放电等离子烧结制备高致密LiNbO_(3)陶瓷的研究

Preparation of High Density LiNbO_(3) Ceramics by Spark Plasma Sintering

为解决LiNbO_(3)粉体烧结活性低、高温下Li元素烧失导致的烧结体致密度低的问题,采用固相反应法合成化学计量比的LiNbO_(3)粉体,通过还原处理增加其氧空位浓度,然后采用放电等离子烧结(SPS)技术对其进行烧结,制备出高致密LiNbO_(3)陶瓷。利用XRD、EPR、XPS、Raman光谱仪、SEM对LiNbO_(3)粉体及其陶瓷进行表征和分析,结果表明,LiNbO_(3)粉体经700℃还原处理后氧空位浓度显著增大,且氧空位出现在Nb—O八面体中O原子的晶格位置。随着SPS温度的升高,LiNbO_(3)陶瓷的相对密度呈先增大后减小的趋势,900℃时烧结体的相对密度达到最大,为98.19%。经800℃退火增氧处理后,LiNbO_(3)陶瓷由黑色转变为白色,氧空位缺陷被消除,LiNbO_(3)陶瓷相对密度为98.32%。本研究为高致密碱金属铌酸盐陶瓷的制备提供了新思路。

In order to solve the problem of low sintering density caused by low sintering activity of LiNbO_(3) powders and loss on ignition of Li element at high temperature,LiNbO_(3) powders with stoichiometric ratio were synthesized by solid phase reaction method.The oxygen vacancy concentration of LiNbO_(3) powders increased by reduction treatment,and then high density LiNbO_(3) ceramics were prepared by spark plasma sintering(SPS) technology.The phase composition,oxygen vacancy concentration and surface morphology of LiNbO_(3) powders and the sintered body were characterized and analyzed by XRD,EPR,XPS,Raman spectroscopy and SEM.The results show that the oxygen vacancy concentration of LiNbO_(3) powders increases significantly after 700 ℃ reduction treatment,and the oxygen vacancies generate at the lattice position of O atom in Nb—O octahedron.With the increase of SPS temperature,the relative density of LiNbO_(3) ceramics shows a trend of increasing first and then decreasing.The relative density of sintered body reaches a maximum of 98.19% at 900 ℃.After annealing and oxygen increasing treatment at 800 ℃,the color of LiNbO_(3) ceramics changes from black to white.At the same time,the oxygen vacancy defect of LiNbO_(3) ceramics is eliminated and the relative density is 98.32%.This study provides a new idea for the preparation of high density alkali metal niobate ceramics.