Operating interfaces to synthesize L1₀-FePt@Bi-rich nanoparticles by modifying the heating process

A facile strategy to operate interfaces when synthesizing L1₀-FePt@Bi-rich nanoparticles (NPs) has been proposed. Two interfaces are indispensable to obtain the high ordering L1₀-FePt structure. One is the mismatched interfaces between the initial γ-PtBi₂ nuclei and the disordered fcc-FePt phase. The other is the in situ grown coherent interfaces between the L1₀-FePt and Bi-rich phases. Increasing the heating rates when the temperature rises from 120 °C to 310 °C benefits the formation of mismatched interfaces and improves the uniformity of phases and composition in NPs. Reducing the heating rate at higher temperature ensures sufficient time for Bi to diffuse across the coherent interface, which facilitates the disorder-order transition of L1₀-FePt NPs. This study provides a new perspective on operating interfaces during the wet-chemical synthesis process.