Effects of pressure, nanoalloy size, and nanoalloy mole fraction on melting of Ir-Rh nanoalloys using molecular dynamics simulations

Abstract

We have simulated the melting points of the (Ir-Rh)N nanoalloys with N = 32, 108, and 256 and the different mole fractions (xIr = 0, 0.1, 0.3, 0.5, 0.7, 0.9, 1) at different exerted pressures. We have investigated the different effects such as the effects of the exerted pressure, nanoalloy molar fraction, and nanoalloy size on the melting and freezing behavior by employing Lindemann index (δ), enthalpy change (ΔHm), volume change (ΔVm), radial distribution function (RDF), and self-diffusion coefficient (D). Our results showed that the melting temperature of the nanoalloy increases as the external pressure increases. The melting point also increases with increasing the Ir mole fraction and the nanoalloy size. Our results also indicated that the enthalpy change of fusion decreases as the external pressure increases. Our results also showed that the ΔVm decreases with increasing the external pressure and the ΔVm for the smaller cluster is greater than the bigger cluster. Also, the ΔVm of the Ir-Rh nanocluster decreases with increasing the Ir mole fraction which is due to the greater Ir-Ir interaction than the Rh-Rh interaction. Our structural investigations showed that the nanoalloy RDF peak at higher pressure is much larger than same peak at lower pressure. The RDF peaks of the cluster also increases as the mole fraction of Ir increases. Our dynamical results indicated that the self-diffusion of the nanoclusters decrease with increasing the pressure and also with increasing the mole fraction of Ir.