Near infra-red luminescence of BaTiO3: Cr

AbstractIt was found that Cr in BaTiO3crystals reveals a characteristic luminescence with four sharp emission lines at 781.6 (A1), 776.4 (A2), 768.8 (A2), 766.8 (A3) and 766.8 nm (A4) for 74 K. Considering EPR data, temperature- and lifetime behaviour, the A3and A4lines are interpreted to be R1,2-lines originating from zero-phonon 2E→ 4A2transitions of octahedral Cr3+replacing Ti4+. The A1,2emission lines may originate from Cr3+exchange coupled with an unknown compensating defect. It is remarkable that the inhomogeniously broadened A-lines are well described by Lorentz curves at low temperatures, with half-width (FWHM about 10 cm−1) depending hardly on the temperature.