Extended Unit Cell\nModel Employing Two Vectors for\nCrystal Structure Analysis in IrPd Nanoparticles for Catalysis

Crystal\nstructure is closely related to the function\nof materials,\nand understanding of crystal structure is essential not only in the\nscientific field but also in the industrial field for applications\nof materials. We introduce the extended unit cell (EUC) model with\ntwo vectors to effectively represent complex nanoparticle structures\nsuch as twinning and multiple twinning. This model overcomes the limitations\nof conventional single- and two-phase analyses in capturing such structures.\nFurthermore, the local atomic distribution in Ir–Pd bimetallic\nNPs was investigated in detail, and it was found that Ir and Pd are\nat sites represented by a single vector while suggesting the localized\npresence of Ir at sites where the vector changes. Such a detailed\nobservation of local atomic distribution is difficult to represent\nby conventional two-phase analysis, highlighting the great advantage\nof our proposed EUC model. This study not only aims to enhance the\nunderstanding of nanoparticle structures and their properties for\ncatalysis but also proposes a methodology that significantly reduces\ncomputational costs by simplifying the representation of complex structures.\nIt is particularly suitable for catalytic applications requiring precise\nstructural control.