烧结温度和钙含量对CaNdTiNbO_(7)型陶瓷固化体晶相结构的影响  

Effect of Sintered Temperature and Ca Content on the Crystal Structure of CaNdTiNbO_(7)-type Ceramic

作　　者：许保亮[1,2,3,4] 黄建秋 吴俊翔 吉诗银 熊鹰 段涛[2,3,4] XU Baoliang;HUANG Jianqiu;WU Junxiang;JI Shiyin;XIONG Ying;DUAN Tao(School of Materials and Chemistry,Southwest University of Science and Technology,Mianyang 621010,Sichuan,China;State Key Laboratory of Environment-friendly Energy Materials,Southwest University of Science and Technology,Mianyang 621010,Sichuan,China;National Co-innovation Center for Nuclear Waste Disposal and Environmental Safety,Southwest University of Science and Technology,Mianyang 621010,Sichuan,China;Tianfu Institute of Research and Innovation,Southwest University of Science and Technology,Chengdu 610299,Sichuan,China)

机构地区：[1]西南科技大学材料与化学学院,四川绵阳621010 [2]西南科技大学环境友好能源材料国家重点实验室,四川绵阳621010 [3]西南科技大学核废物与环境安全省部共建协同创新中心,四川绵阳621010 [4]西南科大四川天府新区创新研究院,成都610299

出　　处：《西南科技大学学报》2023年第2期9-15,21,共8页Journal of Southwest University of Science and Technology

基　　金：国家自然科学基金(12105235,22176157,U2167221);四川省科技计划项目(2021JDTD0019);西南科技大学博士基金(20zx7146)。

摘　　要：萤石及其衍生结构陶瓷是高放废物固化的潜在基体材料,针对烧绿石型高放废物固化体CaNdTiNbO_(7)存在缺陷萤石相和钙钛矿杂相问题,设计了一系列温度与Ca含量效应实验,通过传统高温固相法在1000~1600℃下合成CaNdTiNbO_(7)固化体样品,并在1400℃合成Ca_(0.99)NdTiNbO_(6.99)和Ca_(0.9)NdTiNbO_(6.9)陶瓷,通过XRD和SEM-EDS研究烧结温度与钙含量对合成CaNdTiNbO_(7)型纯相烧绿石固化体的影响。结果表明:随着烧结温度增加,固化体次生萤石相发生227型缺陷萤石向215型缺陷萤石相再到烧绿石结构的转变,在1500℃以上合成近似单相的烧绿石样品,而不能去除钙钛矿杂相。降低Ca的含量可以实现钙钛矿杂相的去除,但会生成227型缺陷萤石而非215型缺陷萤石相。CaNdTiNbO_(7)型烧绿石固化体合成温度应不低于1500℃且应适当减少钙元素的含量。Fluorite and its derived structural ceramics are potential matrix materials for the immobilization of high-level radioactive wastes(HLW).In view of the problem of defective fluorite phase and perovskite impurity phase in the sintered chlorite-type HLW curing body CaNdNbO_(7),a series of experiments were designed on the effect of temperature and Ca content to synthesize CaNdTiNbO_(7)solidified samples by conventional high-temperature solid phase method at 1000-1600℃,and Ca_(0.99)NdTiNbO_(6.99)and Ca_(0.9)NdTiNbO_(6.9)ceramics were synthesized at 1400℃.The effect of sintered temperature and Ca content on the synthesis of CaNdTiNbO_(7)-type pure-phase pyrochlore solids were investigated by XRD and SEM-EDS.The results show that with the increase of sintering temperature,the secondary fluorite phase of the solidified body undergoes a transformation from 227-type defective fluorite phase to 215-type defective fluorite phase,and then to pyrochlore structure,and the near single-phase pyrochlore samples are synthesized above 1500℃without removing the perovskite impurity phase.Perovskite can be eliminated through decreasing the Ca content,but it will generate 227-type defective fluorite phase instead of 215-type defective fluorite phase.Therefore,the synthesis temperature of CaNdTiNbO_(7)type pyrochlore ceramic should not be lower than 1500℃and the content of Ca should be appropriately reduced.

关 键 词：萤石衍生结构 温度效应 Ca含量效应 烧绿石 陶瓷固化体 

分 类 号：O614.33[理学—无机化学]