Luminescent properties of Eu, Tb or Bi activated yttrium germanates

Preliminary studies were conducted on Eu³⁺, Tb³⁺ or Bi³⁺ doped Y₂Ge₂O₇, Y₂GeO₅ and Y₄GeO₈ phosphors. Both photoluminescence and cathodoluminescent properties of the materials were measured. Among these materials, the luminescent intensities of Y₂Ge₂O₇:Eu, Y₂GeO₅:Tb and Y₂Ge₂O₇:Bi are relatively high and the luminescent colors of them are red, green and blue, respectively. In order to improve the luminescent properties for field emission display applications, further optimization is necessary. In addition, X-ray powder diffraction results indicate that Y₄GeO₈ phase forms in an orthorhombic unit cell, the parameters of which are: a=1.4976(5) nm, b=0.9357(6) nm, c=0.5885(3) nm, V_cell=0.82467(2) nm³.