Temperature- and Size-Dependent Compositionally Tuned Microstructural Landscape for Ag-46 Atom % Cu Nanoalloy Prepared by Laser Ablation in Liquid

Abstract

We report a temperature- and size-dependent compositionally tuned microstructural landscape for Ag-46 atom % Cu alloy nanoparticles. The microstructural and morphological changes were established through the technique of in situ transmission electron microscopy. The nanoparticles were synthesized by laser ablation of alloy target in an aqueous medium. The as-synthesized particles predominantly contain nanosized grains of a single-phase solid solution with grains having sizes ∼3 ± 0.5 nm. For particles with smaller sizes (∼20 nm), the solid solution decomposes and grains coarsen on heating to yield predominantly bicrystals containing two phases of Ag-rich and Cu-rich solid solution. The microstructure of the larger particles (≥40 nm) evolves through segregation of Ag and their preferential growth near the surface of the particles. This leads to a core–shell-like composition distribution at a certain range of temperatures (≥200 °C) and sizes (≥32 nm). At higher temperatures, these core–shell particles undergo a morphological transition through grain growth yielding bicrystals of two phases. We present a size- and temperature-dependent morphology diagram that captures these changes.

Antimicrobial Properties of the Ag, Cu Nanoparticle System

“…In an approximate sense, a mixture of Ag and Cu bimetallic NPs, with a nanograin microstructure, can be considered a single-phase nanoalloy ( Figure 11 a), whereas, in other microstructures, such as in Figure 11 b,c, the Ag and Cu atoms do not distribute uniformly. It was found that homogenous AgCu nanoalloys ( Figure 11 a) gradually separate phases ( Figure 11 b–d), as the temperature is increased [ 254 ]. In addition to the influence of temperature, the morphologies of the Cu-rich α phase and the Ag-rich β phase can change with an increase of Cu content, passing from separated phases to nanograins to core-shell microstructures ( Figure 12 a–d), since the microsystems tend to keep the α-β interphase surface energy minimum [ 237 , 255 ].…”

“… ( a ) Single-phase AgCu solid solution; ( b ) core-shell structure of AgCu nanoalloys; ( c ) structure of Ag and Cu in both phases; ( d ) biphasic. Reproduced with permission from Reference [ 254 ]. Copyright 2016, American Chemical Society.…”

Competition of Core-Shell and Janus Morphology in Bimetallic Nanoparticles: Insights From a Phase-Field Model

“…During continued heating, the NPs eventually coarsened to several hundred nanometers in size through coalescence. In contrast, when Cu-Ag NPs of near-equiatomic composition produced by pulsed laser deposition 19 were exposed to temperatures up to 600 °C, the initially homogeneous solid solution phase decomposed to form Ag-and Cu-rich phases. Figure 1, which is reproduced from this work 19 , shows that particles below ∼20 nm in size developed into a Janus configuration, while the larger ones (size ∼40 nm) exhibited an Ag@Cu CS morphology.…”

“…Thus, bulk thermodynamics favors phase separation in the NPs and suppresses formation of homogeneous alloyed phase. However, capillary forces come into dominance at small sizes, and depending on the composition, size, and method of preparation, NPs are sometimes found in the homogeneous alloyed state as well 17,19,20 .…”

A Study on the Annealing Ambient Effect on the Anti-Pollution Characteristics of Functional Film for PV Modules

“…On the other hand, a hydrophilic coating removes dust by spreading water on the surface instead of forming water droplets on the surface. This method allows water droplets to spread between pollutants and the substrate surface, thereby removing the pollutants to be attached to the substrate and letting them flow with water droplets [12][13][14][15][16]. The water-soluble polymer materials TiO 2 and silica are known to have excellent hydrophilicity [17].…”