Department of Applied Physics, Xi'an Jiaotong University , Xi'an 710049, China.
ACS Appl Mater Interfaces. 2017 Apr 12;9(14):12486-12493. doi: 10.1021/acsami.7b01337. Epub 2017 Mar 31.
Pt-Co bimetallic nanoparticles are promising candidates for Pt-based nanocatalysts and magnetic-storage materials. By using molecular dynamics simulations, we here present a detailed examination on the thermal stabilities of Pt-Co bimetallic nanoparticles with three configurations including chemically disordered alloy, ordered intermetallics, and core-shell structures. It has been revealed that ordered intermetallic nanoparticles possess better structural and thermal stability than disordered alloyed ones for both PtCo and PtCo systems, and PtCo-Pt core-shell nanoparticles exhibit the highest melting points and the best thermal stability among Pt-Co bimetallic nanoparticles, although their meltings all initiate at the surface and evolve inward with increasing temperatures. In contrast, Co-Pt core-shell nanoparticles display the worst thermal stability compared with the aforementioned nanoparticles. Furthermore, their melting initiates in the core and extends outward surface, showing a typical two-stage melting mode. The solid-solid phase transition is discovered in Co core before its melting. This work demonstrates the importance of composition distribution to tuning the properties of binary nanoparticles.
Pt-Co 双金属纳米颗粒是 Pt 基纳米催化剂和磁性存储材料的有前途的候选材料。通过使用分子动力学模拟，我们在这里详细研究了三种构型的 Pt-Co 双金属纳米颗粒的热稳定性，包括化学无序合金、有序金属间化合物和核壳结构。结果表明，对于 PtCo 和 PtCo 体系，有序金属间化合物纳米颗粒比无序合金具有更好的结构和热稳定性，而 PtCo-Pt 核壳纳米颗粒在 Pt-Co 双金属纳米颗粒中表现出最高的熔点和最好的热稳定性，尽管它们的熔化都是从表面开始并随着温度的升高向内发展。相比之下，与上述纳米颗粒相比，Co-Pt 核壳纳米颗粒的热稳定性最差。此外，它们的熔化始于核心并向外表面扩展，表现出典型的两阶段熔化模式。在 Co 核心熔化之前，发现了 Co 核心的固-固相变。这项工作表明了组成分布对调节二元纳米颗粒性能的重要性。
