Intense emissions in Ce3+/Eu2+ doped Ca5.93-mSrmBa(PO4)4O phosphors via host adjustment and energy transfer

Abstract

A series of Ca5.93-m-x-2ySrmBa(PO4)4O:xEu2+,yCe3+,yLi+ (0 ≤ m ≤ 0.5, 0 ≤ x ≤ 0.07, 0 ≤ y ≤ 0.05) phosphors were designed via solid-state reaction method, and the photoluminescence properties were studied for application in white light-emitting diodes (LEDs). When a small amount of Sr2+ was introduced into the initial Ca6Ba(PO4)4O host, the solid solution was formed, which was verified by the XRD technique. The Eu2+ in the host shows intense yellow emitting light, which can be largely enhanced by incorporating Sr2+ in the host. When the Ce3+ was doped into the host, blue emission was received under 380 nm excitation, and the optimal Ce3+ concentration is for y = 0.04. Very efficient energy transfer (ET) from Ce3+ to Eu2+ appeared in the Ce3+-Eu2+ codoped samples, and the yellow emission of Eu2+ can be further enhanced by this ET. The thermal-quenching luminescence of the as-prepared samples was evaluated by the temperature-dependent emission spectra, which indicated that the introduction of Sr2+ can improve the thermally luminescence stability of Eu2+. The fabrication of the LEDs device revealed that the Ce3+-Eu2+ activated samples in this work could show potential applications in white LEDs.