超临界流体干燥技术制备Nd∶YAG纳米粉体及透明陶瓷

以Y₂O₃、OAl(NO₃)₃·9H₂O和Nd(NO₃)₃·6H₂O为原料，采用尿素均匀沉淀法制备不同Nd掺杂量的YAG前驱体沉淀，经CO₂ 超临界流体干燥得Nd:YAG前驱体，煅烧后得到Nd:YAG粉体；将粉体干压成型为素坯，经冷等静压后真空烧结获得性能良好的Nd:YAG透明陶瓷。用FT-IR、XRD、SEM等测试手段对Nd:YAG前驱体及粉体进行分析，并通过紫外-可见-近红外分光光度计、SEM测定表征了陶瓷样品的直线透过率及表面和断口形貌。结果表明，1300℃煅烧的Nd:YAG粉体均为纯YAG相，颗粒呈椭球形，分散性良好，尺寸分布均匀；粉体成型后在1780~1800℃真空烧结得到透明陶瓷，Nd摩尔分数为1%的YAG陶瓷样品晶粒尺寸分布为5~10μm，抛光后1064nm波长处直线透过率达80%。

Fabrication of neodymium doped yttrium aluminum garnet (Nd:YAG ) nanopowders and transparent ceramics by a supercritical fluid drying technique

Neodymium doped yttrium aluminum garnet (Nd:YAG) precursor precipitates doped with different amounts of Nd have been synthesized via the urea homogeneous precipitation method using Y₂O₃、OAl(NO₃)₃·9H₂O and Nd(NO₃)₃·6H₂O as raw materials. The fresh wet precipitates were dried by supercritical CO2 and then calcined at 1300℃ for 3h, affording Nd:YAG nanopowders. After uniaxially pressing into pellets followed by isostatic cold pressing, the resulting biscuits were sintered between 1780-1800℃ under vacuum giving transparent ceramics with excellent properties. The calcined powders were characterized by infrared (IR) spectroscopy, X-ray diffraction (XRD) and scanning electron microscopy. The transmittance of the transparent ceramics was measured using an ultraviolet visible near infrared spectrophotometer, and their surface topography was observed using a scanning electron microscope (SEM). The results showed that the precursor was directly converted to pure YAG after calcination at 1300℃ and that the particles were ellipsoidal with excellent dispersion and uniform size distribution. Transparent ceramics could obtained by sintering of the powders between 1780-1800℃ with 1% molar fraction of Nd, and the grain size distribution of the ceramic samples was 5-10μm, and the transmittance of double-polished samples with a thickness of 4mm was above 80% at a wavelength of 1064nm.