Structural, microstructural, optical, and dielectric properties of Mn2+: Willemite Zn2SiO4 nanocomposites obtained by a sol-gel method

Abstract

The synthesis of Zn2SiO4 doped with Mn2+ ions at different concentrations have been successfully achieved by a conventional sol–gel method. The structure and morphology of the obtained samples were characterized by XRD, FTIR, Raman spectroscopy, EDAX, and FE-SEM, TEM. The XRD results of Zn2SiO4 samples with different Mn concentrations showed no obvious differences from the willemite structure. The SEM and TEM results showed the ceramic powders are nanometer sized spherical grains spherical forms and EDAX results confirmed the successful doping of Mn2+ ions into Zn2SiO4 matrix. The optical and dielectric properties of Mn2+ ions doped Zn2SiO4 show an appreciable difference between the levels of Mn2+ doping. The luminescence spectra showed that 0.25mol% Mn2+ in Zn2SiO4 gives a maximum intensity a in the green emission corresponding to the 4T1 (4G) → 6A1(6S) transition for tetrahedral-coordinated Mn2+ (weak crystal field) and at higher levels of Mn2+ doping the green band intensity decreases. The 0.25mol% Mn2+ in Zn2SiO4 also gives the highest ionic conductivity at 373 K. The dielectric constant (ε′), loss tangent (tan δ) and AC conductivity (σac) properties as the function of frequency have also been analyzed and those are strongly dependent on Mn ion concentrations.