Textured Sc-Doped Barium–Ferrite Compacts for Microwave Applications Below 20 GHz

Abstract

Sc is substituted for Fe in Ba M-type hexaferrite to reduce the anisotropy field and shift the ferromagnetic resonance (FMR) frequency to below 20 GHz. We have produced pure phase BaFe <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$_11$</tex> ScO <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$_19$</tex> powders having a platelet microstructure. These materials are pressed under an applied magnetic field of 95.5 <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$times$</tex> 10 <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$^5$</tex> A/m. Resulting compacts are sintered and are shown to have a clear uniaxial anisotropy with the <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$c$</tex> -axis perpendicular to the surface plane. Hysteresis loops display a squareness of 0.83 with a coercivity of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$sim $</tex> 186 kA/m. The <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$X$</tex> -band FMR power derivative linewidth is measured to be 79.6 kA/m.