Morphological change of Pd-based alloy nanoparticles observed by piezoelectric resonance method

Bimetallic nanoparticles exhibit unique properties that are distinct from those of their bulk and single-element nanoparticles, attracting the interest of researchers. Since these properties depend on their structure, the formation mechanism of alloy nanoparticles has been investigated. While simulations can predict preferred structure, experimentally fabricated nanoparticles often deviate. For example, for PdAu nanoparticles, an Au-shell/Pd-core structure is expected to be preferable, but Pd-shell/Au-core structures are also observed. Thus, there are discrepancies between predicted and experimentally observed structures, and the formation process and the preferred structure of the nanoparticles are not fully understood. This situation arises from the difficulty of real-time observation of the formation process. To solve this problem, we have developed a methodology that monitors the formation process by measuring the nanoparticle shape through the resonant vibration of a piezoelectric oscillator. This presentation will cover the developed method and our recent research results.