Atomistic study on the pressure dependence of the melting point of NdFe12

C Skelland,R W Chantrell,A Kato,G Hrkac,G Zimanyi,T Shoji,R F L Evans,T Schrefl,M Winklhofer,J Fischbacher,M Ito,S C Westmoreland,T Ostler,M Yano

doi:10.1063/1.5130450

Abstract

We investigated, using molecular dynamics, how pressure affects the melting point of the recently theorised and epitaxially grown structure NdFe12. We modified Morse potentials using experimental constants and a genetic algorithm code, before running two-phase solid-liquid coexistence simulations of NdFe12 at various temperatures and pressures. The refitting of the Morse potentials allowed us to significantly improve the accuracy in predicting the melting temperature of the constituent elements.

Highlights

The transition to green energy relies on the improvement of two areas of technology, the harnessing of energy from natural sources, and the application of that energy
The curie temperature is of particular importance for electrical engines in cars, which are prone to heating up to a temperature significant enough to decrease the magnetisation of the magnets and lower the efficiency of the engine
In high performance electrical engines Nd2Fe14B is the magnet of choice with some of the neodymium replaced with dysprosium to increase curie temperature giving (Nd, Dy)2Fe14B.1

Summary

Introduction

The transition to green energy relies on the improvement of two areas of technology, the harnessing of energy from natural sources, and the application of that energy. In both cases electrical engines have a significant role to play, for example in the electrical engines of wind turbines, and power trains of electric cars. The most effective electrical engines contain permanent magnets on their internal rotor, which require a high magnetisation, coercivity, and curie temperature in order to operate efficiently over the range of conditions the motor may be placed in. In high performance electrical engines Nd2Fe14B is the magnet of choice with some of the neodymium replaced with dysprosium to increase curie temperature giving (Nd, Dy)2Fe14B.1. Miyake et al. theoretically investigated a new magnetic structure, NdFe12N, showing it to have improved magnetic properties over Nd2Fe14B, confirmed later on by Hirayama et al. when grown epitaxially before having its properties investigated

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Conclusion