Study on electrical and magnetic properties of Nd-Co co-substituted M-type strontium ferrite suitable for microwave devices

Solid-state method was used to make Nd-Co co-substituted strontium ferrite (NdxSr1 - xCoxFe12 - xO19, x=0.00-1.00) samples. When x <= 0.20, the coercivity rose from 3353.00 to 4045.20 Oe. The saturation magnetization declined by 2.58 percent, from 64.39 to 62.73 emu/g. At the same time, when x<0.20, the sample's resistivity exhibits a unique bimetal-semiconductor transition behavior and the image of resistivity shifts to the low-temperature direction. When x=0.30, a clear alpha-Fe2O3 phase appears on XRD pictures. Furthermore, when x >= 0.30, the amount of alpha-Fe2O3 grows as the replacement amount increases. Finally, when x=1, the sample's coercivity drops to 600.44 Oe and the saturation magnetization drops to 15.56 emu/g. The magnetic properties of the samples show high coercivity, high saturation magnetization, and their electrical properties show special metal-semiconductor transition behavior.