Hiroki Banno

Syntheses and Luminescence Enhancement of Li1+x(Ta1-zNbz)1-xTixO3:RE3+ (RE=Eu, Er, Tm or Dy) Phosphors

We synthesized the phosphors of RE3+-doped Li1+x (Ta1-zNbz)1-xTixO3 (LTNT) with various emission colors by solid-state reaction in air using a conventional electric furnace, where RE=Eu, Er, Tm, or Dy. The optimal host composition with each dopant was determined for the highest photoluminescence (PL) intensity; the relevant chemical formulas were Li1.11Ta0.89Ti0.11O3 (x=0.11 and z=0) with Eu3+, Li1.03 (Ta0.2Nb0.8)0.97Ti0.03O3 (x=0.03 and z=0.8) with Er3+, Li1.08 (Ta0.4Nb0.6)0.92Ti0.08O3 (x=0.08 and z=0.6) with Tm3+, and Li1.14 (Ta0.6Nb0.4)0.86Ti0.14O3 (x=0.14 and z=0.4) with Dy3+. The crystal structures of the phosphors were refined by the XRD-Rietveld method to clarify the relationship between the PL properties and crystal structures. In the LTNT host material, the most effective activator was the Eu3+ ion, with an internal quantum efficiency of 97%. The efficient PL emission is closely related to the coordination environment of Eu3+ in the [Li (Eu) O12] polyhedron of the host LTNT.