Studies of structural, electrical and optical properties of MgNb2O6-Mg4Nb2O9 nanocomposite for possible opto-electronic applications

Abstract MgNb2O6 (MN2)-Mg4Nb2O9 (M4N2) nanocomposite was successfully synthesized by a two-stage process at 1100 °C. The prepared nanocomposite was characterized by XRD, Raman spectroscopy, EDX, FESEM and HRTEM. Band gap, photoluminescence and dielectric behaviour were also studied. XRD confirmed orthorhombic and hexagonal crystal structure of MN2 and M4N2 phase, respectively. The crystallite size of MN2 and M4N2 was found equal to 43.52 and 41.38 nm, approximately. Raman spectroscopy and EDX analysis were performed to investigate molecular bonds and elemental composition, respectively. HRTEM confirmed nanoparticles of average size 44 nm. Clear lattice image and prominent spots in SAED pattern confirmed the crystallinity of prepared material. Grain size was estimated between 0.77 and 1.12 µm by FESEM analysis. A high bandgap (Eg) was found equal to 3.44 eV from diffuse reflectance spectroscopy. Photoluminescence spectroscopy revealed emission near 391.4 nm which was basically a prominent violet emission. Dielectric constant of prepared ceramics was measured 9.8 at 110 MHz and low dielectric loss was also observed. Excellent optical and dielectric properties may contribute towards certain opto-electronic applications.