Novel recording media: Fe14R2B particles

Conditions for hydrogen absorption and methods of preparing fine particles of Fe14R2B (R=Nd,Y,Ce) via hydriding are described. Hydrogen absorption and desorption are of the above-critical type (no phase segregation). Sub-micron sized particles can be prepared by repeated desorption cycles, making use of the decrepitation inherent in the hydriding process. The neodymium compound decomposes under hydrogen at 650°C and 10⁷Pa, forming NdH2, Fe, and Fe-B. Recombination is achieved by prolonged heating at 1100°C in a vacuum. Vibrating sample magnetometry and Mössbauer spectroscopy were used to measure the magnetic properties of the material before and after hydriding, together with scanning electron microscope observations of the particles formed.