Application of Stereology on Neodymium-Doped Yttrium Aluminum Garnet (Nd∶YAG) Transparent Ceramics

Neodymium-doped yttriumaluminumgarnet (Nd∶YAG) transparent polycrystalline ceramics have theadvantages of good chemical stability ,high doped-ionconcentration ,excellent optical performance ,and hightemperature stability[1 ,2].Toi mprove the transmittanceof Nd∶YAGceramics ,most of the researches focus onthe precursor powders synthesis and on ceramic sinter-ing. However , quantification of ceramic microstruc-ture can aid in developing useful correlation betweenprocessing conditions andthe …     

Application of Stereology on Neodymium-Doped Yttrium Aluminum Garnet （Nd： YAG） Transparent Ceramics

Nd ： YAG precursor powders were synthesized by homogeneous precipitation, and Nd ： YAG transparent ceramics were prepared by vacuum sintering at 1700 ℃ for 5 h. The ceramic materials were characterized by light transmittance and field emission gun-environment scanning microscope. Using statistics and stereology theory, study was carried out on the quantitative relationships between light transmittance and stereological parameters in three-dimensional Euclidean space. It is found that the transmittance of Nd：YAG with 1 mm in thickness is about 45% and 58% in visible and near-infrared wavelength, respectively. The transmittance linearly increases with increasing equivalent sphere diameter and reaches the theoretical value of single crystal when the equivalent sphere diameter is 20μm. The transmittance decreases with the increasing of mean specific area per unit volume of grain and discrete grains, and the transmittance decreases with increasing mean free distance of grains in Nd：YAG ceramics.     

驱动电压对纳米结构Ni_xO_y薄膜电致变色性能的影响

采用掠射角直流反应磁控溅射法制备了膜厚约480 nm的NixOy薄膜。利用场发射扫描电子显微镜和能谱仪对NixOy薄膜的表面和断面形貌及化学组成进行了表征;利用电化学工作站和紫外分光光度计对NixOy薄膜进行了不同驱动电压下循环伏安特性、光学调制幅度、光密度变化以及致色效率的测试;通过改变扫描速度,经线性拟合后计算得到离子扩散速率;从计时电流曲线,获得薄膜致/褪色响应时间。研究表明,80°掠射角溅射沉积的NixOy薄膜表面形貌疏松多孔,断面为斜柱状结构,为离子与电子的注入/抽出提供了较大的比表面积;NixOy薄膜的电化学容量和离子扩散速率在±1.2 V驱动电压下得到了显著提高,从而使薄膜展现出优良的光调制幅度和致色效率。同时,薄膜还表现出良好的循环稳定性和快速响应的特性。     

均相共沉淀法合成钇铝石榴石(YAG)纳米粉末的研究

透明YAG多晶陶瓷具有容易制造、成本低、尺寸大、掺杂浓度高、热导率高、耐热冲击性好、可大批量生产、易实现多层和多功能的陶瓷结构等优点,使得它作为激光介质而成为单晶的强有力的替代者.本实验以Y2O3、Al(NO3)3*9H2O、(NH4)2SO4为原料,尿素为沉淀剂,正硅酸乙酯作为添加剂,采用均相共沉淀法制备出YAG前驱体粉末,在沉淀过程中采用静电稳定、聚合物空间位阻以及共沸方法相结合有效地防止了纳米颗粒硬团聚的形成,YAG前驱体颗粒尺寸小于50nm,并对反应过程中pH值的变化进行研究.采用DTA/TG、IR、 XRD和TEM测试手段对粉末材料进行了表征,根据Scherrer公式计算出晶粒大小,研究了晶粒尺寸分布及其变化情况.研究结果表明:前驱体粉末经过1 200℃温度烧结后,全部转化YAG相,其晶粒尺寸小于50nm,随着烧结温度升高,晶粒平均尺寸增大.