Enhanced electromagnetic wave absorption of Y2Fe16Si by atomic layer deposition coating

Surface modification of metallic magnetic powders is important to regulate high-frequency electromagnetic properties for microwave absorbing composite materials composed of these powders and insulating media. In this study, atomic layer deposition (ALD) was applied to coat metallic magnetic Y2Fe16Si powder with uniform Al2O3 layer to improve its high-frequency electromagnetic properties. The thickness of the coating layer was characterized by transmission electron microscopy and x-ray photoelectron spectroscopy methods, with an average value of approximately 50 nm. It was found that the coating layer can significantly decrease the permittivity, and hence improve the impedance matching and the microwave absorption capability of the Y2Fe16Si@Al2O3–paraffin composite. A high reflection loss of −63 dB was achieved at 9.9 GHz with a thickness of 2.2 mm, and an effective absorption bandwidth of 6.4 GHz was obtained at 1.6 mm. This study demonstrates the potential of ALD technology for optimizing the electromagnetic properties of metallic magnetic powder materials for better microwave absorption.