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US researchers claim to have developed a significantly cheaper way to make samarium cobalt, the material behind high-temperature rare earth magnets.

Of the rare-earth materials, SmCo magnets are not quite as strong as the NdFeB types used in disk drives and toys, but far more temperature resistant - making them desirable in professional motors and generators.

"The direct chemical synthesis process is able to produce samarium cobalt rapidly and in large amounts, at a small fraction of the cost of the current industry method," said Massachusetts-based Northeastern University. "Until now, producing samarium cobalt has been a difficult and expensive multi-step process."

In essence, the Northeastern process involves dissolving nitrates of cobalt and samarium in tetraethylene glycol, then heating the mixture to temperatures between 100 and 200°C.

'Nanoblades' - thin flakes approximately 10x100nm - of SmCo form in the solution.

"Such unusually shaped particles should prove valuable in the processing of anisotropic magnets that are highly sought in many military and commercial applications, and are anticipated to lead to lighter and more energy-efficient end products," said lead researcher Dr CN Chinnasamy.

Rare earth magnets are made by sintering - compressing and heating powder - or by mixing magnetic powder with glue.

Chinnasamy claims the nanoblades, which achieve room temperature intrinsic coercivity of 6.1kOe and a magnetisation of 40emu/g, will be suitable for forming into such magnets.

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