Structural and magnetic properties of SmCo5−XNiX intermetallic compounds

Highlights: • Ab initio computational investigation is achieved to evaluate the magnetization and the structure stability of SmCo_5−xNi_x . • Collinear and noncollinear calculations are performed using two different sets of U parameters under the DFT+U approach. • The analysis concluded the set of U parameters 4.70 for Sm and 2.22 for Co and Ni is the most reliable set for SmCo_5−xNi_x. • Energetically favourable models as well as the configurations with the highest magnetization are identified and analysed. • Experimental implementation for the SmCo₄Ni is presented to translate the findings from simulations to bulk materials. • The energetically favourable atomistic configuration does not exhibit in many cases the maximum magnetization. • The deviation from the energetically favourable, highly symmetric unit cell leads to models with maximum magnetization. -- Abstract: Modern technological applications in an extensive variety of fields require the use of Permanent Magnets (PMs). Intermetallic compounds such as SmCo₅ are already used as high-performance PMs. Reducing the high content of the expensive cobalt in SmCo₅ from low-priced transition metals can lead in a cost reduction. This study examines by computational methods the effect of substituting cobalt atoms in the crystal structure of SmCo₅ by nickel atoms. The aim is to specify the structure that will be stable and at the same time will maintain high values of magnetization. A series of atomistic simulations are implemented based on Density Functional Theory calculations. Various simulations are performed by considering all possible crystallographic positions of Co and Ni atoms in a SmCo_5−xNi_x compound. Based on energy minimization and maximizing the magnetization we pinpointed the interesting cases. An experimental implementation based on the sample with x = 1 is presented to translate the findings from atomistic simulations to realizable bulk materials. Interestingly, it is concluded that in many cases an energetically favourable atomistic configuration does not exhibit maximum magnetization. It should be noted that for the experimentally investigated case of SmCo₄Ni, both the energetically favourable as well as the magnetically maximum configuration have been identified.