锆基烧绿石Nd2Zr2O7固化锕系核素钍

doi:10.15541/jim20140240

无机材料学报 ›› 2015, Vol. 30 ›› Issue (1): 81-86.DOI: 10.15541/jim20140240 CSTR: 32189.14.10.15541/jim20140240

锆基烧绿石Nd₂Zr₂O₇固化锕系核素钍

王烈林, 谢华, 陈青云, 王茜, 龙勇, 邓超, 张可心

(西南科技大学核废物与环境安全国防重点学科实验室, 绵阳 621010)

收稿日期:2014-05-07 修回日期:2014-07-01 出版日期:2015-01-20 网络出版日期:2014-12-29
基金资助:
国家自然科学基金青年基金(21101129);四川省教育厅自然科学基础研究项目(14ZA0103);核废物与环境安全国防重点科学实验室开放基金(11zxnk08, 13zxnk09)

Synthesis and Characterization of Thorium-doped Nd₂Zr₂O₇ Pyrochlore

WANG Lie-Lin, XIE Hua, CHEN Qing-Yun, WANG Qian, LONG Yong, DENG Chao, ZHANG Ke-Xin

(Fundamental Science on Nuclear Wastes and Environmental Safety Laboratory, Southwest University of Science and Technology, Mianyang 621010, China)

Received:2014-05-07 Revised:2014-07-01 Published:2015-01-20 Online:2014-12-29
Supported by:
National Natural Science Foundation of China (21101129);Natural Science Foundation Research Project of Education Department of Sichuan Province (14ZA0103);Open Project of Fundamental Science on Nuclear Wastes and Environmental Safety Laboratory(11zxnk08, 13zxnk09)

摘要/Abstract

摘要：

A₂Zr₂O₇锆基烧绿石因优异的辐照和化学稳定性能成为高放废物固化的理想基材。以硝酸锆、硝酸钕、硝酸钍作为原料, 通过柠檬酸络合方法, 在1200℃保温12 h成功制备了含20at%钍的Nd_1.8Th_0.2Zr₂O_7.1烧绿石固化体。产物采用X射线粉末衍射、扫描电镜、红外光谱以及拉曼光谱表征。结果表明: Th替代Nd进入A₂Zr₂O₇的A位, Nd_1.8Th_0.2Zr₂O_7.1固化体保持单一的烧绿石结构; Th⁴⁺的离子半径小于Nd³⁺, 导致固化体晶格常数减小; 通过Scherrer公式计算和SEM观察, 样品平均粒径为50 nm左右; 制备的固化体致密度高。随着Th成分的增加, Nd_1.8Th_0.2Zr₂O_7.1固化体烧绿石结构的无序化程度增加。

关键词: 锆基烧绿石, 烧绿石结构, Nd1.8Th0.2Zr2O7.1, 结构无序化

Abstract:

A₂Zr₂O₇ zirconate pyrochlores are proposed as potential host phases for the immobilization of high level nuclear waste because of their chemical and radiation stabilities. Thorium-doped pyrochlore Nd_1.8Th_0.2Zr₂O_7.1was synthesized at 1200℃ for 12 h by citrate polymer precursor method using zirconium nitrate, thorium nitrate, neodymium nitrate and citrate acid as raw materials. The phase compositions of the products were characterized by XRD, SEM, FT-IR and Raman spectrum. The results reveal that neodymium ions are substituted by thorium ions at the A position of A₂Zr₂O₇, which maintain the single pyrochlore structure. The lattice parameter decreases for Nd₂Zr₂O₇pyrochlore with the addition of 20at% Th because the effective ionic radius of Th⁴⁺ is less than that of Nd³⁺. The mean grain sizes of these samples are about 50 nm and the bulk densities are more than 95% of theoretical values. With thorium content increase, the degree of structural disorder in Nd_1.8Th_0.2Zr₂O_7.1pyrochlore increases.

Key words: zirconate pyrochlore, pyrochlore structure, Nd1.8Th0.2Zr2O7.1, structural disorder

中图分类号:

O731
TL93

王烈林, 谢华, 陈青云, 王茜, 龙勇, 邓超, 张可心. 锆基烧绿石Nd₂Zr₂O₇固化锕系核素钍[J]. 无机材料学报, 2015, 30(1): 81-86.

WANG Lie-Lin, XIE Hua, CHEN Qing-Yun, WANG Qian, LONG Yong, DENG Chao, ZHANG Ke-Xin. Synthesis and Characterization of Thorium-doped Nd₂Zr₂O₇ Pyrochlore[J]. Journal of Inorganic Materials, 2015, 30(1): 81-86.

图/表 7

图 1 Nd1.8Th0.2Zr2O7.1前驱体及在不同烧结条件下产物的XRD图谱

Fig. 1 XRD patterns of precursor powder and Nd1.8Th0.2Zr2O7.1 samples sintered at different conditions. Rhombns indicate the superstructure peaks

表 1 不同烧结条件下产物的晶粒尺寸和晶格常数

Table 1 Lattice parameters and crystallite sizes of samples prepared at different conditions

Composition	Calcination condition	Crystal size/nm	Lattice parameter/nm
Nd₂Zr₂O₇	1200℃/12 h	45.8	1.0674
Nd_1.8Th_0.2Zr₂O_7.1	Precursor	9.3	-
Nd_1.8Th_0.2Zr₂O_7.1	1000℃/6 h	9.5	-
Nd_1.8Th_0.2Zr₂O_7.1	1200℃/6 h	15.9	-
Nd_1.8Th_0.2Zr₂O_7.1	1200℃/12 h	45.4	1.0634

图 2 Nd1.8Th0.2Zr2O7.1和Nd2Zr2O7在1200℃/12 h烧结条件下产物的XRD图谱

Fig. 2 XRD patterns of Nd1.8Th0.2Zr2O7.1 and Nd2Zr2O7 samples sintered at 1200℃ for 12 h. (Rhombns indicate superstructure peaks)

图 3 Nd1.8Th0.2Zr2O7.1和Nd2Zr2O7在1200℃/12 h条件下烧结产物的Raman光谱

Fig. 3 Raman spectra of Nd1.8Th0.2Zr2O7.1 and Nd2Zr2O7 samples sintered at 1200℃ for 12 h

图 4 Nd1.8Th0.2Zr2O7.1(a, b, c, d)和Nd2Zr2O7(e)在不同条件下烧结产物的FT-IR图谱

Fig. 4 FT-IR spectra of Nd1.8Th0.2Zr2O7.1 (a, b, c, d) and Nd2Zr2O7 (e) samples sintered at different conditions

图 5 Nd2Zr2O7(a)和Nd1.8Th0.2Zr2O7.1(b)样品的SEM和EDS分析结果

Fig. 5 SEM images and EDS analyses of Nd2Zr2O7 (a) and Nd1.8Th0.2Zr2O7.1(b) samples sintered at 1200℃ for 12 h

图 6 Nd1.8Th0.2Zr2O7.1样品的元素分布图(a)与背散射电子像(b)

Fig. 6 Elements distribution image (a) and backscattered electron micrograph (b) of Nd1.8Th0.2Zr2O7.1. Red is Zr; Green is Nd; Blue is Th

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锆基烧绿石Nd₂Zr₂O₇固化锕系核素钍

Synthesis and Characterization of Thorium-doped Nd₂Zr₂O₇ Pyrochlore

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