Structural and optical characterization of Mg2SiO4 and Mg2SiO4-Pr6O11 nanocomposite for optical devices

Abstract

The knowledge on optical properties of magnesium orthosilicate (Mg2SiO4) and its composite materials are very important as these silicate-based materials play a significant role in the field of optics and electronics. Mg2SiO4 nanomaterial and Mg2SiO4-Pr6O11 nanocomposite materials were therefore chosen in the present study, and they were synthesized in the present work, by simple sol-gel route. Powder x-ray diffraction (PXRD) pattern, Fourier-transform infrared (FT-IR) spectroscopy and ultraviolet–visible (UV–vis) spectroscopy techniques were adopted to understand the structural and optical properties of the prepared samples. The crystalline size of the two samples were estimated using Debye–Scherrer's equation and they are found to be 43 nm (Mg2SiO4) and 52 nm (Mg2SiO4-Pr6O11). The FT-IR results of Mg2SiO4-Pr6O11 revealed the SiO4 stretching and PrO vibrations clearly. The optical absorbances were used to determine the absorption coefficient α and hence the optical band gap energies Eg whose values are 5.60 eV and 5.17 eV for the samples Mg2SiO4 and Mg2SiO4-Pr6O11 respectively. Further with the help of UV–Vis spectra, the refractive index (n), extinction coefficient (k), optical conductivity (σ), real and imaginary part of dielectric constant (ε′ and ε''), volume energy loss function (VELF), surface energy loss function (SELF), linear susceptibility and non-linear susceptibility were investigated with respect to the incident photon energy. The Urbach energy was calculated using ln α vs graph and they are found to be 21 meV and 265 meV for Mg2SiO4 and Mg2SiO4-Pr6O11. The non-linear optical properties of the samples were also discussed by deriving the linear and non-linear optical susceptibilities and by exploring the possibilities of usage of this composite in optical devices.