Intrinsic luminescence from BaTiO₃crystals

Defect structure of semiconducting and insulating epitaxial oxides. Progress report, May 1, 1993--April 30, 1994

“…measurements of single crystal Fe:BaTiOa showed that Fe4+ yielded an absorption peak at 2.69 eV, which correlates well with the peak at E, +2.65eV in the BaTiO_ films [22]. Other optical absorption studies have shown Fe related defects with peaks at E,+2.34 and E,+2.48 eV [23]. We propose that the changes in the peak intensities for the mid-gap levels, after vacuum reduction may result from the reduction of Fe_+ to Fe4+.…”

Stabilization of small polarons in BaTiO3 by local distortions

“…Here we compare our calculations with experimentally observed green luminescences in BTO [7][8][9]. We estimated optical transition energies of defects involving electron small polarons at a fixed ground state atomic position based on the Franck-Condon principle [43].…”

“…Small polarons generally play important roles in electronic and ionic transport, optical properties, and charge compensations. In BTO, it has been experimentally reported that small polarons would be the origin of the green luminescence [7][8][9], mid-near-infrared absorption, and blue coloration [10][11][12][13][14]. Especially, the transport of charged carriers has been attributed to hopping of small polarons in some studies [15][16][17][18][19].…”

Effects of annealing temperature on the photoluminescence of RF sputtered Barium titanate thin films

“…In perovskite type crystals, at low temperature, a broad luminescence band is observed in the visible region due to the presence of defects or imperfections in the material [18]. In BT single crystal, a luminescent band centered at 500 nm is observed at low temperature range (18-300 K), when excited with an ultraviolet beam [19]. In particular, when pure BT sample is excited by radiation above its band gap, a broad luminescent band appears in the visible region whose energy is lower than the corresponding band gap energy [20,21].…”