The hydrothermal synthesis and characterization of 10%Yb³⁺:LiLuF₄ (LLF) microcrystals are reported. A combination of X-ray diffraction (XRD) analysis, analytical transmission electron microscopy (TEM), scanning TEM (STEM), energy-dispersive X-ray (EDX) spectroscopy), temperature-dependent Fourier-transform infrared (FTIR) spectroscopy, and photoluminescence (PL) measurements confirm a scheelite (I4₁/a) phase and substitutional doping of Yb³⁺ within the microcrystals. Laser cooling to more than 20 K below room temperature in vacuum (10⁻³ torr) is demonstrated when irradiating individual microcrystals using a near-infrared pumping wavelength (λ = 1020nm) at a laser power of 40 mW (irradiance of 0.85 MW cm⁻²). The use of these microcrystals is further demonstrated for solid-state laser refrigeration of an electron-transparent silicon-nitride (Si₃N₄) TEM window. A combination of internal luminescence thermometry, heat-transfer modeling, and control measurements on lithographically patterned Si₃N₄ optical cavities is used to demonstrate successful bulk laser cooling of Si₃N₄ TEM windows by ≈15 K below room temperature, opening new opportunities for contactless in situ TEM refrigeration.

中文翻译：

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Yb3+: LuLiF4 微晶的水热合成和 Yb3+: LuLiF4/氮化硅复合纳米结构的激光制冷

报道了 10%Yb ³⁺ :LiLuF ₄ (LLF) 微晶的水热合成和表征。X 射线衍射 (XRD) 分析、分析透射电子显微镜 (TEM)、扫描 TEM (STEM)、能量色散 X 射线 (EDX) 光谱)、温度相关傅里叶变换红外 (FTIR) 光谱的组合，和光致发光 (PL) 测量证实了白钨矿 ( I 4 ₁ / a ) 相和 Yb ³⁺在微晶内的置换掺杂。激光冷却至低于室温下在真空（10超过为20K ^-3 乇）证明了使用近红外泵浦波长照射个体微晶时（λ= 1020nm），激光功率为 40 mW（辐照度为 0.85 MW cm ^-2）。这些微晶的使用进一步证明用于电子透明氮化硅 (Si ₃ N ₄ ) TEM 窗口的固态激光制冷。对光刻图案化的 Si ₃ N ₄光学腔进行内部发光温度测量、传热建模和控制测量的组合，用于证明 Si ₃ N ₄ TEM 窗口的体激光成功冷却低于室温约 15 K，开辟了新的机会用于非接触式原位 TEM 制冷。