Optical Properties of Potassium Europium Tungstate Phosphors

The optical properties and quantum efficiency of potential red K 5 Eu x (WO 4 ) 2.5+1.5x (x = 0.5-3.0) phosphors for a novel phosphor liquid crystal display (LCD) are measured under near-UV excitation (394 nm). The quantum efficiency of K 5 Eu 2.0 (WO 4 ) 5.5 phosphor fired at 900°C for 3 h is 0.46 at 365 nm and 0.54 at 394 nm. The optical and morphological suitability of K 5 Eu x (WO 4 ) 2.5+1 5x phosphors is discussed for their application in phosphor LCDs. The emission peak of K 5 Eu 2.0 (WO 4 ) 5.5 phosphor is located at 615 nm and the Commission International del'Eclairage (CIE) coordinates are x = 0.63, y = 0.33.