热处理温度对掺钕钇铝石榴石陶瓷析晶的影响

采用氧化钕、氧化钇、硝酸铝、氨水以及柠檬酸作为原材料，以低温燃烧法(LCS)制备出纳米粉末材料。该方法解决了固相反应的高温合成及化学沉淀法的粉体团聚问题。通过热重-差热(TG-DTA)、X-射线粉末衍射(XRD)、傅里叶红外透射(FT-IR)和透射电镜(TEM)测试手段研究粉末的特性，采用谢莱方程(Scherrer)根据YAG(420)晶面的衍射曲线半峰宽数据计算出晶粒尺寸，详细研究陶瓷材料在不同热处理条件下的析晶情况。研究结果表明：YAG相的形成温度为850℃，在热处理过程中出现YAP中间相，于1050℃转变成纯YAG相，颗粒在不同的热处理条件下呈现不同的尺寸，在20～50nm范围变化。随着热处理温度的升高，平均晶粒尺寸增加，晶粒尺寸的标准偏差保持在2．0左右，晶格参数逐渐减小。晶粒主要以晶界扩散形式进行生长，晶格参数膨胀是由晶粒表面的排斥偶极距所造成的。

Effect of heat treatment on the crystallization of Nd:YAG ceramics

The(Y0.99Nd0.01)3Al5O12 nano-sized powders were synthesized by low temperature combustion (LCS), using Nd2O3, Y2O3, Al(NO3)3·9H2O, ammonia water and citric acid as starting materials. This method effectively solves the problems caused by solid-state reaction at high temperature and hard agglomerates brought by chemical precipitation method. The powders were characterized by TG-DTA, XRD,FT-IR and TEM, respectively. The crystallite sizes were calculated by Scherrer's formula using the full width at half maximum of YAG(420) diffraction lines. The study focused on the crystallization of ceramics with different heat treatment temperatures. The experiments show that the forming temperature of YAG crystal phase is 850 ℃ and YAP crystal phase appearing during the calcinations transforms to pure YAG at 1050 ℃. The particle size of the powders synthesized by LCS is in the range of 20～50 nm depending on the thermal treatment temperature. With the temperature increasing, the mean grain sizes ascend, the stand deviations keep at about 2.0 and crystal lattices decrease. The grains grows mainly by the grain boundary diffusion.The lattice parameter expansion is caused by an increase of repulsive dipolar interaction at the surface of particles.