反应条件对均相沉淀法制备Nd:YAG粉体及透明陶瓷的影响

以A1(NO3).9H2O、Y2O3、Nd2O3、(NH)4SO4和尿素为原料,正硅酸乙酯为烧结助剂,采用均相沉淀法制备YAG纳米粉体,研究了反应温度、pH值和尿素的浓度对粉体的纯度及陶瓷透过率的影响。结果发现,在92℃,溶液的最终pH值为6左右,尿素的浓度为2M制备了分散均匀,团聚程度轻,晶粒尺寸为28nm的纯相粉体,经1785℃烧结后,制备的透明陶瓷在1064nm处的透过率为65.2%。     

顺序共沉淀法制备Nd:YAG陶瓷

以NH4Al(SO4)2·12H2O、Y2O3、Nd2O3为原料,NH4 HCO3为沉淀剂,采用顺序共沉淀法制备Nd:YAG粉体.并研究了碳酸氢铵浓度对粉体性能的影响,研究结果表明:较佳的碳酸氢铵浓度为1.0 mol/L.制得的粉体颗粒尺寸小,粒度分布窄,分散性好,具有良好的烧结活性,在1800℃真空烧结15 h制备了Nd:YAG透明陶瓷,其近红外波段的透过率为78％.断面和表面形貌显示陶瓷晶粒尺寸均匀,晶界清晰,结晶性好,瓷体致密,平均晶粒尺寸约为15 μm.     

Nd:YAG透明陶瓷及小型激光器研究

本文采用固相法和真空烧结技术制备了1at%Nd:YAG透明陶瓷,并以此为激光工作物质,设计制作了LD端面抽运小型激光器。当LD抽运功率为2W时,获得最高功率为1mW的532nm连续激光输出。     

共沉淀法合成Nd：YAG粉体及pH值的影响

以Y2O3、Al(NO3)3·9H2O和Nd(NO3)3为原料,碳酸氢氨为沉淀剂,均相共沉淀法制备Nd0.03Y2.97Al5O12(Nd:YAG)粉体.采用DSC/TG、XRD和TEM测试手段对粉末进行表征,研究pH值的影响.结果表明:pH值对合成粉体的成分和性能影响显著,当pH值为8.0时,前驱粉末在1 000℃热处理2 h后,全部转化成纯YAG相,粉体产生软团聚,主要为层状结构,并伴有小量纳米颗粒.     

溶胶-凝胶和冷冻干燥法制备Nd∶YAG纳米粉体及透明陶瓷的制备

本文以异丙醇铝,醋酸钇和醋酸钕为原料,用溶胶-凝胶和冷冻干燥法制备了Nd3+原子掺杂浓度为1.0％的Nd:YAG粉体.利用X-射线衍射仪和透射电镜对粉体的物相组成和粒度进行了分析测试,结果表明,前驱体经900℃高温煅烧2h后已完全转变为纯YAG相,平均粒径为40nm左右.随着煅烧温度的升高,粒径逐渐增大.采用热压和热等静压相结合工艺烧结出尺寸为φ50 mm ×2.5 mm的Nd∶YAG透明陶瓷,样品1064 nm的透过率为82.5％.     

均相沉淀法制备掺钕钇铝石榴石纳米粉末的研究

掺钕钇铝石榴石（Nd：YAG）多晶透明陶瓷具有容易制造、成本低、光学性能好、热导率高等优点,是一种很有前途的激光工作物质。以AI（N03）·9H2O,Y2O3,Nd2O3,（NH4）2SO4和尿素为原料,正硅酸乙酯为添加剂,采用均相沉淀法制备出分散均匀、纯YAG立方晶相的Nd：YAG纳米前驱体粉末。采用XRD、FT-IR、TEM等测试手段对前驱体粉末进行表征。研究结果表明：Nd：YAG前驱体粉末在800℃时为无定型态,当温度达到890℃时析出大量的中间相YAlO3（Y=AP）和少量的Y3Al5O5（YAG）,当温度达到1000℃时就全部转化为YAG立方晶相。     

Yb:YAG陶瓷纳米粉体的研究

本文采用化学均相共沉淀法,以Y(NO3)3.6H2O、Al(NO3)3.9H2O和Yb(NO3)3.5H2O为原料,尿素作为沉淀剂,聚乙二醇400为表面活性剂,制备了Yb:YAG陶瓷纳米粉体。利用扫描电镜、X射线衍射对纳米陶瓷粉体的形貌、物相结构进行了分析。结果表明:化学反应过程中添加一定量的表面活性剂,能获得尺寸均匀、分散性好、无明显团聚的纳米粉体。     

