A comparative study of the dielectric, ferroelectric and anomalous magnetic properties of Mn0.5Mg0.5Fe2O4/Ba0.8Sr0.2Ti0.9Zr0.1O3 composite ceramics.

Mn 0.5 Mg 0.5 Fe 2 O 4 /Ba 0.8 Sr 0.2 Ti 0.9 Zr 0.1 O 3 composite ceramics were prepared by sol-gel method and the effects of molar ratio (3:1, 2:1, 1:1, 1:2, 1:3) between the magnetic and ferroelectric phases on the microstructure, dielectric, ferroelectric and magnetic properties have been comparatively investigated. The results indicate that the obtained composite ceramics show bi-phase structure, without other apparent impurities. The surface is relatively uniform except for some pores, and the grain size of all the samples is near 1 μm. The dielectric constant shows decreasing trend with the molar ratio while the loss presents the opposite behavior. Only one relaxation peak can be observed when the molar ratio is less than 1:1, but two peaks are found when the molar ratio exceeds 1:1. The height of the peak decreases with the frequency and molar ratio while the position shifts to higher temperature range with the molar ratio. The dielectric loss increases sharply with the temperature and it is amounts to several thousand when the temperature is lager than 300 °C in the lower molar ratios. Both the resident polarization and coercive electric field increase with the measured voltage while they decrease with the frequency. The leakage current decreases with the molar ratio due to the lower conductivity of Mn 0.5 Mg 0.5 Fe 2 O 4. The magnetization shows a monotonic variation behavior with the molar ratio, indicating the strong interface interaction between the two phases. The maximal ME coupling coefficient is about 800 mV/(cm.Oe) for the sample 3:1 due to the stronger magnetic properties. • Mn 0.5 Mg 0.5 Fe 2 O 4 /Ba 0.8 Sr 0.2 Ti 0.9 Zr 0.1 O 3 composites were prepared by sol-gel method. • The obtained composite ceramics show bi-phase structure, with the grain size of all the samples is near 1 mm. • Relaxation peaks can be observed in the temperature dependence of dielectric constant. • The magnetization shows abnormal behavior due to the strong interface interaction between the two phases. [ABSTRACT FROM AUTHOR]