(10g) Development of a Bond-Centric Model for Thermodynamic Stability of Nanoalloys

Authors: 
Taylor, M. G., University of Pittsburgh
Yan, Z., University of Pittsburgh
Mascareno, A., University of Pittsburgh
Mpourmpakis, G., University of Pittsburgh
Metal nanoparticles find application today in a breadth of technologies, from optical devices to catalysis. However, understanding of nanoparticle stability remains somewhat limited in terms of nanoparticle morphology (size/shape) and chemical ordering (e.g. in nanoalloys). Toward understanding nanoparticle stability, first principles methods such as Density Functional Theory (DFT) are widely used and known to be accurate, but are limited to small nanoparticle sizes (<2nm in diameter) due to their high computational cost. Here, we present an accelerated bond-centric (BC) model we developed and tested against DFT calculations. [1] We highlight that this new BC model captures both cohesive and excess energy trends over a range of mono- and bi-metallic nanoparticles. Importantly, because the developed BC model utilizes only tabulated data (diatomic bond energies and bulk cohesive energies) along with structural information of the nanoparticles (coordination numbers), it can be used to rapidly screen both crystalline and amorphous structures. Namely, we apply our new BC model to amorphous CuZr nanoparticles and a recently-reported 23,196-atom FePt nanoalloy [2] and ~10^5 of its homotops with both ordered and disordered regions, finding agreement both with the DFT (CuZr) and experimental (FePt) results. This work therefore holds the potential to significantly accelerate nanoalloy design.

[1] Z. Yan, M. G. Taylor, A. Mascareno, G. Mpourmpakis, Size-, Shape-, and Composition-Dependent Model for Metal Nanoparticle Stability Prediction. Nano Letters 18, 2696-2704 (2018).

[2] Y. S. Yang et al., Deciphering chemical order/disorder and material properties at the single-atom level. Nature 542, 75-79 (2017).