Luminescent Properties of Eu3+-Doped Ba2Bi2/3TeO6 and BaBiNaTeO6 Double Perovskite as New Orange-Red Emitting Phosphors

Novel orange-red phosphors based on Eu3+-activated Ba2Bi2/3TeO6 and BaBiNaTeO6 double perovskite were synthesized both by using a solid state reaction method and by using a Na2Sx (x = 2-6) flux. Both Ba2Bi2/3TeO6 (A(2)BB'O-6) and BaBiNaTeO6 (AA'BB'O-6) have a cubic structure with rock-salt ordering of the B-site cations, with space group Fm3m and lattice parameters of 8.4719 angstrom and 8.3221 angstrom respectively. The structures of the two double perovskites differ from each other in the local coordination of Bi3+ that is substituted by the Eu3+ activators. The use of Na2Sx flux for the preparation of Ba2Bi2/3TeO6:Eu3+ and BaBiNaTeO6:Eu3+ results in the incorporation of the Na+ ion into and the extraction of the Ba2+ ion from the lattice, and this, in turn, leads to a decrease in the lattice parameters. The luminescence intensity significantly increases with the lattice distortion/disorder caused by the Ba2+ ion vacancy and the incorporation of Na+ in the lattice. The relative intensity of red (615 nm; D-5(o)-F-7(2)) to yellow (592 nm; D-5(o)-F-7(1)) in the luminescence spectra of Ba2Bi2/3TeO6:Eu3+ increases as a result of the disappearance of the centrosymmetric nature of the Eu3+ crystallographic site. (C) 2011 The Electrochemical Society. [DOI: 10.1149/2.046203jes] All rights reserved.