Tian Li-Yun, Eriksson Olle, Vitos Levente
Applied Materials Physics, Department of Materials Science and Engineering, Royal Institute of Technology, 100 44, Stockholm, Sweden.
Division of Materials Theory, Department of Physics and Astronomy, Uppsala University, Box 516, 751 20, Uppsala, Sweden.
Sci Rep. 2020 Sep 8;10(1):14766. doi: 10.1038/s41598-020-71551-4.
The ordered phase of the FeNi system is known for its promising magnetic properties that make it a first-class rare-earth free permanent magnet. Mapping out the parameter space controlling the order-disorder transformation is an important step towards finding growth conditions that stabilize the [Formula: see text] phase of FeNi. In this work, we study the magnetic properties and chemical order-disorder transformation in FeNi as a function of lattice expansion by utilizing ab initio alloy theory. The largest volume expansion considered here is 29% which corresponds to a pressure of [Formula: see text] GPa. The thermodynamic and magnetic calculations are formulated in terms of a long-range order parameter, which is subsequently used to find the ordering temperature as a function of pressure. We show that negative pressure promotes ordering, meaning that synthetic routes involving an increase of the volume of FeNi are expected to expand the stability field of the [Formula: see text] phase.
FeNi体系的有序相以其具有前景的磁性能而闻名，这使其成为一流的无稀土永磁体。描绘出控制有序-无序转变的参数空间是找到稳定FeNi [公式：见正文] 相生长条件的重要一步。在这项工作中，我们利用第一性原理合金理论研究了FeNi中磁性能和化学有序-无序转变随晶格膨胀的变化。这里考虑的最大体积膨胀为29%，这对应于 [公式：见正文] GPa的压力。热力学和磁学计算是根据长程序参数来进行的，该参数随后被用于确定作为压力函数的有序温度。我们表明负压促进有序化，这意味着涉及FeNi体积增加的合成路线有望扩大 [公式：见正文] 相的稳定域。
