Photoluminescence Spectra and Unusual Temperature Shift of Zero-Phonon Emission Line of V3+ in SrTiO3

The paper presents the first observation of photoluminescence spectra of V3+ impurity in SrTiO3. The broad band of the observed emission is located in the near IR region and at low temperatures consists of a pronounced zero-phonon line (ZPL) with a maximum at 1157.1 nm (8642 cm(-1)) at 77 K and developed vibronic sidebands extending to 1450nm. The observed ZPL is associated with an intracenter T-1(2g) -> T-3(1g) or a closely located E-1(g) -> T-3(1g) emission transition in V3+ (3d(2)) ions replacing Ti(4+ )ions. It was found that the temperature shift of zero-phonon line is unusually large and its frequency decreases upon lowering the temperature. The local configuration instability of V3+ ions in the (3)T(1g )ground state caused by soft TO1 temperature-dependent phonon mode present in SrTiO3 is considered as a possible source of the observed unusual temperature shift.