国内外透明激光陶瓷的研究现状

透明激光陶瓷是一种具有战略意义的新型激光工作物质。与单晶相比,多晶透明激光陶瓷制备周期短、生产成本低、可以大批量生产,而且易获得大尺寸、掺杂浓度高、光学均匀性好的样品。综述了近年来透明激光陶瓷的研究进展,对透明激光陶瓷的制备技术和透光性的影响因素进行了阐述,并对其应用前景进行了展望。     

钇铝石榴石激光透明陶瓷纳米粉体的研究

本试验以硝酸钇、硝酸铝和硝酸钕为原料,碳酸氢铵为沉淀剂,聚乙二醇（PEG400）及硫酸铵为分散剂,采用共沉淀方法制备了Nd：Y3Al5O12（Nd：YAG）,研究了分散剂的种类及盐溶液初始溶度对粉体性能的影响。并采用X射线衍射仪、扫描电镜等对YAG粉体进行了表征分析。实验结果表明,合成的YAG粉体均为立方晶系石榴石型结构。当以PEG为分散剂时,所得粉体颗粒度小、分散均匀、粒径在50nm左右,且随着盐溶液初始浓度的增加,YAG颗粒粒径减小。     

离子浓度和分散剂对合成Nd:YAG粉体晶相的影响

以碳酸氢铵为沉淀剂,共沉淀合成了Nd:YAG陶瓷粉体。分析了合成过程中盐溶液离子浓度和分散剂含量对粉体后期晶相转变的影响。研究结果表明盐溶液浓度在0.16 mol·L^-1和0.32 mol·L^-1时,煅烧过程中粉体出现Y₂O₃、YAM等过渡晶相,这些过渡相需要在更高的温度才能完全转化为纯YAG晶相。当盐溶液浓度降低到0.08 mol·L^-1, pH调节到8.0时,各组分离子和掺杂离子达到分子水平的均匀混合,合成粉体煅烧过程中直接转化为YAG晶相。添加的分散剂 对Al₂O₃和Y₂O₃扩散反应生成YAG晶相有一定的阻碍作用。采用纯相的Nd:YAG粉体制备的多晶透明陶瓷获得了1.6W的激光输出。     

Hot Isostatic Pressing of Transparent Nd:YAG Ceramics

This paper demonstrates that fine-grained (2–3 μm), transparent Nd:YAG can be achieved at SiO₂ doping levels as low as 0.02 wt% by the sinter plus hot isostatic pressing (HIP) approach. Fine grain size is assured by sintering to 98% density, in order to limit grain growth, followed by HIP. Unlike dry-pressed samples, tape-cast samples were free of large, agglomerate-related pores after sintering, and thus high transparency (i.e., >80% transmission at 1064 nm) could be achieved by HIP at <1750°C along with lower silica levels, thereby avoiding conditions shown to cause exaggerated grain growth. Grain growth was substantially limited at lower SiO₂ levels because silica is soluble in the YAG lattice up to ∼0.02–0.1 wt% at 1750°C, thus allowing sintering and grain growth to occur by solid-state diffusional processes. In contrast, liquid phase enhanced densification and grain growth occur at ∼0.08–0.14 wt% SiO₂, especially at higher temperatures, because the SiO₂ solubility limit is exceeded.     

Laminar-Structured YAG/Nd:YAG/YAG Transparent Ceramics for Solid-State Lasers

A laminar-structured YAG/1.0 at.% Nd:YAG/YAG transparent ceramic was fabricated by a solid-state reaction method and vacuum sintering using high-purity α-Al₂O₃, Y₂O₃, and Nd₂O₃ as raw materials with tetraethoxysilane as a sintering aid. The microstructure, the optical property, and the laser performance of the ceramic composite prepared were investigated in this paper. It is found that the sample exhibits a pore-free structure and the average grain size is about 15 μm. There is no secondary phase both at the grain boundary and at the grain matrix. The optical transmittance of the sample (5.0 mm thick) is 80.2% at 1064 nm. The lasing sample is Φ16.2 mm × 5.0 mm in size, mirror polished on both sides and without a coating. A laser diode (808 nm) was used as a pump source with a maximum output of about 1000 mW, and the end-pumped laser experiment was demonstrated. With 658 mW of maximum absorbed pump power, a laser output of 8 mW has been obtained with a slope efficiency of 4.0%.     

Agglomeration Control of Nd:YAG Nanoparticles Via Freeze Drying for Transparent Nd:YAG Ceramics

Neodymium-doped yttrium aluminum garnet (Nd:YAG) nanopowders were synthesized by the carbonate coprecipitation method. The effects of freeze drying and conventional oven drying of the precursor on the agglomeration of the Nd:YAG nanopowders were compared. The optical properties of the Nd:YAG nanopowders and the corresponding sintered Nd:YAG transparent ceramics were also investigated. The Nd:YAG nanopowders synthesized from freeze-dried precursor showed better dispersion and narrower particle size distribution compared with the powders synthesized from conventional oven drying. As a result, the Nd:YAG nanopowders synthesized from freeze-dried precursor have good sinterability, and Nd:YAG transparent ceramics were fabricated by vacuum sintering at 1750°C for 5 h.     

