Epitaxial growth and stress relaxation of vapor-deposited Fe–Pd magnetic shape memory films
Epitaxial growth and stress relaxation of vapor-deposited Fe–Pd magnetic shape memory films
复制标题
气相沉积 Fe-Pd 磁性形状记忆薄膜的外延生长和应力松弛
DOI：
10.1088/1367-2630/11/11/113054
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发表时间：
2009
影响因子：
3.3
通讯作者：
S. G. Mayr
中科院分区：
文献类型：
--
作者：
L. Kühnemund;T. Edler;I. Kock;M. Seibt;S. G. Mayr
为了在微尺度磁性形状记忆致动器件中实现最大性能，需要几百纳米厚的外延膜。通过电子束蒸发在热MgO衬底（500 °C及以上）上生长外延膜。通过高分辨率透射电子显微镜、原位衬底曲率测量和经典分子动力学（MD）模拟研究了薄膜的结构特性和应力松弛机制。Vollmer-Weber生长过程中引入的高失配应力在开始时被部分或完全位错松弛，这取决于衬底温度。这种弛豫允许避免应力诱导的外延击穿，并且没有发现外延的厚度限制。对于690 °C或更高的衬底温度，膜在fcc奥氏体相中生长。在此温度以下，形成铁沉淀。MD模拟显示了这些沉淀物如何影响部分位错的运动，从而可以解释在实验中观察到的这些薄膜在生长的初始阶段的较高的应力水平。
To achieve maximum performance in microscale magnetic shape memory actuation devices epitaxial films several hundred nanometers thick are needed. Epitaxial films were grown on hot MgO substrates (500 °C and above) by e-beam evaporation. Structural properties and stress relaxation mechanisms were investigated by high-resolution transmission electron microscopy, in situ substrate curvature measurements and classical molecular dynamics (MD) simulations. The high misfit stress incorporated during Vollmer–Weber growth at the beginning was relaxed by partial or perfect dislocations depending on the substrate temperature. This relaxation allowed the avoidance of a stress-induced breakdown of epitaxy and no thickness limit for epitaxy was found. For substrate temperatures of 690 °C or above, the films grew in the fcc austenite phase. Below this temperature, iron precipitates were formed. MD simulations showed how these precipitates influence the movements of partial dislocations, and can thereby explain the higher stress level observed in the experiments in the initial stage of growth for these films.