The wavelength-modulated spectrum of SrTiO₃ and KTaO₃

It is shown experimentally that the temperature variation of the band gap of SrTiO3 is determined by the phonon population rather than by the structural phase transition. Despite the great similarity between SrTiO3 and KTaO3 no similar temperature variation of the band gap is found in the latter material. © 1973.