Solid-State Reactive Sintering of Transparent Polycrystalline Nd:YAG Ceramics

Transparent polycrystalline Nd:YAG ceramics were fabricated by solid-state reactive sintering a mixture of commercial Al₂O₃, Y₂O₃, and Nd₂O₃ powders. The powders were mixed in methanol and doped with 0.5 wt% tetraethoxysilane (TEOS), dried, and pressed. Pressed samples were sintered from 1700° to 1850°C in vacuum without calcination. Transparent fully dense samples with average grain sizes of ∼50 μm were obtained at 1800°C for all Nd₂O₃ levels studied (0, 1, 3, and 5 at.%). The sintering temperature was little affected by Nd concentration, but SiO₂ doping lowered the sintering temperature by ∼100°C. Abnormal grain growth was frequently observed in samples sintered at 1850°C. The Nd concentration was determined by energy-dispersive spectroscopy to be uniform throughout the samples. The in-line transmittance was >80% in the 350–900 nm range regardless of the Nd concentration. The best 1 at.% Nd:YAG ceramics (2 mm thick) achieved 84% transmittance, which is equivalent to 0.9 at.% Nd:YAG single crystals grown by the Czochralski method.     

直接干压成型与真空烧结技术制备Nd:YAG透明陶瓷

以高纯氧化物粉体为原料,采用直接干压成型与固相反应烧结技术制备Nd:YAG透明陶瓷,并对其光学透过率和烧结致密化行为进行了研究。结果表明,经1 760℃烧结10 h后,250 MPa成型压力下的样品透过率最高,在1 064 nm处达到83.8%。其素坯的气孔率为40.5%,气孔平均孔径74.5 nm。烧结后陶瓷的显微结构致密,晶界干净清晰,断裂方式为沿晶断裂。将250 MPa成型压力下获得的陶瓷素坯在不同温度和时间下烧结,得到致密化轨迹、晶粒生长曲线以及显微结构演变等信息。通过理论拟合,得出低温下陶瓷致密化和晶粒生长的控制机制为晶界扩散。     

Transparent Nd:YAG Ceramics Fabricated Using Nanosized γ-Alumina and Yttria Powders

Neodymium (Nd):Y₃Al₅O₁₂ (YAG) ceramics of excellent transparency have been fabricated by solid-reactive sintering, using nanosized γ-Al₂O₃ and Y₂O₃ powders as the starting materials. Reaction sequences and sintering behaviors of the powder mixture were characterized by X-ray diffractometry and dilatometry. One feature of the solid reactions involving γ-Al₂O₃ is the occurrence of hexagonal YAlO₃, which is unstable and transforms to perovskite YAlO₃ (YAP) upon further heating. Because of the high reactivities of the starting nanopowders, a complete conversion of the powder mixture to YAG has been achieved by heating at 1300°C for 4 h, via Y₄Al₂O₉, hexagonal YAlO₃, and YAP phases. In-line transmittances of the 1.5 at.% Nd:YAG ceramics (doped with 0.5 wt% of tetraethyl orthosilicate) at 700 nm are 81.0% and 65.7% after vacuum sintering at 1700° and 1600°C for 5 h, respectively.     

Fabrication of Polycrystal line, Transparent YAG Ceramics by a Solid-State Reaction Method

Polycrystalline, transparent YAG (Y₃AI₅O₁₂) ceramics were fabricated by a solid-state reaction method using high-purity Al₂O₃ and Y₂O₃ powders. The mixed powder compacts were sintered at 1600° to 1850°C for 5 h under vacuum. Optical transmittance in the region between the ultraviolet and infrared wavelengths for YAG ceramics (1 mm thick) sintered at 1800°C was similar to that for a YAG single crystal.     

采用两步烧结方法制得的非化学配比镁铝尖晶石透明陶瓷的透光性能研究

本文报道了以MgO·nAl2O3超细粉体为原料,采用真空烧结和热等静压结合的两步烧结技术制备了4种不同化学配比的镁铝尖晶石透明陶瓷,并对其红外和可见波段光学通过率进行了测试分析.结果表明:n=1.3和1.5的非配比透明陶瓷在紫外-可见波段和红外波段与化学配比透明陶瓷一样具有较高的光学透过率,而n=1.8的陶瓷的透过率则有较大程度的下降.