Eu3+ luminescence in La5Si2BO13 with apatite related structure and magnetic studies in Ln5Si2BO13 (Ln=Gd, Dy)

Eu3+ photoluminescence is studied in La5Si2BO13 with apatite related structure. La5−xEuxSi2BO13 [x=0.05, 0.1, 0.3, 0.5, 0.7, 1.0, 2.0] compositions are synthesized. The emission results shows that Eu3+ ions occupy two different cationic sites viz., La(1) and La(2). The increase in the intensity of 5D0–7F0 line with increasing Eu3+ content shows the preferential occupancy of Eu3+ in La(2) site due to the existence of short La(2)–O(4) (free oxide ion) bond. The observation of antiferromagnetic interactions in Gd and Dy analogues supports the structural features elucidates from photoluminescence studies.