中文摘要：

系统地研究了pH值对沉淀法制备弛豫铁电体PSN粉末的相结构，化学组成和晶粒形貌的影响。实验发现，以NH4OH作为沉淀剂，随着pH值从2增至12，金属离子按Nb，Sc，和Pb的顺序先后沉淀；当pH达到8—10时，3种元素的沉淀率均达到99％以上。此外，在不同的温度下煅烧沉淀粉体发现，pH超过8时得到的粉体都经历了从焦绿石变为纯钙钛矿相的转变过程；相反，在低pH值下得到的粉体一直存在一定的焦绿石相。而且，随着pH的上升，晶粒形貌从200nm的球状变为1μm的片状。pH值为8时沉淀得到的粉体，经800℃煅烧，得到符合化学计量比的Pb（Sc1/2Nb1/2）O3粉末，由此烧结得到的陶瓷表现出良好的弛豫铁电性。

英文摘要：

The effects of pH value of the precipitating solutions on the phase structure, chemical components, and grain morphologies of PSN powders were investigated. It is found that the metal ions ofNb, Sc, and Pb will orderly precipitate with the increased pH value from 2 to 12 when using NH4OH as the precipitant. When the pH value reached 8-10, the precipitation rates of all the three elements are over 99%. Moreover the powders, which precipitated with pH value higher than 8, will undergo the crystal phase transition from pyrochlore to pure perovskite when calcined at different temperatures. On the contrary, the powders preparing at the relative lower pH value always have a certain quantities of pyrochlore phase. The grain morphology altered from 200 nm ball-like to 1 μm sheet-like with the increased pH value. Relaxor ferroelectric lead scandium niobate （Pb（Sc1/2Nb1/2）O3）, which presents a composition near to the chemical stoichiometry, has been gained after 800 ℃ calcination of the precipitates at a mild precipitation condition of pH value around 8. And the dielectric behaviors of PSN ceramics exhibit typical relaxor ferroelectrics characteristics.