Photoluminescence properties of Sm2-doped BaBr2 under hydrostatic pressure

Photoluminescence spectra of Sm2-doped BaBr2 have been measured under hydrostatic pressures up to 17 GPa at room temperature. In the low pressure range a red-shift of the broad 5d4f transition of -145 cm -1/GPa is observed. From 5 to 8 GPa a phase mixture of the initial orthorhombic phase and the high-pressure monoclinic phase gives rise to two 5d4f bands, which are strongly overlapping. Above 8 GPa the crystal is completely transformed to its high-pressure phase where two different Sm2 sites exist, but only one broad 5d4f transition is detected. It exhibits a red-shift of -36 cm-1/GPa. In addition, the line shifts of the 5D07FJ (J=0, 1, 2) transitions are investigated. Linear shifts of -19 cm-1/GPa for J=0, 2 and of -13 cm-1/GPa for J=1 are observed in the pressure range from 0 to 5 GPa.