Optical and dielectric properties of nano BaNbO3 prepared by a combustion technique

Nanocrystalline Barium niobate (BaNbO3) has been synthesized by a novel auto-igniting combustion technique. The X-Ray diffraction studies reveals that BaNbO3 posses a cubic structure with lattice constant a = 4.071 A. Phase purity and structure of the nano powder are further examined using Fourier-Transform Infrared and Raman spectroscopy. The average particle size of the as prepared nano particles from the Transmission Electron Microscopy is 20 nm. The UV-Vis absorption spectra of the samples are recorded and the calculated average optical band gap is 3.74eV. The sample is sintered at an optimized temperature of 1425OC for 2h and attained nearly 98% of the theoretical density. The morphology of the sintered pellet is studied with Scanning Electron Microscopy. The dielectric constant and loss factor of a well-sintered BaNbO3 at 5MHz sample is found to be 32.92 and 8.09 x 10-4 respectively, at room temperature. The temperature coefficient of dielectric constant was−179pp/oC. The high dielectric constant, low loss and negative temperature coefficient of dielectric constant was−179pp/oC. The high dielectric constant, low loss and negative temperature coefficient of dielectric constant makes it a potential candidate for temperature sensitive dielectric applications.