Ca<sub>9–<i>y</i></sub>Mg<sub><i>y</i></sub>NaGd<sub>0.667</sub>(PO<sub>4</sub>)<sub>7</sub>:Eu<sup>2+</sup>: A Single Eu<sup>2+</sup>-Doped Full-Spectrum White Light Emission Phosphor with High Color Rendering Index
Luo Zhou, Haifeng Zou, Zhibo Zheng, Yanxia Zhao, Chao Wang, Qinghai Sun, Yanhua Song
Abstract
The multi-cationic site occupation control of rare earth doped phosphor materials is one of the key factors in achieving single-phase full-spectrum emission. In this work, the site distribution of Eu 2+ in Ca 9 NaGd 0.667 (PO 4 ) 7 (CNGP): x %Eu 2+ phosphors with multi-cationic sites was determined. Under 385 nm excitation, CNGP: x %Eu 2+ samples exhibited a cyan emission composed of three sub-Gaussian components. The CNGP:1.5%Eu 2+ phosphor was structurally modified through the partial substitution of Mg 2+ for Ca 2+ according to the crystallographic site engineering theory, and corresponding luminescent properties had been adjusted. When the concentration of Mg 2+ changed, the Ca 9– y Mg y NaGd 0.667 (PO 4 ) 7:1.5%Eu 2+ (CNGPE: y Mg 2+ ) phosphors exhibited a tunable emission from cyan to orange and achieved white light emission at y = 0.6. Based on the change of the crystal field environment, the mechanism of Mg 2+ substitution affecting the luminescence characteristics of CNGP: x %Eu 2+ phosphors was researched in detail. The light-emitting diode device consisted of a CNGPE:0.6Mg 2+ phosphor and a 385 nm chip and had a high color rendering index (CRI = 91.9), low correlated color temperature (CCT = 4852 K), and excellent color stability. The optical performance of this device makes it promising to be used in full spectrum lighting.