Tailoring the optical phonon modes and dielectric properties of nanocrystalline SrTiO<inf>3</inf> via Yb doping

We report the effect of Yb doping on the optical phonon modes and dielectric properties of nanocrystalline SrTiO3. Undoped and Yb doped SrTiO3 samples are processed by solid-state synthesis route. It is observed that all the samples are of perovskite phase and nanocrystalline nature. Softening of the oxygen defects induced optical phonon modes is observed in Yb doped SrTiO3. Lattice distortion increases with increase of Yb. Increase of dielectric permittivity and dielectric loss in Yb doped SrTiO3 proves the improvement of energy dissipation in SrTiO3 through Yb doping. Dielectric relaxation of the undoped SrTiO3 is mostly due to the hopping of localized charge carriers where as non-dispersive transport of localized carriers and clustering of oxygen vacancies is observed in Yb doped SrTiO3. There is a drastic increase (∼102) of the ac conductivity in Yb doped SrTiO3. We elaborately discuss the impact of optical phonon modes and dielectric properties of Yb doped SrTiO3.