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

The optical transmittance and reflectance spectra of samarium doped bismuth–zinc–niobium-oxide (BZN) pyrochlore ceramics are investigated in the wavelength range of 200–1050 nm (200–1500 THz). 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 3.05 eV. In addition, above 350 THz, 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 200–1500 THz reflected a sharp decrease in the dielectric constant with increasing frequency down to 358 THz. 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 870 nm IR lasers that are used in optical communications. The calculated oscillator (Eo) and dispersion (Ed) energies near that critical range (375–425 THz) reflected an increase in both Eo and Ed with increasing Sm content.