Sintering of ferrite-BaTiO3 bulk particulate composites

Particulate magnetoelectric ceramic composites (PMCC) have received much attention since the last decade. These composites have many technological applications and are usually composed by magnetostrictive and piezoelectric phases. Cobalt-based spinel ferrites are among the most studied magnetostrictive phases for ferritebased PMCCs and BaTiO3 is an interesting choice for the piezoelectric phase because it is a lead-free ceramic, unlike the traditional PZT. In this work, cobalt ferrite (FCO) and Ni?Co ferrite (FNICO) were produced by the ceramic method and mixed to BaTiO3 (TB) in order to further obtain sintered ferrite-BaTiO3 particulate ceramic composites with a composition of 15 mol% ferrite ? 85 mol% BaTiO3. The ferrites, the BaTiO3, and the ferriteBaTiO3 mixtures were analyzed by dilatometry, thermogravimetry (TG), and calorimetry (DSC) in temperatures up to 1300?1400 ?C, with the aim to analyze the sintering behavior and the interactions between both ferrites and the BaTiO3 during sintering. Sintered TB-FNICO and TB-FCO composite samples were also produced and they were analyzed by scanning electron microscopy (SEM) and X-ray diffractometry (XRD). The dilatometry results evidenced that the densification of the ferrite-BaTiO3 samples is impaired, when compared to the pure ferrite and BaTiO3 samples. The DSC/TG results evidenced the occurrence of reactions between the ferrites and the BaTiO3 when they are co-sintered in air or argon atmospheres. The XRD patterns of the sintered composite samples did not exhibit diffraction peaks attributed to a third phase, whilst the punctual EDS analysis showed evidence of diffusion between the ferrite and BaTiO3 particles.

Automated summary

This study prepared sintered ferrite-BaTiO3 composite samples by mixing cobalt ferrite and nickel-cobalt ferrite with BaTiO3, and analyzed their sintering behavior and interactions through dilatometry, thermogravimetry, and calorimetry. The results showed that the densification of the composite samples was affected, and reactions between the ferrites and BaTiO3 occurred during sintering.