Powerful magnets are required for electric motors or wind turbines. However, for their production you need rare earths, the mining of which pollutes the environment and which is found only in a few countries – the hot spot is China. Austrian and British researchers have now succeeded in producing the mineral tetrataenite, known only from meteorites, in the laboratory. This would make it possible to produce such magnets without rare earth elements – and reduce dependence on individual exporters.
The group of rare earth elements includes 17 chemical elements that are indispensable for many high-tech products such as mobile phones. In addition, substances such as neodymium play an important role in electric motors or wind turbines, where very strong small permanent magnets are required. Neodymium and other rare earth metals are currently unrivaled for their production.
Market firmly in Chinese hands
This is viewed critically for two reasons: on the one hand, the extraction of the corresponding ores requires enormous effort and a great environmental burden: an enormous amount of material has to be extracted to obtain small quantities of rare earth elements. On the other hand, their precious promotion is firmly in Chinese hands – nine out of ten permanent magnets currently come from China.
Alternatives are therefore being intensively sought: this could be a natural alloy of iron and nickel called “tetrataenite”, the researchers report in the journal “Advanced Science”. The problem: The mineral has so far only been discovered in meteorites, and it usually takes millions of years to form.
“The structure of tetrataenite normally only arises when an iron-nickel mixture cools extremely slowly after its formation, at a rate of less than 0.01 degrees Celsius per year,” explains Baran Sarac from the Erich Schmid Institute for Materials Science Austrian Academy of Sciences from (ÖAW) in Leoben. The iron and nickel atoms thus form a specific crystal structure, resulting in a material with magnetic properties comparable to those of rare earth metals.
Phosphorus and carbon as a turbo
Sarac and his colleague Jürgen Eckert, together with colleagues from Cambridge University (UK), have now succeeded in accelerating this process enormously in the laboratory by adding small amounts of phosphorus and carbon to a melt of iron and nickel. “In a vacuum, we cast cylinders from one to three millimeters long and cool them down in a few milliseconds,” explains Sarac. The phosphorus allows the iron and nickel atoms to move faster, so that the necessary crystal structure is formed in that short time.
The scientists hope that the simple production process will make it possible to produce on an industrial scale in a relatively short time. They have applied for a patent on the new method and have contacted start-ups and large companies interested in the method.
Source: Krone
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