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A novel white Y2(Ti0.8Hf0.2)2O7: Eu phosphors regulated by HfO2 exhibiting low color shifting for high temperature.

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Bibliographic Details
Title:	A novel white Y2(Ti0.8Hf0.2)2O7: Eu phosphors regulated by HfO2 exhibiting low color shifting for high temperature.
Authors:	Han, Zhanwen¹ (AUTHOR), Yu, Hongquan¹ (AUTHOR) yuhq7808@126.com, Liu, Tianshuo² (AUTHOR), Sun, Jiashi¹ (AUTHOR), Li, Xiangping¹ (AUTHOR) lixp@dlmu.edu.cn, Chen, Baojiu¹ (AUTHOR) bjchen@dlmu.edu.cn
Source:	Spectrochimica Acta Part A: Molecular & Biomolecular Spectroscopy. Dec2024, Vol. 323, pN.PAG-N.PAG. 1p.
Subjects:	Low temperatures, Visible spectra, Reducing agents, Color temperature, High temperatures
Abstract:	White Y 2 (Ti 0.8 Hf 0.2) 2 O 7 :0.2Eu phosphors exhibit a high color rendering index (Ra = 83–90.2), low color temperature (CCT = 4243 K), and low color shifting (Δ s = 2.83 × 10−2) at 503 K, and are suitable for use in white LED devices. [Display omitted] • White Y 2 (Ti 0.8 Hf 0.2) 2 O 7 :Eu phosphors with low color shifting under high temperature (503 K) were synthesized. • The formation of Eu2+ ions was caused by the introduction of HfO 2 and did not require additional reducing agents. • Y 2 (Ti 0.8 Hf 0.2) 2 O 7 :0.2Eu phosphors exhibit a high color rendering index (Ra = 83–90.2) and low color shifting (Δ s =2.83 × 10−2) under high temperature. • The WLED device exhibits good color coordinates (0.345, 0.358) and a high Ra value of 90.1 at a 300 mA current. The development of white phosphors that can be activated in near-ultraviolet light is highly important in the field of LED lighting. In this work, a series of color-tunable Y 2 (Ti 1-x Hf x) 2 O 7 :Eu phosphors were prepared by adjusting the HfO 2 and Eu3+ concentrations. In particular, white Y 2 (Ti 0.8 Hf 0.2) 2 O 7 :Eu phosphors were successfully synthesized and emitted a broad band covering the entire visible light region upon excitation with 340 nm UV light. The white banded materials were composed of Eu2+ and Eu3+ emissions and HfO 2 defect emission. The formation of Eu2+ ions was caused by the introduction of HfO 2, which causes self-reduction of Eu3+ ions but does not require additional reducing agents. The white Y 2 (Ti 0.8 Hf 0.2) 2 O 7 :Eu phosphors exhibit low color shifting at high temperature, which is very important for LED applications. The chromaticity shift of the Y 2 (Ti 0.8 Hf 0.2) 2 O 7 :0.2Eu phosphor is 2.83 × 10−2 at 503 K, which is only 54.8 % that of commercial three-color white phosphors at the same temperature. The Ra value did not decrease significantly with increasing temperature and reached 90.2 at 383 K. Y 2 (Ti 0.8 Hf 0.2) 2 O 7 :0.2Eu phosphors were assembled with a 365 nm LED chip to fabricate a WLED device that showed excellent white-colored coordinates (0.345, 0.358) and a high Ra value of 90.1 under a 300 mA current. [ABSTRACT FROM AUTHOR]
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Database:	Engineering Source

Description
Abstract:	White Y 2 (Ti 0.8 Hf 0.2) 2 O 7 :0.2Eu phosphors exhibit a high color rendering index (Ra = 83–90.2), low color temperature (CCT = 4243 K), and low color shifting (Δ s = 2.83 × 10−2) at 503 K, and are suitable for use in white LED devices. [Display omitted] • White Y 2 (Ti 0.8 Hf 0.2) 2 O 7 :Eu phosphors with low color shifting under high temperature (503 K) were synthesized. • The formation of Eu2+ ions was caused by the introduction of HfO 2 and did not require additional reducing agents. • Y 2 (Ti 0.8 Hf 0.2) 2 O 7 :0.2Eu phosphors exhibit a high color rendering index (Ra = 83–90.2) and low color shifting (Δ s =2.83 × 10−2) under high temperature. • The WLED device exhibits good color coordinates (0.345, 0.358) and a high Ra value of 90.1 at a 300 mA current. The development of white phosphors that can be activated in near-ultraviolet light is highly important in the field of LED lighting. In this work, a series of color-tunable Y 2 (Ti 1-x Hf x) 2 O 7 :Eu phosphors were prepared by adjusting the HfO 2 and Eu3+ concentrations. In particular, white Y 2 (Ti 0.8 Hf 0.2) 2 O 7 :Eu phosphors were successfully synthesized and emitted a broad band covering the entire visible light region upon excitation with 340 nm UV light. The white banded materials were composed of Eu2+ and Eu3+ emissions and HfO 2 defect emission. The formation of Eu2+ ions was caused by the introduction of HfO 2, which causes self-reduction of Eu3+ ions but does not require additional reducing agents. The white Y 2 (Ti 0.8 Hf 0.2) 2 O 7 :Eu phosphors exhibit low color shifting at high temperature, which is very important for LED applications. The chromaticity shift of the Y 2 (Ti 0.8 Hf 0.2) 2 O 7 :0.2Eu phosphor is 2.83 × 10−2 at 503 K, which is only 54.8 % that of commercial three-color white phosphors at the same temperature. The Ra value did not decrease significantly with increasing temperature and reached 90.2 at 383 K. Y 2 (Ti 0.8 Hf 0.2) 2 O 7 :0.2Eu phosphors were assembled with a 365 nm LED chip to fabricate a WLED device that showed excellent white-colored coordinates (0.345, 0.358) and a high Ra value of 90.1 under a 300 mA current. [ABSTRACT FROM AUTHOR]
ISSN:	13861425
DOI:	10.1016/j.saa.2024.124935