Temperature-dependent dielectric and magnetic properties of Mn doped zinc oxide nanoparticles

Mn substituted zinc oxide (ZnO) nanoparticles with general formula Zn1-xMnxO (x=0.0, 0.03, 0.05 and 0.10) were synthesized through a sol-gel route. The result of x-ray diffraction (XRD) analysis confirms the presence of wurtzite crystal structure for all samples suggested that doped Mn ions are occupying regular Zn sites. Transmission electron microscopy (TEM) images exhibit the growth of particle size in the range of 30-50 nm. The results of dielectric measurement indicate that the parameters epsilon', epsilon '', tan delta and sigma(ac) are decreasing with the increase in frequency; whereas these parameters increase with the increase in temperature. Dielectric parameters are also found to increase with the increase in Mn concentration up to 5%, beyond this value the parameters become lower. The dielectric properties have been explained on the basis of space charge polarization according to Maxwell and Wagner's two-layer model and the hopping between adjacent Mn2+ and Mn3+ ions. The analysis of temperature dependant magnetization data gives the idea about ferromagnetic (FM) exchange interaction. (C) 2014 Elsevier Ltd. All rights reserved.