High heat generation ability in AC magnetic field of Y3Fe 5O12 powder prepared using bead milling

Abstract

We found that the nano-sized Y3Fe5O12 powder prepared by bead milling has the highest heat generation ability in an AC magnetic field of reported superparamagnetic materials. The heat generation ability in an AC magnetic field was strongly improved by a decrease in the average crystallite size of the bead milled samples. The highest heat ability in the AC magnetic field was for the fine Y3Fe5O 12 powder with ca. 15 nm crystallite size (the samples milled for 4 h using 0.1 mmohm beads). The reasons for the high heat generation properties of the milled samples are ascribed to an increase in the Néel relaxation of the superparamagnetic material. The heat generation ability (W·g -1) can be estimated using a 3.58 × 10-4 f·H2 frequency (f/kHz) and the magnetic field (H/kA·m-1) for the sample milled for 4 h using 0.1 mmohm beads. © 2011 The American Ceramic Society.