硅酸盐学报2024，Vol.52Issue(3)：1006-1022,17.DOI:10.14062/j.issn.0454-5648.20230664
倍半氧化物激光陶瓷的研究进展
Research Progress on Sesquioxide Laser Ceramics
摘要
Abstract
Solid-state lasers have the advantages of realizing laser outputs with a high energy and a high peak power,having potential applications in civil and military fields(i.e.,remote sensing,environmental monitoring,medical treatment and optoelectronic countermeasure).Rare-earth ions doped sesquioxide materials as one of the most promising gain media have attracted recent attention due to their low phonon energy,low thermal expansion coefficient and high thermal conductivity.However,large-size sesquioxide single crystals with a good optical quality are difficult to grow because of the high melting points(i.e.,＞2 400 ℃)and phase transition point at 2280 ℃.Fortunately,the sintering of sesquioxide ceramics as an alternative way to prepare laser host materials.It is possible to obtain the materials with a large volume and a high doping concentration,showing a superiority in large-scale production,a feasibility of shape control and better mechanical properties. To achieve high-efficiency and high-power laser oscillation from sesquioxide ceramics,it is crucial to eliminate the main scattering centers inside microstructures,i.e.,residual pores and secondary phases.Raw powders with less agglomeration and high sinterability,combined with appropriate molding methods are fundamental for producing compacts with small pore size and uniform microstructures.This is favorable to avoid differentiate densification,degrading the optical homogeneity and transparency.During the sintering process,it is essential for pores to remain at grain boundaries until the final full densification.This prevents the formation of intragranular pores that are hard to remove.The effective control of grain boundary migration can be achieved to prevent pore-boundary separation through the addition of suitable sintering additives,regulation of sintering atmospheres(i.e.,vacuum,hydrogen and oxygen),and the use of advanced sintering techniques(i.e.,microwave sintering,spark plasma sintering or two-step sintering,etc.).In addition,pressure assisted sintering,including hot pressing and hot isostatic pressing can also improve the densification rate and facilitate the effective removal of residual pores.This even enables the full densification of sesquioxide ceramics without using sintering additives.Zirconia is once widely used as a sintering aid for sesquioxide transparent ceramics.However,it can severely degrade the laser performance of sesquioxide ceramics due to the occurrence of photodarkening phenomenon under high-power pump beam excitation.This may be attributed to the charge imbalance between Zr4+and host cation ions.Consequently,the introduced point defects act as acceptors for the electrons of excited laser ions,forming Zr3+color centers that cause a broad absorption in a wavelength range of 400-700 nm.This seriously affects the laser oscillation efficiency.Therefore,in addition to achieving laser-grade quality compared to single crystals,minimizing the use of sintering additives or regulating the lattice defects are also considered in the fabrication process of sesquioxide ceramics. In general,chemical co-precipitation process for synthesizing well-dispersed powders,combined with vacuum sintering and hot isostatic pressing sintering,is considered as an effective way for fabricating high-quality sesquioxide transparent ceramics.This approach provides a great driving force for densification through well controlling grain boundary diffusion and migration.However,it is necessary to determine suitable sintering curves and microstructure morphology before hot isostatic pressing. Summary and prospects:At present,solid-state lasers based on sesquioxide ceramics primarily emphasize the near-infrared wavelength range.These lasers can be categorized into applications near 1 μm(doped with Yb3+and Nd3+),2 μm(doped with Tm3+and Ho3+),as well as 1.6 μm and 3 μm(doped with Er3+),with significant achievements in both high power and ultra-short pulse laser outputs.It is noteworthy that Konoshima Chemical Co.and World-Lab Co.currently dominate the market with their high-quality sesquioxide laser ceramics.it is imperative to elucidate the effect of lattice defects on the laser performance in the future development of sesquioxide laser ceramics.Breakthroughs in fabrication technologies for large-size ceramics with a high optical homogeneity are crucial for laser engineering applications.Complex structure design is also essential to optimize thermal management in high-power laser systems.In addition,there should be also a focus on synthesizing single crystals through sintering methods,indicating a potential for obtaining new laser materials with heavily active ions doping and composite structures.A broad range of laser applications from sesquioxide transparent ceramics can be anticipated through the continuous improvement of powder synthesis,molding methods and sintering techniques.关键词
倍半氧化物/透明陶瓷/稀土离子/激光陶瓷/固体激光Key words
solid-state laser/sesquioxides/transparent ceramics/rare-earth ions/laser ceramics分类
化学化工引用本文复制引用
李晴,王俊,马杰,刘鹏,沈德元,章健,于浩海,张怀金,唐定远..倍半氧化物激光陶瓷的研究进展[J].硅酸盐学报,2024,52(3):1006-1022,17.基金项目
国家重点研发计划项目(2022YFB3605800) （2022YFB3605800）
国家自然科学基金项目(62105130,62075089) （62105130,62075089）
广东省科研能力提升计划项目(2022ZDJS116). （2022ZDJS116）
