Thermodynamic Analysis of Multiply Twinned Particles: Surface Stress Effects

Abstract

In nanoparticle technologies, such as SERS, fuel cell catalysis and data storage, icosahedral and decahedral nanoparticles, owing to their defect structure, provide higher functionality than their single-crystal Wulff counterparts. However, precise control on the yield of multiply twinned structures during solution synthesis has been challenging. In particular, it is difficult to synthesize icosahedral structures due to the high volumetric strain energy associated with the disclination defects and the transition to decahedral morphologies. In this Letter, we elucidate the role of surface stresses in influencing the thermodynamic stability of multiply twinned particles. Increasing the surface stresses inhibits the formation of decahedral structures and increases the likelihood of synthesizing metastable icosahedral particles. Analogously, large decahedral particles may be stabilized by decreasing the surface stresses. Therefore, by tailoring the solution chemistry to influence the surface stresses, greater control over the synthesis of multiply twinned structures can be achieved. SECTION: Physical Processes in Nanomaterials and Nanostructures

Understanding the Stability of Pt‐Based Nanocages under Thermal Stress Using In Situ Electron Microscopy

“…We believe that this transformation process is driven largely by thermodynamic constraints, and can be explained using an energetic consideration . For the formation of a nanoframe from a nanocage upon heating while supported on a substrate, the total free energy (ΔG total ) driving the process can generally be defined as the sum of the following two major contributions, the surface free energy (ϵ surface ) and the volumetric free energy (ϵ volume ) [Eq.…”

On the habitus modification of silver microcrystals by electrolityc origin

“…At the range of nano-and microscale small particles and microcrystals often demonstrate nontrivial features. In particular, decahedral or icosahedral morphology is documented for small particles for materials with FCC crystal structure [2][3][4][5][6]. Such particles are referred to as pentagonal small particles (PSPs).…”

“…Neighbor tetrahedra are joined on {111}-type crystallographic planes, which become twin boundaries inside PSPs. It is due to this fact such objects are also designated as multiple-twinned particles [2][3][4][5][6].Small metal particles including multiple-twinned ones can be fabricated by various techniques, in particular, by nucleation from a gas phase with the use of physical or chemical vapor deposition onto a substrate [1]. Electrodeposition from an electrolyte solution plays an important role among the methods of fabrication of metal microparticles.…”

“…Neighbor tetrahedra are joined on {111}-type crystallographic planes, which become twin boundaries inside PSPs. It is due to this fact such objects are also designated as multiple-twinned particles [2][3][4][5][6].…”

“…Within the framework of the approach originally proposed by Marks in Refs. [3,4,13,14], modified Wulff construction [15] can be utilized to derive theoretical shapes for multiple-twinned particles [13]. It was shown that the incorporation of twin boundary energies for faceted particles led to a number of constrained local minima in the total energy of PSPs in addition to the minimum corresponding to a single crystal Wulff polyhedron [13].…”