Abstract Metastable ɛ-Co nanocrystals precipitate in silicate glass matrices together with stable β-Co nanocrystals at temperatures up to 873 K, whereas rapid thermal decomposition of e-Co is reported if formed by wet-chemical routes. Hence, high-temperature X-ray diffraction was used to determine the unknown coefficient of thermal expansion (CTE) of e-Co stabilized in glasses. The liquid character of the matrix provides free expansion of e-Co nanocrystals above the glass transition temperature (Tg), while a strain correction was performed for lattice constants below Tg using the co-precipitated β-Co as internal reference. It is found that CTE (298–873 K) of e-Co nanocrystals is 10.1 ppm K−1, which is slightly larger than CTE of β-Co nanocrystals (9.4 ppm K−1).

中文翻译：

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ε-Co 和 β-Co 纳米晶体在玻璃基质中的热膨胀

摘要 亚稳态 ɛ-Co 纳米晶体在高达 873 K 的温度下与稳定的 β-Co 纳米晶体一起沉淀在硅酸盐玻璃基质中，而据报道如果通过湿化学途径形成 e-Co 会快速热分解。因此，高温 X 射线衍射用于确定玻璃中稳定的 e-Co 的未知热膨胀系数 (CTE)。基质的液体特性提供了 e-Co 纳米晶体在玻璃化转变温度 (Tg) 以上的自由膨胀，同时使用共沉淀的 β-Co 作为内部参考对低于 Tg 的晶格常数进行了应变校正。发现e-Co纳米晶体的CTE（298-873 K）为10.1 ppm K-1，略大于β-Co纳米晶体的CTE（9.4 ppm K-1）。