LAUSR

Abstract We have fabricated flaky carbonyl iron particles (CIPs) with (200) crystal planes and easy axes preferred to parallel to the flake surfaces by developing a slip-induced grain orientation method. The method involves heat-treatment and subsequent wet milling of spherical CIPs. The heat-treatment in inert atmosphere is used to grow the grain sizes of raw spherical CIPs. During the wet milling process, the large grains in the heat-treated spherical CIPs are preferred to slip along directions {110} and rotate to produce (200) preferred orientation while they are being compressed into flaky shape. The grain orientation factor (a) increases from 0 to 0.42 with grain sizes grown up by controlled heat-treatment temperature. The texture decreases the in-plane magnetic anisotropy field of the flaky CIPs. The aligned flaky textured CIPs brings about an additional magnetic resonance at low frequency with respect to the non-textured counterpart, and exhibit enhanced double magnetic resonances. When a = 0.42, the imaginary permeability peak reaches 3.52 at 0.7 GHz, which is 2 times larger than previously reported values. The reflection loss less than −10 dB for their-based absorbing composite slab at thickness of 1 mm can cover a wide low frequency range between 0.4 and 2 GHz when the volume fraction of aligned textured flaky CIPs changes from 40 to 50%. This work provides an effective route to enhance magnetic permeability and loss at low frequencies, which has been a great challenge in recent years.