. Intrinsic defects are investigated by observing photoluminescence spectroscopy of each sample. Due to the presence of bound magnetic polaron interaction mediated by defects like oxygen vacancy and zinc vacancy, both 2 and 5% Pr-doped ZnO nanoparticles show unsaturated hysteretic magnetization versus magnetic field loop at room temperature along with the presence of paramagnetic contribution. The presence of paramagnetic and ferromagnetic contribution confirmed from the nature of variation of magnetization vs. temperature curves. Dielectric measurements of each sample show that the substitution of dopant enhances the dielectric constant of the host system of ZnO and reduces the dielectric loss. AC electrical conductivity of the doped sample is lowered compared to that of ZnO which indicates that the doped samples would be useful for dielectric applications. The improved magnetic and dielectric properties of the doped samples open a new area for application in spintronic device as dilute magnetic dielectric.