Journal of Inorganic Materials ›› 2022, Vol. 37 ›› Issue (10): 1073-1078.DOI: 10.15541/jim20220077

Special Issue: 【结构材料】核用陶瓷

• RESEARCH ARTICLE • Previous Articles     Next Articles

Structural Evolution and Chemical Durability of Thorium-incorporated Nd2Zr2O7 Pyrochlore at A and B Sites

WANG Lielin(), XIE Hua, XIE Yuqi, HU Pingtao, YIN Wen, REN Xinyue, DING Yun   

  1. Fundamental Science on Nuclear Wastes and Environmental Safety Laboratory, Southwest University of Science and Technology, Mianyang 621010, China
  • Received:2022-02-16 Revised:2022-03-23 Published:2022-10-20 Online:2022-04-07
  • About author:WANG Lielin (1982-), male, PhD, associate professor. E-mail:
  • Supported by:
    National Natural Science Foundation of China(21101129);National Natural Science Foundation of China(41502028);Natural Science Foundation of Sichuan Province(2018jy0449);Natural Science Foundation of Sichuan Province(2022NSFSC0252)


A2B2O7 pyrochlore is considered as a candidate host matrix for high-level radioactive wastes due to its incorporation and physicochemical stability. Nd1.8Th0.2Zr2O7 and Nd2Zr1.8Th0.2O7 pyrochlore samples doped with 20% thorium (in molar) were successfully prepared by using spray-pyrolysis and high temperature sintering method. The structures of the synthesized immobilization were characterized, and the chemical durability tests were investigated by the MCC-1 method. Structural analyses show that samples Nd1.8Th0.2Zr2O7 and Nd2Zr1.8Th0.2O7 exhibit pure single pyrochlore structure. Rietveld refinement analyses show that the value of 48f oxygen site parameter of 20% thorium-doped Nd2Zr2O7 pyrochlore increases, which suggests that the structure is transforming from ordered pyrochlore to disordered structure, as compared with Nd2Zr2O7. The Nd1.8Th0.2Zr2O7 pyrochlore structure evolution results from the distortion of the AO8 hexahedral structure, while the B-site substitution leads to partial deformation of the BO6 octahedron. The leaching experiment results show that the normalized leaching rate of thorium is as low as 10-5g·m-2·d-1 after 42 d. Thorium can be well incorporated at the A and B cation sites of the Nd2Zr2O7 pyrochlore structure of which the immobilization exhibits the excellent physical and chemical properties.

Key words: pyrochlore, thorium, structural evolution, chemical durability, A-site substitution, B-site substitution

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