Phase stability of Au-Li binary systems studied using neural network potential

K Shimizu and EF Arguelles and WW Li and Y Ando and E Minamitani and S Watanabe, PHYSICAL REVIEW B, 103, 094112 (2021).

DOI: 10.1103/PhysRevB.103.094112

The miscibility of Au and Li exhibits a potential application as an adhesion layer and electrode material in secondary batteries. Here, to explore alloying properties, we constructed a neural network potential (NNP) of Au-Li binary systems based on density functional theory (DFT) calculations. To accelerate construction of NNPs, we proposed an efficient and inexpensive method of structural dataset generation. The predictions by the constructed NNP on lattice parameters and phonon properties agree well with those obtained by DFT calculations. We also investigated the mixing energy of Au1-xLix with fine composition grids, showing excellent agreement with DFT verifications. We found the existence of various compositions with structures on and slightly above the convex hull, which can explain the lack of consensus on the Au-Li stable phases in previous studies. Moreover, we found other stable phases, namely Au0.45Li0.55, Au0.389Li0.611, and Au0.357Li0.643. Finally, we examined the alloying process starting from the phase separated structure to the complete mixing phase. We found that when multiple adjacent Au atoms dissolved into Li, the alloying of the entire Au/Li interface started from the dissolved region. This paper demonstrates the applicability of NNPs toward miscible phases, and it provides an understanding of the alloying mechanism.

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