Sol-gel synthesis and luminescent properties of M‧-type LuTaO4:Eu3+ phosphors

Eu³⁺ activated M‧-type LuTaO₄ phosphors were successfully prepared by using inorganic salts, citric acid and PEG400 via the Pechini sol-gel technique. Their crystallization, morphology, photoluminescence (PL) and X-ray excited luminescence (XEL) characteristics were investigated in detail. The results indicated that the M‧-type LuTaO₄ phase appeared at about 850°C, which was much lower than the crystallization temperature of the solid-state reaction. And the grain size of the phosphor was controlled from nano- to micron-scale by adjusting the sintering temperature. The optimal doping concentration of Lu_1-xEu_xTaO₄ phosphors was at x=0.10. With the sintering temperature increasing, PL intensity of the phosphor was improved remarkably, whereas its decay time was decreased. It is worth to notice that the sol-gel derived M‧-type LuTaO₄:Eu³⁺ phosphors reveal excellent XEL performance and easily controlled grain size, which implies that they will have promising applications in high-spatial-resolution X-ray imaging.