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 less than or equal to 4), prepared by traditional ceramic procedures, are characterized by X-ray diffraction, SEM techniques and magnetization measurements. In the whole concentration range, a single-phase cubic spinels are obtained 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 consisted of well individualized grains of a narrow size distribution. Magnetization measurements revealed the existence of a Yafet-Kittel configuration at low 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.