In-situ coated nanomagnets

Nanomagnets with controlled size distribution are produced by continuous hydrogen reduction technique and coated in situ by carbon or copper. The copper layer can be oxidised ex situ. The coated nanomagnets are well-protected against oxidation occurring over time or in elevated temperatures. The optical and electrical properties of the magnets are controlled by coating. The coating can also be functionalised. The saturation magnetization of all nanomagnets is close to that of bulk, Co, indicating a highly crystallised structure and the avoidance of oxidation. Copper coating increased the measured magnetic hysteresis.

Nanomagnets with carbon or copper coating have been produced with a continuous gas-phase technique. The figure shows carbon coated cobalt particles with a narrow size distribution. The size of the particles can be tailored between 17 and 80 nm.Figure optionsDownload as PowerPoint slideHighlights
► We have synthesized Co nanoparticles with C and Cu shells.
► The Cu shell was oxidised without oxidising the Co core.
► The magnetic properties resemble bulk Co except for smallest particles.
► The method is economic and can be scaled up.