Luminescence of Ce3+ ions in alkaline earth borophosphates

The luminescent properties of Ce3+ ions in alkaline earth borophosphates MBPO5 (M = Sr, Ba) were studied upon excitation in the 3.5-15 eV region. In MBPO5 (M = Sr, Ba; x ≤ 0.01) solid solutions two principal Ce3+ centers are observed. The dominant center was found to be produced by the direct substitution of the dopant ion for M2+ without a local charge compensation. The other center is ascribed to an associate of a Ce3+ ion and a point defect. It was shown that the lowest 5d state of Ce3+ in MBPO5 is at relatively high energy due to the high degree of ionicity of the MO bond. The influence of the structural features of MBPO5 on the luminescent behavior of Ce3+ is discussed.