Synthesis of NASICON Nanoparticles and Their Optical Properties

The nanocrystalline NASICON powders have been synthesized by sol–gel route and structural and optical properties have been investigated. The effect of increase in sintering temperature (800 to 1000 °C) on crystallite size and band gap has been investigated which shows increase in crystallite size, shift in the band gap towards higher energy from to 3.90 to 5.25 eV for direct transition and from 3.58 to 4.90 eV in indirect transition. The XRD results show the presence of impurity phases along with NASICON phase and compositional variation with temperature. TEM results confirm the variation in particle size. Single phase of NASICON nanopowders were prepared by varying sintering time. XRD, TEM and transmittance results showed presence of single phase and nanocrystalline nature of the particles. The shift in band gap from 4.91 to 5.25 eV for direct transition and 4.30 to 4.90 eV for indirect transition towards higher energy side with decrease in particle size can be attributed to size effect. Results indicate that structural and optical properties can be easily modulated significantly by altering particle size and sintering temperature during synthesis.