湿化学法制备Y_2O_3纳米粉及透明陶瓷

Solution-based Processing of Y_2O_3 Nanopowders Yielding Transparent Ceramics

以Y(NO3)3溶液和NH3·H2O为原料,制备了Y2O3纳米粉体.先驱沉淀物的化学组成为Y2(OH)5NO3·H2O．研究了pH值及滴加过程对先驱沉淀物形貌及Y2O3产物烧结性的影响．正向滴定,pH值较低时(pH=7．9),先驱沉淀物为片状结构;pH值较高时(pH=10．0),先驱沉淀物片层状结构特性减轻,并且颗粒变的细小．反向滴加时,片层状结构特征消失,主要为块状晶粒．先驱沉淀物为片状结构时,得到的粉体活性较高．添加适量的(NH4)2SO4能够减轻Y2O3粉体的团聚,沉淀的同时控制pH值在9以下,所得到的粉体具有更好的烧结性能．采用得到的Y2O3纳米粉,不加入任何烧结助剂,经1700℃真空烧结4h得到了透明Y2O3陶瓷。

Nanocrystalline yttria powders were synthesized from Y（NO3）3 solution and ammonia water by a precipitation method. The chemical composition of the hydroxide precursor was Y2（OH）5NO3.H2O. The effects of pH values and striking process on the properties of hydroxide precursor and resultant yttria powders were studied. At low pH conditions （pH=7.9） of the normal striking method, the precipitation precursor has a layered structure. If the final pH value is comparatively high （pH=10.0）, the layered nature of the precipitation precursor decreases, and the crystallites are more fine. By using reverse-strike technique, the layered nature of the flocs disappears, and it is mainly composed of more equiaxed crystallites. More sinterable yttria powders can be synthesized by calcining the hydroxide precursor with platelet-shaped structure. A small amount of ammonium sulfate doping can reduce the agglomeration of the resultant yttria powders. Resultant Y2O3 powders synthesized at a low pH （below 9） show much better sinterability than those from higher pH value derived precursor. By using the nanocrystalline yttria powder, transparent yttria ceramics were produced by vacuum sintering at 1700℃ for 4h without any additives.