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Fabrication and Optical Properties of 2at.%Yb:LuYAG Mixed Crystal through Nanocrystalline Powders
摘要： Ytterbium doped Lu1.5Y1.5Al5O12 (LuYAG) nanocrystalline powders were synthesized by a wet chemical mixed precipitant co-precipitation (MPP) method, and then the mixed crystal of Yb:LuYAG was grown in an optical floating zone (OFZ) furnace at the speed of 6–10 mm/h, using a [111] oriented YAG seed crystal. The transmittance of the polished LuYAG crystal is close to the ideal value of LuAG or YAG. The X-ray rocking curve shows complete symmetry and the full width at half maximum (FWHM) is 10 arc-second, indicating the good quality of as grown Yb:LuYAG multicomponent garnet crystal. The thermal luminescent spectrum at room temperature shows four deep energy traps at around 1–1.3 eV. X-ray excited luminesce (XEL) spectra is measured to characterize the existence of LuAl or YAl shadow defects in the bulk single crystal. The emission peak at around 320 nm indicates that the LuYAG crystal prepared by OFZ have lower concentrations of antisite defects (AD) with respect to its Czochralski counterpart.
关键词： crystal growth,optical floating zone,LuYAG,optical properties
更新于2025-09-23 15:22:29
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Pushing Boundaries: High Pressure, Supercritical Optical Floating Zone Materials Discovery
摘要： In this perspective review, we provide the rationale for utilizing supercritical fluids for solid state materials discovery in the context of recent advances in the field of high pressure synthesis. We discuss the importance of the transition from gas-like to solvent-like environments in which materials synthesis and crystallization is occurring, the appropriate conceptual frameworks for its impact on synthesis and directional solidification, and dispel popular myths. We provide an overview of materials that have been grown in single crystal form by the high pressure optical floating zone technique, report the first successful stable molten zone in an optical furnace at P = 300 bar, and show viability of the traveling solvent method even with high fluid pressures. Further, we report on some unexpected observations found in the highly dynamic synthesis environment of supercritical fluids, enabled by the ability to observe, in real time, materials behavior. Finally, we offer a perspective on the scientific domains opened by these new capabilities.
关键词： Single crystal growth,Materials discovery,Optical floating zone,High pressure synthesis,Supercritical fluids
更新于2025-09-23 15:19:57
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Growth and Characterization of High-Melting Sesquioxides for 3 μm Lasers
摘要： Due to the strong absorption in water, lasers in the wavelength range of 3 μm are attractive in fields like laser surgery or atmospheric detection. To achieve good beam quality and stable high-power laser operation, good mechanical, optical and thermal properties are essential for potential host materials. Rare-earth sesquioxide crystals are very suitable for high-power mid-infrared applications due to their high thermal conductivity and low phonon energies. In 2012 Er-doped lutetia (Lu2O3) was introduced as an efficient 3 μm laser material [1]. Due to its good thermo-mechanical properties, this materials allowed for the highest room-temperature laser power of any Er-doped crystalline host material at the time. Also other cubic sesquioxide host materials such as scandia (Sc2O3) and yttria (Y2O3) are very promising in this respect [2, 3]. However, the growth of sesquioxides is very challenging owing to their high melting temperatures of more than 2400 °C. These materials were previously grown by the heat exchanger method (HEM), where rhenium is the only suitable crucible material [4]. This method yields good results, but is very demanding as it requires a very precise control of the growth atmosphere to prevent damage of the very expensive Re-crucibles. For these reasons, HEM is not suitable for commercial sesquioxide growth. Here, we report on the optical floating zone method (OFZ) as alternative technique for the growth of sesquioxide crystals to avoid the use of expensive and sensitive crucible materials. This method has advantages over the HEM technique such as no crucible and insulation are required and high oxygen partial pressures are possible. By using a high-pressure high-temperature OFZ furnace Lu2O3 and Er3+-doped Lu2O3 crystals were grown (Fig.1). The crystals were widely free of color centers and single crystalline, the crystal shown in Fig. 1b even shows a pronounced faceting of the outer shape. The samples in these initial experiments had diameters of ~ 5 mm and several cm length, however, our OFZ furnace is specified for growing also larger diameters. The growth experiments were carried out by using Ar atmosphere at elevated pressure, the growth speed was varied between 2 and 7.5 mm/h at a heating lamp power of 5 kW. For the feeding rods we used sintered cold isostatically pressed green bodies of the desired composition and size. This route was chosen to avoid contamination of the 5N starting materials. In future, we aim to utilize these crystals for laser experiments to advance the progress of 3 μm laser operation with Er3+ -doped sesquioxides. In particular yttria is very attractive in this respect due to the low prices of high purity starting materials, however, a phase transition in the range of the melting point led to insufficient crystal quality in previous growth attempts from the crucible. By utilizing the OFZ-method we hope to be able to circumvent this phase transition by better control of the thermal gradients within the growing crystal.
关键词： optical floating zone method,sesquioxides,Er-doped lutetia,3 μm lasers,high-melting materials
更新于2025-09-12 10:27:22