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以Cr 3+为激活剂的荧光粉被认为是目前最有可能实现商业化的近红外材料. 但目前这类荧光粉的发射波长一般位于小于850 nm的近红外一区, 以Cr 3+为激活剂实现近红外二区发射仍然具有挑战. 本文采用普适的固相法制备了一系列Na 3Y 1–xSi 3O 9: xCr 3+硅酸盐荧光粉, 利用Na 3YSi 3O 9硅酸盐属性及结构中多种适于Cr 3+占据的八面体位点有效红移并展宽光谱. 对样品的物相、晶体结构、微观形貌、光致发光、主发射峰衰减和热稳定性等进行了系统研究. 结果显示, 所制样品均为纯相, 形貌不均匀略有团聚, 尺寸在微米量级. Cr 3+在Na 3YSi 3O 9晶格中位于弱晶体场环境, 八面体晶体场参数 Dq和Racah参数 B的比值 Dq/ B= 2.29. 在485 nm蓝光激发下Na 3Y 1–xSi 3O 9: xCr 3+荧光粉最强发射峰位于984 nm处(NIR II区), 长于大多数Cr 3+激活的荧光粉. 且得益于Cr 3+在晶格中的多格位占据, 发射光谱的半峰宽高达183 nm. Na 3Y 1–xSi 3O 9: xCr 3+中最佳掺杂浓度为3%, 猝灭机理为Cr 3+离子间的偶极-偶极作用. Na 3Y 1–xSi 3O 9: xCr 3+主发射峰荧光衰减动力学分析表明室温荧光寿命约为37.95 μs, 且随着掺杂浓度增大及温度升高(至423 K)逐渐降低.Phosphors-converted near-infrared LED (pc-NIR LED) possesses applications in various fields including food quality analysis, night vision, biomedical imaging, and biomedicine. The design and development of broadband near-infrared (NIR) phosphors with the required properties are of decisive significance for pc-NIR LED devices. The Cr 3+doped phosphors are considered to be most promising near-infrared materials for commercialization. Broadband NIR luminescent materials doped with Cr 3+have attracted more and more attention due to their potential applications in NIR light sources. However, the emission wavelength of Cr 3+doped phosphor is generally located in the NIR I region of less than 850 nm, and realizing the NIR II region emission is still a challenge. In this work, a series of Cr 3+doped Na 3YSi 3O 9new silicate phosphors is prepared by solid-state method in N 2atmosphere at 1150 ℃ for 8 h. We take advantages of the silicate nature and the multi octahedral sites suitable for Cr 3+in the studied Na 3YSi 3O 9materials to redshift and broaden the spectrum. The phase, crystal structure, microstructure, photoluminescence, main emission peak decay and thermal stability of the samples are systematically studied. The results show that the prepared samples are pure phases, with uneven morphology, slight agglomeration, and the sizes in the micrometer range. The Cr 3+is located in the weak crystal field environment of Na 3YSi 3O 9lattice, with a Dq/ Bvalue of 2.29. Under the excitation of blue light at a wavelength of 485 nm, the strongest emission peaks of Na 3Y 1–xSi 3O 9: xCr 3+phosphors are located at 984 nm (NIR II region), which is longer than those of most Cr 3+activated phosphors. Due to the multi-site occupation of Cr 3+in the lattice, the full width at half maximum (FWHM) of the emission spectrum is as high as 183 nm. The optimal doping concentration of Na 3Y 1–xSi 3O 9: xCr 3+is 3%, and the quenching mechanism is the dipole-dipole interaction between Cr 3+ions. Fluorescence decay curves show that the luminescence lifetime of Na 3Y 0.97Si 3O 9:0.03Cr 3+sample gradually decreases with the increase of doping concentration and temperature. The results of the temperature-dependent spectra show that the emission intensity decreases in a temperature range from 298 K to 423 K, and the activation energy Δ Eof Cr 3+is 0.157 eV.
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Keywords:
- silicate/
- Cr3+/
- broadband near-Infrared/
- multi-sites
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Chemical formula Na3YSi3O9 Na3Y0.97Si3O9:0.03Cr3+ Space group P212121 P212121 a/Å 15.408(4) 15.0362(4) b/Å 15.312(5) 15.2116(5) c/Å 15.222(4) 15.1460(4) α/(°) 90 90 β/(°) 90 90 γ/(°) 90 90 V/Å3 3591.016(18) 3464.26(18) Rp/% — 4.75 Rwp/% — 7.41 χ2 — 2.140 
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Bond d1 d2 d3 d4 d5 d6 dav ddis Y1—O 2.4937 2.1867 2.0643 2.2623 3.1427 3.0236 2.2589 0.1461 Y2—O 2.1108 2.2302 2.2744 2.8329 2.1218 2.1108 2.2801 0.0808 Y3—O 2.2707 1.9528 2.7648 1.8012 3.8077 2.8960 2.5822 0.2223 Y4—O 2.2642 2.052 1.6169 1.8874 3.1401 3.2249 2.3643 0.2307 下载:
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浓度 λem/nm A1 A2 τ1 τ2 χ2 τ/μs 0.005 984 2020.38 802.09 16.50 54.35 0.987 37.95 0.01 984 1993.95 836.83 15.08 50.03 1.054 35.42 0.02 984 1808.84 729.58 12.14 44.47 1.059 31.42 0.03 984 1963.30 726.19 12.61 45.56 0.961 31.45 0.05 984 1837.09 818.42 13.02 43.06 0.986 30.91 0.10 984 1985.01 692.64 13.29 45.20 0.984 30.61 下载:
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