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Eu 3+ luminescence: A spectral probe in M 5 (PO 4 ) 3 X apatites (M=Ca or Sr; X=F - , Cl - , Br - or OH - )

1995; IOP Publishing; Volume: 7; Issue: 44 Linguagem: Inglês

10.1088/0953-8984/7/44/014

1361-648X

R. Jagannathan, M. Kottaisamy,

Lanthanide and Transition Metal Complexes

Eu3+ luminescence is of special importance as a spectral probe apart from its application in phosphor materials. This is possible for the reason that Eu3+ has several structure-dependent transitions enabling one to gain insight about the site that it occupies in a given host. On this basis we have attempted to explore the different cationic sites present in the apatite system. In fluoroapatites, Eu3+ predominantly occupies MII sites, with the local symmetry becoming enhanced from C1h to a tetragonal symmetry attributed to charge-compensating species. In addition to both kinds of site of the apatite system (MI and MII) occupied by Eu3+, we have observed the presence of a third kind of Eu3+ site. The observation of unusually strong 5D0 to 7F0 emission of Eu3+ in fluoroapatites and bromoapatites has been explained. Also various results on the luminescence features of Eu3+ correlated with the structural details known are discussed.