Anisotropic Temperature-Driven Strain Dynamics in VO2 Solid-State Microactuators
Anisotropic Temperature-Driven Strain Dynamics in VO2 Solid-State Microactuators
复制标题
VO2 固态微执行器中的各向异性温度驱动应变动力学
DOI：
10.1021/acsaelm.0c00776
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发表时间：
2020
影响因子：
4.7
通讯作者：
Marre Daniele
中科院分区：
文献类型：
--
作者：
Manca Nicola;Kanki Teruo;Endo Fumiya;Ragucci Enrico;Pellegrino Luca;Marre Daniele
由于二氧化钒的相变特点是大的晶格变化和高的能量密度，因此它是一种特别吸引人的材料，用于开发固态微纳米驱动器。它的马氏体相变具有强烈的各向异性：加热时，轴收缩近1%，而轴和轴分别膨胀约0.5%和0.4%。这是开发基于VO2的驱动方案时要考虑的一个关键方面，因为使用多晶VO2和平均机制可能会降低器件的性能。这项工作通过表征具有不同晶体微结构的薄膜，即单晶和“镶嵌”结构，对VO2在相变过程中的内置应变进行了定量分析。提出了一种定量测量外延薄膜中沿不同晶格方向的固有应变的通用方法。该方法基于沿不同晶格方向排列的双夹持微桥的光学轮廓术。我们的结果表明，VO2器件的应变动力学和各向异性可以由VO2的晶体结构控制。此外，我们还论证了机械自由度对VO2微机械系统输运性质的影响。
VO2is a particularly appealing material for the development of solid-state micro- and nanoactuators due to its phase transition characterized by a large lattice change associated with a high energy density. Its martensitic transformation is strongly anisotropic: upon heating thecaxis contracts by almost 1%, while theaandbaxes expand by about 0.5 and 0.4%, respectively. This is a crucial aspect to consider when developing VO2-based actuating schemes, as the employment of polycrystalline VO2and averaging mechanisms may reduce device performances. This work provides a quantitative analysis of the built-in strain in VO2across its phase transition by characterizing thin films having different crystalline microstructures, namely single-crystal and “tessellated” ones. A general method to quantitatively measure the built-in strain along different lattice directions in epitaxial thin films is presented. This method is based on optical profilometry of double-clamped microbridges aligned along different lattice directions. Our results show that the strain dynamics and anisotropy of VO2devices can be controlled by the VO2crystalline microstructure. Moreover, we demonstrate that the mechanical degrees of freedom affect the transport properties in VO2micromechanical systems.