Achieving white emission by site-selective occupation of Eu2+ in K2BaSr(PO4)2−x(BO3)x:Eu2+

Abstract

Efficient regulation of activator site occupation is crucial for developing white light phosphors with excellent luminous properties. Herein, we report the synthesis of new borophosphate K2BaSr(PO4)2−x(BO3)x:0.04Eu2+ phosphors via an anion group substitution strategy. In the pristine sample, there are three different cationic sites (Ba2+, Sr2+, and K+) with different coordination environments where Eu2+ can occupy the Ba2+ and/or Sr2+ sites. In the process of (BO3)3− partially substituting (PO4)3− units, owing to the effect of increased cation disorder generated from the difference in geometric configurations between the two anion groups, a new emission band centering at around 535 nm appears in the emission spectra. The intensity of this band increases as more (PO4)3− units are substituted by (BO3)3−, resulting in the phosphor emission tuned from blue to white by controlling the (BO3)3− concentration. This emission band can be attributed to the occupation of Eu2+ at the K+ sites induced by cation disorder through the analysis of structural and photoluminescence properties and first-principles calculations, except for the co-occupation of Eu2+ with Ba and Sr sites. A phosphor-converted LED (pc-LED) has been successfully fabricated using the phosphor at optimized compositions, K2BaSr(PO4)1.8(BO3)0.2:0.04Eu2+, and a 365 nm near-ultraviolet chip, exhibiting a color rendering index of 81.3 and a correlated color temperature of 7024 K. Our findings demonstrate the effectiveness of the anion group modulation for developing new high-performance LED phosphors.

Graphical abstract: Achieving white emission by site-selective occupation of Eu2+ in K2BaSr(PO4)2−x(BO3)x:Eu2+

Supplementary files

Article information

Article type
Paper
Submitted
17 Aug 2024
Accepted
28 Sep 2024
First published
01 Oct 2024

J. Mater. Chem. C, 2024, Advance Article

Achieving white emission by site-selective occupation of Eu2+ in K2BaSr(PO4)2−x(BO3)x:Eu2+

G. Xie, J. Si, G. Li, G. Cai, Z. Wang and X. Wang, J. Mater. Chem. C, 2024, Advance Article , DOI: 10.1039/D4TC03517H

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