Near UV-pumped yellow-emitting Ca₃TeO₆:Dy³⁺ phosphor for white light-emitting diodes

A series of Ca₃TeO₆:xDy³⁺ (x = 0.01, 0.02, 0.05, 0.10, 0.15, 0.20, and 0.25) tellurate yellow-emitting phosphors were synthesized via the high-temperature solid-state method. The X-ray diffraction patterns of these phosphors revealed that all the samples have a double-perovskite type with monoclinic structure. The Ca₃TeO₆:Dy³⁺ phosphor exhibit characteristic emission transitions, ⁴F_9/2-⁶H_15/2 transition and ⁴F_9/2-⁶H_13/2 transition, respectively. The intense yellow light indicates that Dy³⁺ ion occupies the interstitial Ca site in the Ca₃TeO₆ host. The optimal Dy³⁺ ion concentration was determined as 10 mol%. The critical energy transfer distance was calculated as 14 Å. The concentration quenching mechanism of Dy³⁺ was investigated in details. The temperature effect on photoluminescence was discussed in order to evaluate the thermal stability. The obtained results illustrate Ca₃TeO₆:Dy³⁺ was a new kind of yellow-emitting potential phosphor for WLEDs.