A combination of thin-film deposition and physical masking steps were used to generate libraries of the rare earth activated refractory metal oxides,Gd(La,Sr)AlOx.Systematic variation of composition and processing conditions afforded tricolor phosphors with the following nominal compositions,(Gd0.46Sr0.31)Al1.23OxF1.38:Eu0.062+(green),La0.5Al1.5Ox:Eu0.042+(blue), andGd0.77Al1.23Ox:Eu0.063+(red), which had quantum efficiencies of ⩾94&percent;, ≃60&percent;, and ⩾93&percent;, respectively at&lgr;maxex.The high quenching temperatures (250–350 °C), good chromaticities and refractory nature of these phosphors are desirable features for display applications. ©1997 American Institute of Physics.