Synthesis and luminescence enhancement of CaLa0.6(MoO4)1.9:Eu3+ red-emitting phosphors by Bi3+ doping for white LEDs

• Published in: Journal of solid state chemistry Vol. 301; p. 122334
• Main Authors: Sangang, Lou, Xuan, Xiao, Yu, Jiao, Chengxiao, Hu, Kehui, Qiu
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 01.09.2021
• Subjects: Molybdate; Photoluminescence; Red phosphors; White LEDs; Red phosphors; Molybdate; Photoluminescence; White LEDs
• ISSN: 0022-4596; 1095-726X
• DOI: 10.1016/j.jssc.2021.122334

A series of novel CaLax(MoO4)1.5x+1:Eu3+ and CaLa0.6(MoO4)1.9:Eu3+,Bi3+ phosphors were synthesized through the combustion method. This study investigated the morphology, phase structure, and photoluminescence properties. All the as-prepared samples have a tetragonal structure and compatible with standard CaMoO4, belonging to the I41/a space group. The CaLa0.6(MoO4)1.9:Eu3+ (hereafter referred to as CLMO:Eu3+) phosphor possessed the strongest red emission intensity within CaLax(MoO4)1.5x+1:Eu3+ phosphors under the 393 ​nm near-ultraviolet light excited. Furthermore, the CLMO:Eu3+ phosphor showed the highest emission peak at 618 ​nm among emission peaks, which was attributed to the 5D0→7F2 transition of Eu3+. When Eu3+ was doped with 13 ​mol%, the synthesized sample had strongest red emission intensity. Moreover, Bi3+ was added into the CLMO:13%Eu3+ phosphor to improve the red color emission intensity due to the sensitization of Bi3+ to Eu3+, the maximum luminescence intensity was reached when the Bi3+ concentration was 4 ​mol%. The color purity of CLMO:13%Eu3+,4%Bi3+ phosphor reached 94.3% the emission intensity at 150 ​°C was 73.3% of that at 25 ​°C, and the activation energy of thermal quenching was 0.27 ​eV. All results indicated that the prepared phosphors could be applied as a potential red component of the w-LEDs excited by near-ultraviolet InGaN chips. A novel n-UV light excited scheelite-type CaLa0.6(MoO4)1.9:Eu3+,Bi3+ red phosphors with a higher thermal stability and color purity were reported for application in w-LEDs. [Display omitted] •Single phase CaLax(MoO4)1.5x+1:Eu3+ series phosphors have been fabricated via a combustion method.•Structural properties thoroughly discussed by XRD, SEM and XRD Rietveld refinement.•The intensity ratio of red to orange light and their dependence on Eu3+ surrounding environment have been explained.•Bi3+ co-doped to improve luminescence intensity and enhance mechanism also studied.