Luminescence of isoelectronic impurities and antisite defects in garnets

Luminescence centres formation due to the doped isoelectron impurities (II) and antisite defects in the garnets of A3B5O12 (A=Y,Lu,Gd; B=Al,Ga) formula is considered. Substitution of the Y- or Lu-cations by La3+ and Sc3+ II in dodecahedral {c}-sites and of the Al-cations by Y3+,Lu3+,Sc3+II in octahedral (a)-sites of garnet lattice results in formation of new emission centers in the UV region. The factors that determine a capability of the II to form the luminescence centers are studied. These factors include the possibility of the II to occupy (a)- and {c}-positions in the garnet lattice, the difference in the ionic radii of II and regular cations (which has to be >0.12 A) and the differences in their electron structure. The most effective garnet phosphors are shown to be Y3Al5O12 and Lu3Al5O12 doped with the La3+ and Sc3+ II. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)