原位加热诱导Nb扩散引起Nb0.8CoSb有序度的转变
Nb0.8CoSb ordering transformation caused by in situ heating-induced Nb diffusion
李其柱 1范浩涵 1高梓恒 2南鹏飞 1朱铁军 2葛炳辉1
作者信息
- 1. 安徽大学物质科学与信息技术研究院,信息材料与智能感知安徽省实验室,合肥 230601
- 2. 浙江大学材料科学与工程学院,硅及先进半导体材料全国重点实验室,杭州 310027
- 折叠
摘要
本文以覆盖Nb薄膜的半赫斯勒合金Nb0.8CoSb为研究对象,成功利用原位加热透射电镜技术在高温下诱导Nb扩散,致使Nb0.8CoSb转变为有序度更高的Nb0.8+δCoSb,即倒空间漫散带代表的短程有序结构转变为超结构衍射点代表的长程有序结构.进一步的分析表明,这种超结构的调制波矢为q=(a∗+b∗-c∗)/3,其形成主要源自于Sb和Nb组分的变化.与离位合成的Nb0.84CoSb的微观结构进行对比,发现二者中超结构不同,这种超结构的调制波矢为 q=(2a∗-2c∗)/3,主要源自于Nb组分的变化.此项研究揭示了组分导致超结构的多样性以及半赫斯勒合金结构相变的复杂性,丰富了对半赫斯勒合金材料的理解,对相变材料的设计以及功能调控具有重要指导意义.
Abstract
This study focuses on the investigation of Nb0.8CoSb half-Heusler alloy covered with Nb films.By employing in-situ heating transmission electron microscopy(TEM)technique,diffusion of Nb is observed at high temperature,showing the ordering transformation from Nb0.8CoSb to Nb0.8+δCoSb.Through observations of high-angle annular dark-field(HAADF)images and selected-area electron diffraction(SAED)patterns,it is found that under elevated temperatures,the diffuse streaks representing short-range disorder in Nb0.8CoSb sample transform into superlattice diffraction spots representing long-range order.The modulation wave vector of this superstructure is determined to be q=1/3(a∗+b∗-c∗).This structural evolution primarily arises from the diffusion of Nb atoms from the Nb film into the Nb0.8CoSb sample at high temperature,leading to compositional changes in Sb and Nb.Further comparative analysis reveals significant differences between in-situ synthesized Nb0.8+δCoSb samples and ex-situ synthesized Nb0.84CoSb samples despite both exhibiting superstructures.In the ex-situ synthesized Nb0.84CoSb,the modulation wave vector of the superstructure is q=1/3(2a∗-2c∗),which is mainly attributed to Nb compositional variations.Moreover,the superstructure in Nb0.84CoSb sample can remain stable from room temperature to high temperature,whereas in Nb0.8+δCoSb samples,it only exists at elevated temperatures and gradually weakens as the temperature decreases,suggesting that it may be a metastable structure between Nb0.8CoSb and Nb0.84CoSb.This study reveals the diversity of superstruc-tures induced by compositional variations and the complexity of structural phase transitions in half-Heusler alloys,enriching the understanding of these materials and providing important guidance for the design and functional control of phase-change materials.
关键词
固态相变/原位加热/短程有序/半赫斯勒合金Key words
solid-state phase transition/in-situ heating/short-range ordering/half-Heusler alloy引用本文复制引用
基金项目
国家自然科学基金(11874394)
国家自然科学基金(92163203)
出版年
2024
国家科技期刊平台
NSTL
万方数据