Size-dependent solid-solid phase transition process of Ag2S nanoparticles

• 作 者: Jun Liu Lu Chen Hangsheng Yang Ze Zhang Yong Wang
• 机 构: State Key Laboratory of Silicon Materials and Center of Electron Microscopy, School of Materials Sci
• 出 处: 自然科学进展（英文版）
• 发表日期: 2019年4期
• 关键词: Solid-solid phase transition Nanoparticles In-situ transmission electron microsc

It is well known that for a nanoparticle the solid-solid phase transition begins with the appearance of a high temperature disordered phase at the surface and the phase interface moves inward gradually with the increase of temperature.However,the size-dependent phase transition behavior remains unclear.Here we report an in-situ TEM study of the phase transition process of different-sized Ag2S nanoparticles at atomic resolution.The onset temperature of disordered phase of the small nanoparticle is found to be lower than that of the big nanoparticle.And,the disordered phase thickness of small nanoparticle is always thicker than that of big nanoparticle.By considering surface and interface free-energy,a phenomenological model based on the minimization of system free-energy is established,which could well explain our experimental results.These discoveries extend our understanding of size dependent phase transition mechanism.