Preparation and characterization of the spinel series Co6+xNi4-xMn8O24 (0 <= x <= 4)

Samples of the spinel series, Co6+xNi4-xMn8O24 (0 less than or equal to x l ess than or equal to 4), prepared by traditional ceramic procedures, are ch aracterized by X-ray diffraction, SEM techniques and magnetization measurem ents. In the whole concentration range, a single-phase cubic spinels are ob tained at a sintering temperature of 1050 degrees C for a period of time of 72 h. SEM analysis showed that the ceramics are well densified and consist ed of well individualized grains of a narrow size distribution. Magnetizati on measurements revealed the existence of a Yafet-Kittel configuration at l ow temperature and a ferrimagnetic-paramagnetic transition with increasing temperature. The Curie temperature decreased from 250 K for x = 2.5 to 200 K for x = 4.