The influence of Pb-doping on the crystal structure and luminescence properties of LiEuMo₂O₈ red-emitting phosphors

详细信息    查看全文

• 作者：Pengpeng Dai ^{daipp614@nenu.edu.cn" class="auth_mail" title="E-mail the corresponding author}
• 关键词：Molybdate ; Sensitizer ions ; Luminescence ; White-light LED
• 刊名：Ceramics International
• 出版年：2017
• 出版时间：January 2017
• 年：2017
• 卷：43
• 期：1
• 页码：1565-1570
• 全文大小：1090 K

文摘

High efficiency red phosphors, showing spectral range of 610–620 nm and a narrow-line emission, are helpful for achieving high color rendering index (CRI) and low correlated color temperature (CCT) phosphor-converted white-light diodes. Red phosphors activated by trivalent europium (Eu³⁺) thus have attracted a renewed interest for pc-WLEDs. In our case, we prepare a series of Pb²⁺-doped LiEuMoO₈ red-emitting phosphors by solid-state reactions. The introduction of Pb²⁺ ions expands and distorts slightly the unit cell volume of LiEuMo₂O₈ matrix, and red-shifts the charge transfer absorption (CTA) band of LiEuMo₂O₈, which are demonstrated by X-ray powder diffraction, absorption spectra and micro-Raman spectra. Photoluminescence and photoluminescence excitation spectra results show that the excitation efficiency of Eu³⁺ is improved significantly in the near ultraviolet region when Pb²⁺ ions are doped into the host lattice. At x=0.015, the red-emitting intensity of LiEuMo₂O₈ is enhanced by 50%, and the internal quantum yields is 53% under excitation at 395 nm. The enhanced red emission is discussed in term of the relaxation of parity-forbidden selection rules for trivalent europium luminescent center, and the sensitization effect of Pb²⁺ as a sensitizer for Eu³⁺ ions is negligible in LiEuMo₂O₈ under near ultraviolet excitation.