Xiuhong Pan

Effect of Yb 3+ on the upconversion luminescence of Tm 3+ /Yb 3+ co-doped La 2 O 3 -TiO 2 -ZrO 2 glasses

Containerless processing has been used to prepare Tm3+/Yb3+ co-doped La2O3-TiO2-ZrO2 (LTZ) glasses with intense blue emission. The effects of Yb3+ ions on the thermal stability and upconversion luminescence of as-prepared LTZ glasses and glass-ceramics have been studied. Yb3+ ions perform negative effect on the thermal stability of glasses. As Yb3+ increases, the emissions can be enhanced by improving energy transfer from Yb3+ to Tm3+ and reducing energy loss. A model is proposed to discuss the effects of active ions, sensitizers, and hosts on the upconversion luminescence process. Moreover, the refractive index value and Abbe number of glasses are 2.261 and 20.7, indicating excellent optical properties.

Investigation of upconversion luminescence in Er 3+ /Yb 3+ co-doped Nb 2 O 5 -based glasses prepared by aerodynamic levitation method

The aerodynamic levitation method has been employed to fabricate Er3+/Yb3+ co-doped Nb2O5-La2O3-Ta2O5 glasses. The maximum phonon energy is about 735 cm−1 and the phonon density decreases with the increase of Yb3+. Small phonon density is favorable for upconversion luminescence. The absorption intensity at ~976 nm is improved by Yb3+. The glasses show high thermal stability and glass forming ability is enhanced by Yb3+. Green, red, and near infrared emissions are obtained and upconversion luminescence increases with Yb3+, which agrees well with the analysis of Raman and absorption spectra. As Yb3+ increases, the lifetime is enhanced. The results of lifetime measurement confirm the tendency of upconversion luminescence with Yb3+ ions.

Crystallization mechanism and kinetics of mayenite glass prepared by aerodynamic levitation method

The mayenite glass with a wide high-temperature stability (ΔT=131∘C) was innovatively synthesized by the aerodynamic levitation (ADL) containerless technique without conventional glass-forming addictives. The crystallization mechanism and kinetics of mayenite glass were studied by X-ray diffraction (XRD), scaning electron microscopy (SEM), Raman spectra and differential scanning calorimetry (DSC) analysis. The crystallization mechanism study revealed that structure and morphology mainly evolved near the crystallization peak temperature by the networking process of isolated AlO4 tetrahedra units, resulting in the growth mechanism changing from “two-dimensional” to “three-dimensional”. Crystallization kinetics calculations based on the non-isothermal Matusita model indicated that the activation energy for the crystallization of mayenite glass was 844kJ⋅mol−1. The calculated growth morphology parameters (m and n) also confirmed the surface crystallization along with bulk crystallization mechanism for the may...

Study on Upconversion and Thermal Properties of Tm3+/Yb3+ Co-Doped La2O3-Nb2O5-Ta2O5 Glasses

The effect of Yb3+ ions on upconversion luminescence and thermal properties of Tm3+/Yb3+ co-doped La2O3-Nb2O5-Ta2O5 glasses has been studied. Glass transition temperature is around 740 °C, indicating high thermal stability. The effect of Yb3+ ions on the thermal stability is not obvious. Both the glass forming ability and the upconversion luminescence first increase and then decrease with the increase of Yb3+ ions. The glasses perform low glass forming ability with ΔT around 55 °C. Blue and red emissions centered around 477, 651, and 706 nm are obtained at the excitation of 976 nm laser. The upconversion luminescence mechanism is energy transfer from Yb3+ to Tm3+ mixed with two- and three- photon processes. The thermal kinetic Differential Thermal Analysis (DTA)-analysis indicates that the average activation energy first increases and then decreases with the increase of Yb3+ ions. This result can be introduced in order to improve upconversion luminescence of glasses by crystallization in the future. Tm3+/Yb3+ co-doped La2O3-Nb2O5-Ta2O5 glasses with good upconversion and thermal properties show promising applications in solid-state laser, optical temperature sensing.

Preparation and Upconversion Luminescence of Nd 3+ /Yb 3+ Co-doped La 2 O 3 -TiO 2 -ZrO 2 Glass-ceramics: Preparation and Upconversion Luminescence of Nd 3+ /Yb 3+ Co-doped La 2 O 3 -TiO 2 -ZrO 2 Glass-ceramics

利用气悬浮方法制备了Nd 3+ /Yb 3+ 共掺La 2 O 3 -TiO 2 -ZrO 2 前驱体玻璃, 通过热处理获得了微晶玻璃。通过DTA对前驱体玻璃的热稳定性进行了研究。利用光致发光谱, TEM和EDS对微晶玻璃进行了表征分析, 并研究了热处理对上转换发光的影响。结果表明: 玻璃转变温度和析晶起始温度分别为799℃和880℃. 在980 nm激光激发下, 样品发射出中心位于497, 523, 545, 603和657 nm处的五条发光带。热处理后样品上转换发光强度提高, 经过880℃保温50 min热处理的微晶玻璃显示了最强的上转换发光, 在545 nm处的发光强度是前驱体玻璃的11倍, 这是由于在微晶玻璃基质中存在致密柱状晶和Nd 3+ 离子在晶体中富集造成的。利用气悬浮方法制备了Nd 3+ /Yb 3+ 共掺La 2 O 3 -TiO 2 -ZrO 2 前驱体玻璃, 通过热处理获得了微晶玻璃。通过DTA对前驱体玻璃的热稳定性进行了研究。利用光致发光谱, TEM和EDS对微晶玻璃进行了表征分析, 并研究了热处理对上转换发光的影响。结果表明: 玻璃转变温度和析晶起始温度分别为799℃和880℃. 在980 nm激光激发下, 样品发射出中心位于497 nm, 523 nm, 545 nm, 603 nm 和657 nm共五条发光带。热处理提高了上转换发光强度, 经过880℃保温50 min热处理的微晶玻璃显示了最强的上转换发光, 在545 nm处的发光强度是前驱体玻璃的11倍。经分析原因发现, 这是由于在微晶玻璃基质中存在致密柱状晶和Nd 3+ 离子在晶体中富集造成的。