Eu2+-Activated Sr8ZnSc(PO4)7: A Novel Near-Ultraviolet Converting Yellow-Emitting Phosphor for White Light-Emitting Diodes

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• 作者：Chien-Hao Huang ; Yi-Chen Chiu ; Yao-Tsung Yeh ; Ting-Shan Chan ; Teng-Ming Chen
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2012
• 出版时间：December 26, 2012
• 年：2012
• 卷：4
• 期：12
• 页码：6661-6668
• 全文大小：567K
• 年卷期：v.4,no.12(December 26, 2012)
• ISSN：1944-8252

文摘

The crystal structure of Eu²⁺-activated Sr₈ZnSc(PO₄)₇:Eu²⁺ phosphor was refined and determined from XRD profiles by the Rietveld refinement method using a synchrotron light source. This phosphor crystallizes in the monoclinic structure with the I2/a space group. The SZSP:xEu²⁺ phosphors showed a broad yellow emission band centered at 511 and 571 nm depending on the concentration of Eu²⁺, and the composition-optimized concentration of Eu²⁺ in the Sr₈ZnSc(PO₄)₇:Eu²⁺ phosphor was determined to be 2 mol %. The estimated crystal-field splitting and CIE chromaticity coordinates of Sr₈ZnSc(PO₄)₇:xEu²⁺ (x = 0.001鈥?.05 mol) were 20181鈥?0983 cm^鈥? and (0.3835, 0.5074) to (0.4221, 0.5012), respectively, and the emission band showed a redshift from 547 to 571 nm with increasing Eu²⁺ concentration. The nonradiative transitions between the Eu²⁺ ions in the Sr₈ZnSc(PO₄)₇ host were attributable to dipole鈥揹ipole interactions, and the critical distance was approximately 19.8 脜. The combination of a 400 nm NUV chip with a blend of Sr₈ZnSc(PO₄)₇:0.02Eu²⁺ and BAM:Eu²⁺ phosphors (light converters) gave high color rendering indices between 79.38 and 92.88, correlated color temperatures between 4325 and 7937 K, and tuned CIE chromaticity coordinates in the range (0.381, 0.435) to (0.294, 0.310), respectively, depending on the SZSP:0.02Eu²⁺/BAM:Eu²⁺ weight ratio. These results suggest that the Sr₈ZnSc(PO₄)₇:0.02Eu²⁺/BAM:Eu²⁺ phosphor blend has potential applications in white NUV LEDs.

Keywords:

Sr₈ZnSc(PO₄)₇; yellow-emitting; Eu²⁺; NUV; white LED; photoluminescence