Abstract: A method for sintering Mn--Zn ferrite green compacts is provided which includes a first heating step of raising the temperature from room temperature to 600.degree. C. within a period from 30 minutes to 5 hours, a second heating step of raising the temperature from 600.degree. C. to the sintering temperature and holding the sintering temperature until the start of cooling within a period shorter than 10 hours, and a cooling step of lowering the temperature to 150.degree. C. within a period longer than 3 hours, with the total period of the three steps being shorter than 20 hours. This method permits the efficient production in a short time of Mn--Zn ferrites having good magnetic properties.

Abstract: Ti or a high-Ti alloy is melted in a container composed of high-purity CaO materials on its inner sides. The materials are composed of not less than 99% by weight of CaO, not more than 0.1% by weight of SiO.sub.2, not more than 0.02% by weight of Fe.sub.2 O.sub.3, and not more than 0.5% by weight in total of other metal oxides under a non-oxidizing atmosphere.CaO refractories for use in the melting of Ti or a high-Ti alloy contains not less than 99% by weight of CaO, not more than 0.1% by weight of SiO.sub.2, 0.02% by weight of Fe.sub.2 O.sub.3, and not more than 0.5% by weight of other metal oxides.