Development of NanoCAP (nano composite advanced particles) technology for high density recording
In this paper, nanosized spherical magnetite particles, with the coercivity force of about 3000 Oe was developed. This material was named NanoCAP (nano composite advanced particles). This study described both magnetic and structural properties of NanoCAP. The crystal structure and the microstructure of the particles were examined using an X-ray diffractometer and high resolution transmission electron microscope, respectively. The obtained magnetization and coercivity of the particles were 89 emu/g and 2900 Oe, respectively. NanoCAP is expected to be the most promising candidate for ultrahigh capacity recording tapes.
Magnetic Properties of Fe16N2 Fine Particles.
Heat conditions for synthesis of Fe16N2 tine particles and the resulting magnetic properties were investigated. Commercial ultra fine γ - Fe2O3 particles were first reduced under hydrogen gas at temperatures between 200°C and 700°C for 8 hours and nitrided under an ammonia-argon mixed gas at 140°C for 24 hours. The powder reduced at 500°C and nitrided at 140°C was identified as nearly Fe16N2 single phase by X-ray diffraction and Mossbauer analysis. Saturation magnetization at room temperature was about 200 emu/g. Maximum coercive force (2250 Oe) was achieved in the Fe16N2 powder with the largest specific surface area.
The magnetization of bulk α‘Fe16N2 (invited)
Evidence for giant magnetic moments in the metastable nitride α‘Fe16N2 is reviewed, with reference to the related stable nitride γ’Fe4N and αFe. It is concluded from a survey of electronic structure calculations, Mossbauer spectra, and magnetization measurements on bulk multiphase samples that the average iron moment in α‘Fe16N2 at T∼0 lies in the range 2.3–2.6 μB. A significantly larger moment of about 2.9 μB appears on the 4d sites which have no nitrogen neighbors.