X-Ray Diffraction and Electron Microscopy Studies of the Size Effects on Pressure-Induced Phase Transitions in CdS Nanocrystals
X-Ray Diffraction and Electron Microscopy Studies of the Size Effects on Pressure-Induced Phase Transitions in CdS Nanocrystals
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DOI：
10.1557/adv.2020.191
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发表时间：
2020-04
期刊：
影响因子：
0.8
通讯作者：
Lingyao Meng;H. Fan;J. Lane;Luke Baca;Jackie Tafoya;T. Ao;B. Stoltzfus;M. Knudson;D. Morgan;K. Austin;Changyong Park;Yang Qin
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文献类型：
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作者：
Lingyao Meng;H. Fan;J. Lane;Luke Baca;Jackie Tafoya;T. Ao;B. Stoltzfus;M. Knudson;D. Morgan;K. Austin;Changyong Park;Yang Qin
近年来，半导体纳米颗粒在高压下的相变行为研究因其在传感器、电子和光学等领域的潜在应用而受到越来越多的关注。然而，目前对纳米颗粒大小如何影响这种压力依赖特性的理解有些缺乏。特别是半导体CdS纳米颗粒在高压下的相行为尚未被广泛报道。因此，本文以不同尺寸的CdS纳米颗粒为模型体系，研究了粒径对高压诱导相变行为的影响。特别是，7.5、10.6和39.7 nm的球形CdS纳米颗粒被合成，并在金刚石砧细胞中受到高达15 GPa的高压控制。利用原位同步加速器广角x射线散射（WAXS）数据对这三种纳米颗粒进行分析表明，从纤锌矿到岩盐的相变发生在比块状材料更高的压力下。体积模量计算不仅表明纤锌矿CdS纳米材料比岩盐具有更强的可压缩性，而且表明CdS纳米材料的可压缩性取决于其颗粒大小。此外，在7.5 nm的CdS纳米颗粒中观察到球形纳米颗粒烧结成纳米棒。我们的研究结果为纳米颗粒在高压下的基本特性提供了新的见解，这将为新兴应用的新纳米材料结构的设计提供信息。
In recent years, investigations of the phase transition behavior of semiconducting nanoparticles under high pressure has attracted increasing attention due to their potential applications in sensors, electronics, and optics. However, current understanding of how the size of nanoparticles influences this pressure-dependent property is somewhat lacking. In particular, phase behaviors of semiconducting CdS nanoparticles under high pressure have not been extensively reported. Therefore, in this work, CdS nanoparticles of different sizes are used as a model system to investigate particle size effects on high-pressure-induced phase transition behaviors. In particular, 7.5, 10.6, and 39.7 nm spherical CdS nanoparticles are synthesized and subjected to controlled high pressures up to 15 GPa in a diamond anvil cell. Analysis of all three nanoparticles using in-situ synchrotron wide-angle X-ray scattering (WAXS) data shows that phase transitions from wurtzite to rocksalt occur at higher pressures than for bulk material. Bulk modulus calculations not only show that the wurtzite CdS nanomaterial is more compressible than rocksalt, but also that the compressibility of CdS nanoparticles depends on their particle size. Furthermore, sintering of spherical nanoparticles into nanorods was observed for the 7.5 nm CdS nanoparticles. Our results provide new insights into the fundamental properties of nanoparticles under high pressure that will inform designs of new nanomaterial structures for emerging applications.