Direct Observation of Curved Surface Enhanced Disordering in Ag₂S Nanoparticles

Abstract

Surface induced order–disorder phase transition has been widely studied on flat bulk surfaces, while such a transition is poorly understood on curved surfaces in nanoscale. Here, we report a direct observation of the dynamic behaviors of surface-initiated disordering in Ag2S nanoparticles using atomic resolution in situ transmission electron microscopy. It was found that the disordering behavior is different from the traditional model that the disordered layer follows a logarithmic thickness dependence with temperature. In particular, the disordering is largely enhanced at higher temperature when the radius of the residual order phase is getting smaller. Moreover, the correlation length of disordered phase was found to be several times larger than the typical value for bulk surfaces. This significantly enhanced disordering in nanoparticles could be attributed to the extra driving force provided by the decreasing of order–disorder interface area.

Ag-Ion Dynamics in the Low-Temperature Form of Ag2S as Studied by Impedance Spectroscopy

“…Disorder of a special crystal face before the order–disorder phase transition has been observed by Liu et al using in situ TEM in β-Ag 2 S nanoparticles . Our XRD profiles at different temperatures also show that the diffraction peaks of the (100) plane gradually decrease with increasing temperature and finally disappear.…”

“…Recently, in situ TEM revealed an order−disorder phase transition induced by the disordered crystal face in the surface region of β-Ag 2 S nanoparticles at a lower temperature than that of the order−disorder transition of the bulk. 36 Impedance spectroscopy (IS) has been proved to be an effective probe into the ionic dynamics of ionic and superionic conductors. This work reports the first application of this technique to Ag 2 S. From the temperature dependence of the loss of complex permittivity at different frequencies, we observe four relaxation peaks, ordered as P 1 , P 2 , P 3 , and P 4 from low to high temperature.…”

Recent Progresses on Structural Reconstruction of Nanosized Metal Catalysts via Controlled-Atmosphere Transmission Electron Microscopy: A Review

“… The phase stability of catalyst NPs is also related to the temperature. With the temperature change, the bulk phase or surface structure will undergo reconstruction. − The adsorption/desorption of a gas on the surface of the metal catalyst can be greatly affected by the temperature change of the system. Gas adsorption can directly alter the surface energy of the catalyst system and drive the reconstruction. − Many chemical processes are triggered by the energy provided by heating.…”

“…The phase stability of catalyst NPs is also related to the temperature. With the temperature change, the bulk phase or surface structure will undergo reconstruction. − …”

Ductile‐Metal Ag as Buffer Layer for Flexible Self‐Powered Ag2S Photodetectors

“…As for the inorganic compound materials, the surface mainly consists with some vacancy and disordering defects. [ 13 ] These defects result in less efficient bonding between the inorganic compound materials and the substrate, so that the inorganic thin films can be easily peeled off from that, featuring relative poor flexibility. To fabricate highly flexible inorganic semiconductor thin films, it is of great challenge to enhance the adhesion between the inorganic compound semiconductor thin films and the flexible substrate.…”