Dielectric dispersion and energy band gap of Bi1.5−xSmxZn0.92Nb1.5O6.92 solid solution

Abstract

The optical transmittance and reflectance spectra of samarium doped bismuth–zinc–niobium-oxide (BZN) pyrochlore ceramics are investigated in the wavelength range of 200–1050nm (200–1500THz). The Sm content in the Bi1.5−xSmxZn0.92Nb1.5O6.92 solid solution significantly alters the optical properties. Therefore, increasing the Sm doping ratio from x=0.10 to x=0.13 decreased the indirect forbidden energy band gap from 3.60 to 3.05eV. In addition, above 350THz, increasing the Sm content decreases the dielectric constant values and alters the dielectric dispersion parameters. The dielectric spectra which were evaluated in the frequency range of 200–1500THz reflected a sharp decrease in the dielectric constant with increasing frequency down to 358THz. The spectra reflected a resonance peak at this frequency. Such resonance spectrum is promising for technological applications as it is close to the illumination of 870nm IR lasers that are used in optical communications. The calculated oscillator (Eo) and dispersion (Ed) energies near that critical range (375–425THz) reflected an increase in both Eo and Ed with increasing Sm content.