Magnetic and dielectric properties of Ca-substituted BiFeO nanoferrites by the sol-gel method.

BACKGROUND

A multiferroic material can simultaneously show two or more basic magnetic properties, including ferromagnetism, antiferromagnetism, and ferroelectricity. BiFeO is a multiferroic material with a rhombohedral distorted perovskite structure. Doping can reduce the volatility of Bi and greatly improve the magnetoelectric properties of BiFeO.

METHODS

To investigate the influence of the doping content we used the following analytical methods: X-ray powder diffraction (XRD), scanning electron microscopy (SEM), microwave network analysis (PNA-N5244A), and the Superconducting Quantum Interference Device (Quantum Design MPMS) test.

RESULTS

With the increase of Ca concentration in the solution, the grain size of BiCa FeO becomes smaller, showing the role of Ca ions as the dopant for fine grains. The calcination temperatures are the major causes for the saturated magnetization. The residual magnetization ( M) and the coercive force ( H) decrease linearly with the increase of x value, and due to the effect of Ca substitution at Bi sites, which causes the valence change of Fe and/or the oxygen vacancies.

CONCLUSIONS

The XRD result indicates that the diffraction peak emerges with the increase of Ca and the main diffraction peak achieves a high angle. The best calcining temperature is 600 °C, and the morphology is very dependent on the calcining temperature.