Structure patterns of one-step synthesis of CuNi nanopowders in air environment: Experiment and atomistic simulations

Abstract

A possibility for one-step synthesis of bimetallic CuNi nanopowders in a different ratio of Ni to Cu by solution combustion synthesis technique under normal air atmosphere without any post reduction is reported. The effect of different types of fuels like citric acid and glycine on the combustion process and characteristics of resultant solid products were investigated. XRD results showed the existing of CuNi as a main phase and small amounts of CuO and (Ni,Cu)₄N. Determined CuNi particle sizes were in the range of up to 50 nm. Computer simulation was performed using the molecular dynamics method for similar concentration compositions, but in size range of 4.5–5.5 nm, as a result of cooling the system from 1700 K to 300 K. In addition, two types of melting scenario of binary CuNi NPs were studied: 1) heterogeneous melting of monocrystalline Cu and Ni NPs; 2) melting of the crystallization products of binary NPs. Melting temperatures weakly depend on the choice of the above-mentioned melting scenario. However, the nature of subsequent crystallization can be influenced by the initial energy of the system, which is higher for case 1. The characteristic temperatures of phase transitions of melting and crystallization are determined based on the analysis of hysteresis loops of the specific potential part of the internal energy of NPs. The patterns of atomic and structural segregation in binary CuNi NPs were studied.