Refluxing synthesis of Mn-doped ZnO nanoparticles and their applications in dielectric ceramics

Abstract

Pure and manganese (Mn)-doped zinc oxide (ZnO) (0, 1, 2 and 4 wt%) nanoparticles are synthesised by refluxing method. The as-synthesised nanoparticles are characterised by X-ray powder diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy and energy-dispersive X-ray spectroscopy (EDS). The results show that pure and Mn-doped ZnO nanoparticles have a hexagonal wurtzite structure and the (101) diffraction peaks position of Mn-doped ZnO shift toward the smaller value of diffraction angle compared with pure ZnO powders, confirming that the Mn 2+ were well incorporated into ZnO crystal lattice. Moreover, Mn doping also restrained the growth of particles and the size decreased from 14.9244 to 13.1196 nm with the increase in doping concentration from 0 to 4 wt%. The EDS analysis for 2 wt% Mn-doped ZnO confirms the presence of Mn in ZnO nanocrystal. The dielectric measurements show that Mn-doped ZnO ceramics exhibit higher dielectric constant, while dielectric constant and dielectric loss increased continuously with the temperature increased. In addition, 2 wt% Mn-doped ZnO ceramics showed the high dielectric constant (23 × 10 3 ) and low dielectric loss (0.95) at 125°C after sintering at 1000°C for 2 h.