Optical Absorption in Pure SrTiO3 and Nb Doped SrTiO3

SrTiO3 (STO) is of considerable interest because of very strong electron-phonon coupling. We measure the property electron-phonon coupling in order to elucidate the origin of the ferroelectricity from electronic structure. We measured the mid-infrared optical absorption of pure STO and Nb doped STO in order to investigate this electron-phonon coupling and multi-phonon. The mid-infrared absorption measurements were made over a wavenumber range from 400 to 7800 cm(-1), and over a temperature range from 30 to 150(30 . 40 . 50 ... 150). The Nb doped STO shows the broad infrared absorption peak near 2000 cm(-1).