Magnetic properties of phase separated glasses and glass ceramics in Co3O4-TiO2-SiO2 system

The phase separated glass ceramics in Co3O4-TiO2-SiO2 ternary system were prepared by a melt-quenching method and their magnetic properties were investigated. The samples in the xCoO-(48.5 - 0.5x)TiO2-(48.5 - 0.5x)SiO2-3.0Al2O3 (x = 3, 5, 10) consisted of TiO2-rich particles and a SiO2-rich matrix and this phase-separated structure was formed by a nucleation-growth process. This phase-separated glass ceramics showed the magnetic hysteresis loop due to a mixture of ferromagnetic and paramagnetic phases. From the X-ray diffraction measurements, it was confirmed that the samples had the TiO2 rutile phase and amorphous phase without the other crystalline phases. The magnetic susceptibility increased and the coercive force decreased with increasing the amount of Co addition. These results indicated that the prepared samples had the ferromagnetic Co-doped TiO2 rutile phase and the paramagnetic amorphous phase which contains Co divalent ions