Analysis of the alternating current conductivity and magnetic behaviors for the polycrystalline Y-type Ba0.5Sr1.5Co2(Fe1-xAlx)12O22 hexaferrites

Co2Y hexaferrites have attracted intensive interests due to its potential high temperature magnetoelectricity as the single phase multiferroics. Numerous efforts have been paid to enhance their magnetoelectric properties at high temperatures through increasing the magnetic transition temperature and decreasing the conductivity. In this work, we investigated the conductivity and magnetic properties of the polycrystalline Ba0.5Sr1.5Co2(Fe1-xAlx)(12)O-22 (0 <= x <= 0.12) hexaferrites and found that Al-doping has important effects on both the conductivity and magnetic properties. The underlying physical mechanisms were also systematically analyzed. Most importantly, a very much enhanced resistivity (over 10M Omega cm), and a high magnetic transition temperature (similar to 346 K) have been obtained at a doping amount of x = 0.04. These improvements are very promising for achieving significant magnetoelectric effect at room temperature. The current research can provide the basic understanding of the Y-type ferrites for future applications in magnetoelectric and other fields. (C) 2014 AIP Publishing LLC.