Enhanced luminescence of GdTaO4:Eu thin-film phosphors by K doping

The effect of K⁺ ions on GdTaO₄:Eu³⁺ thin-film phosphors was investigated in order to improve their luminescent properties. The GdTaO₄:Eu_0.1, K_x thin films were synthesized by sol-gel process, and characterized through measuring their microstructure and luminescence. The results indicated that photoluminescence (PL) intensity of GdTaO₄:Eu³⁺ film was improved remarkably by K doping. There were two maxima in the curve of PL intensity against K⁺ dopant concentration, where one was improved up to 2.1 times at x = 0.001 and the other was enhanced up to 2.7 times at x = 0.05. The first maximum was regarded as the alteration of the local environment surrounding the Eu³⁺ activator by incorporation of K⁺ ions, and the second maximum was due to the flux effect. Additionally, the luminescence increased with the increase of firing temperature from 800 °C to 1200 °C.