Luminescence of BaBr2:Eu2+ under hydrostatic pressure

Luminescence spectra of BaBr2:Eu2+ have been measured under pressures up to 27 GPa at room temperature. In the low-pressure range a red-shift of the 5d–4f transition of −225 cm−1/GPa is observed. From 3 to 10 GPa a phase mixture of the original orthorhombic phase and the high-pressure monoclinic phase gives rise to two luminescence bands. Above 10 GPa the crystal is completely transformed to its high-pressure phase where two different Eu2+ sites exist of which, however, only one 5d–4f transition is detected. This transition exhibits a red-shift of −200 cm−1/GPa. The shifts are compared with other literature data.