Ping Wang,Bin Duan,Yuanyuan Fan,Min Luo,Liming Tang,Changchun Ding,Tong Liu,Wei Jin,Junshan Hu
A novel upconversion phosphor, Ca 3 (VO 4 ) 2 co-doped with Yb 3+ and Er 3+ , was successfully synthesized via a high-temperature solid-state method. Under 980 nm near-infrared excitation, this material exhibits remarkable upconversion luminescence, with intense green emissions at 527 nm and 550 nm, and a weaker red emission at 657 nm. The optimal doping concentrations were determined to be 0.03 for Yb 3+ and 0.005 for Er 3+ , enabling maximum luminescent efficiency. Spectroscopic investigations including upconversion photoluminescence, excitation, and emission spectra confirmed that the upconversion follows a distinct energy transfer mechanism: Yb 3+ ( 2 F 5/2 ) + Er 3+ ( 4 I 11/2 ) → Yb 3+ ( 2 F 7/2 ) + Er 3+ ( 4 F 7/2 ). In addition to its excellent luminescent properties, the Ca 3 (VO 4 ) 2 : 0.03Yb 3+ /0.005Er 3+ phosphor exhibits reliable optical thermal sensitivity over a wide temperature range (298–673 K), with a peak relative sensitivity of 1.11 % K −1 at 298 K. These outstanding optical characteristics make Ca 3 (VO 4 ) 2 : 0.03Yb 3+ /0.005Er 3+ a promising candidate for display and lighting technologies.
Yunyi Lu,Chenqi Kang,Zhenxiang Ye,Lehui Liu,Feifei Yuan,Yisheng Huang,Lizhen Zhang,Zhoubin Lin
This paper presents a method that employs charge compensation to effectively enhance the spectral, mechanical, and thermal properties of Cr 3+ : Ca 3 (VO 4 ) 2 (Cr:CVO) crystals. Due to doping with heterovalent ions, a significant number of oxygen vacancies are present in the Cr:CVO crystals, resulting in strong self-absorption and suppression of emission at 842 nm. To address this issue, Li + ions were introduced as charge compensators. When the concentration of Li + ions reached 5 at%, self-absorption was most effectively suppressed, and the emission at 842 nm was significantly enhanced. Additionally, the mechanical and thermal properties of the crystal are significantly improved. The XPS research results indicate that changes in the color, spectra, and physical properties of Cr:CVO crystals primarily depend on the relative concentration of oxygen vacancies within them. Both annealing and the introduction of Li + ions effectively reduce the high concentration of oxygen vacancies in Cr:CVO crystals. However, the strategy of Li + ion charge compensation is more effective than annealing in comprehensively enhancing the overall performance of Cr:CVO crystals. This study presents an effective strategy for defect regulation and performance optimization in Cr 3+ -doped oxide laser crystals.
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