Raman and fluorescence spectra of ferroelectric microregions in KTaO3

Abstract

The Raman and near-infrared fluorescence spectra of pure and ultra-pure samples are compared to the spectra of a reduced ultra-pure KTaO₃ sample where oxygen vacancies have been created. The luminescence of the reduced sample in the neighborhood of 14570 cm⁻¹ is enhanced and the Raman peaks associated with ferroelectric microregions become more pronounced. We conclude that the oxygen vacancies are thus at the origin of the ferroelectric microregions observed in pure and doped KTaO₃ materials.