Effect of sintering temperature on crystal growth and evolution of CaZrTi2O7–CaNdTiNbO7 ceramics: Minor actinides immobilization host materials

IF 16.4 1区化学 Q1 CHEMISTRY, MULTIDISCIPLINARY

Accounts of Chemical Research Pub Date : 2024-10-14 DOI:10.1016/j.nucengdes.2024.113643

Shiyin Ji , Xiuhua Ji , Yanhao Song , Yanxia Wei , Tao Duan

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Abstract

Regulation of microstructure and processing cost of waste form are important for the design and application of high-level radioactive waste immobilization. In this study, CaZrTi₂O₇ (zirconolite) – CaNdTiNbO₇ (pyrochlore) ceramics were synthesized via conventional sintering method at 1000–1500 °C to investigate the effect of sintering temperature on the microstructure, solidification, and crystal evolution. The powder x-ray diffraction (XRD) and backscattered scanning electron microscopy–energy dispersive spectroscopy (BSEM–EDS) results indicated gradual formation of zirconolite and pyrochlore ceramics, following with their densification when increasing sintering temperature. It was found that sintering temperature should be higher than 1300 °C to form zirconolite-pyrochlore solid solutions. Densified pyrochlore was obtained at 1500 °C. In addition, transformation from relatively low-symmetry lattice to higher-symmetry lattice was found with an increase in sintering temperature. Furthermore, higher temperature can enhance the crystal growth and densification in the ceramic composite. The finding in this study could provide important suggestions to design and process zirconolite-pyrochlore waste forms for industrial application.

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烧结温度对 CaZrTi2O7-CaNdTiNbO7 陶瓷晶体生长和演化的影响小锕系元素固定化主材料

调节废物形态的微观结构和加工成本对于高放射性废物固定化的设计和应用非常重要。本研究采用传统烧结方法，在 1000-1500 ℃ 下合成了 CaZrTi2O7（锆英石）- CaNdTiNbO7（火成岩）陶瓷，研究了烧结温度对微观结构、凝固和晶体演化的影响。粉末 X 射线衍射（XRD）和背散射扫描电子显微镜-能量色散光谱（BSEM-EDS）结果表明，随着烧结温度的升高，锆英石和火成岩陶瓷逐渐形成，并逐渐致密化。研究发现，烧结温度应高于 1300 ℃，才能形成锆英石-绿柱石固溶体。在 1500 ℃ 时可获得致密化的热绿石。此外，还发现随着烧结温度的升高，相对低对称晶格向高对称晶格转变。此外，更高的温度还能促进陶瓷复合材料中晶体的生长和致密化。本研究的发现可为设计和加工工业应用的锆英石-钾长石废料形式提供重要建议。

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来源期刊

Accounts of Chemical Research 化学-化学综合

CiteScore

31.40

自引率

1.10%

发文量

312

审稿时长

2 months

期刊介绍： Accounts of Chemical Research presents short, concise and critical articles offering easy-to-read overviews of basic research and applications in all areas of chemistry and biochemistry. These short reviews focus on research from the author’s own laboratory and are designed to teach the reader about a research project. In addition, Accounts of Chemical Research publishes commentaries that give an informed opinion on a current research problem. Special Issues online are devoted to a single topic of unusual activity and significance. Accounts of Chemical Research replaces the traditional article abstract with an article "Conspectus." These entries synopsize the research affording the reader a closer look at the content and significance of an article. Through this provision of a more detailed description of the article contents, the Conspectus enhances the article's discoverability by search engines and the exposure for the research.