Development of high-quality ceramic powders for Sr/sub 0.9/Ca/sub 0.1/Zn/sub 2/-W type hexagonal ferrite for permanent magnet devices

Fine ceramic powders of Sr/sub 0.9/Ca/sub 0.1/Zn/sub 2/Fe/sub 16/O/sub 27/ (Sr/sub 0.9/Ca/sub 0.1/Zn/sub 2/-W) ferrite, of almost single domain grain size approximately 1 mu m, have been synthesized successfully by sintering for a few hours a mixture of SrCO/sub 3/, CaCO/sub 3/, ZnO, and alpha -Fe/sub 2/O/sub 3/ in stoichiometric amounts at an effectively low temperature (T/sub s/) of approximately 1100 degrees C. Carbon dioxide evolves in the reaction Sr(Ca)CO/sub 3/+2ZnO+8 alpha -Fe/sub 2/D/sub 3/ from or to Sr(Ca)Zn/sub 2/Fe/sub 16/O/sub 2/+C/sub 2/, making fine pores in the sample, which prevent large grain growth of the material and result in a very loose powder. The small