Near infra-red luminescence of BaTiO3 : Cr

It was round that Cr in BaTiO3 crystals reveals a characteristic luminescen ce with four sharp emission lines at 781.6 (A(1)), 776.4 (A(2)), 768.8 (A(3 )) and 766.8 nm (A(4)) foT 74 K. Considering EPR data, temperature- and lif etime behaviour, the A(3) and A(4) lines are interpreted to be R-1,R-2-line s originating from zero-phonon E-2 --> (4)A(2) transitions of octahedral Cr 3+ replacing Ti4+. The A(1,2) emission lines may originate from Cr3+ exchan ge coupled with an unknown compensating defect. It is remarkable that the i nhomogeniously broadened A-lines are well described by Lorentz curves at lo w temperatures, with halfwidth (FWHM about 10 cm(-1)) depending hardly on t he temperature.