【作者】 刘奋照；

【导师】 杨儒；

【作者基本信息】 北京化工大学 ， 材料科学与工程， 2010， 硕士

【摘要】 本论文对Nd:YAG纳米粉体及透明陶瓷的发展和制备方法作了综述,并介绍了超临界干燥技术的发展和应用。本论文以硝酸铝、硝酸钇、硝酸钕为原料,分别以碳酸氢铵和尿素为沉淀剂,化学沉淀法结合CO2超临界流体干燥技术合成一系列钕掺杂的钇铝石榴石前驱体粉末,并在不同温度下煅烧得到Nd:YAG样品。采用XRD、FT-IR、TG/DTA、SEM、BET和荧光分光光度计等测试手段对前驱体及煅烧产物进行表征。结果表明,采用碳酸氢铵共沉淀法结合CO2超临界干燥制备的1%Nd:YAG前驱体,比表面积为271.64m2·g-1,XRD结果表明前驱体为晶态，1100℃空气中煅烧2h后出现YAG晶相,同时夹杂Y2O3和YAM相,1400℃煅烧2h后仍未得到纯YAG。尿素均匀沉淀法制备的前驱体为非晶态氢氧化物和碳酸盐混合物,常规干燥法得到的前驱体比表面积较小,且发生严重团聚,1000℃煅烧得到纯Nd:YAG,颗粒粒径分布不均匀、分散性较差,团聚严重。与常规干燥法结果比较,CO2超临界干燥明显改善了常规干燥时发生的严重团聚问题,使前驱体粉末具有良好的分散性、较高的比表面积及烧结活性,800℃煅烧后直接生成纯YAG相,未出现中间相,1000℃煅烧后粉体仍能保持良好的分散性,颗粒呈类球形状,尺寸分布于35-45nm之间。不同钕掺杂量前驱体的晶化产物均为YAG相,没有出现中间相。其晶胞参数随钕掺杂量的增大而变大,2e值则随钕掺杂量的增大而变小。荧光光谱分析表明Nd:YAG粉体的荧光发射光谱和激发光谱的相对发光强度均随煅烧温度升高而增强,随钕掺杂量的增加呈先增大后减小的变化趋势,掺杂量为0.8%时发光强度最大。更多还原

【Abstract】 In this paper, We briefly illustrated the development and synthesis methods of Nd:YAG nanopowders and transparent ceramics. In addition, the development and application of supercritical drying technology were also introduced.In this paper, aluminum nitrate, yttrium nitrate, neodymium nitrate as raw materials, ammonium bicarbonate and urea as precipitation, respectively, a series of neodymium-doped yttrium aluminum garnet precursor powders were synthesized by chemical precipitation method combined with CO2 supercritical fluid drying, and calcined at different temperatures. The precursor and calcined products were characterized by XRD, FT-IR, TG/DTA, SEM, BET and fluorescence spectrophotometer test. The results showed that 1% Nd:YAG precursor powders were synthesized by ammonium bicarbonate co-precipitation combined with CO2 supercritical fluid drying, the specific surface area was 271.64m2·g-1. XRD results showed that the precursor powders were crystalline, YAG generated at 1100℃in air for 2h, including Y2O3 and YAM. When calcined temperature was 1400℃, pure YAG was not still obtained. The precursor powders which synthesized by urea homogeneous precipitation combined with conventional drying method composed of mixtures of amorphous hydroxide and carbonate, the specific surface area are small and serious agglomeration, after calcined at 1000℃in air for 2h, pure Nd:YAG were obtained, but the size distribution of particles was uneven, the dispersity were poor and agglomerate seriously. Compared with conventional drying method, CO2 supercritical fluid drying improved serious agglomeration that appeared in conventional drying method, so the precursor powders had good dispersion and high specific surface area and sintering activity. CO2 supercritical fluid drying samples which calcined at 800℃could be directly generated single YAG crystal phase, and intermediate phase did not appear. The powders which calcined at 1000℃still maintain a good dispersion, and particles were spherical shape, size distribution was between 35-45nm. In addition, the samples with different Nd doped were crystalline YAG phase, no intermediate phase. The cell parameters increased with the amount of Nd doping, but 20 decreased with the Nd increasing. The fluorescence spectra showed that the emission spectra and excitation spectra intensity increased with the rising of the sintering temperature, but it increased before the Nd-doped content 0.8%, and then descend with the increase of Nd-doped content.更多还原