Multiferroic ceramics in BaO–Y_2O_3–Fe_2O_3–Nb_2O_5 system

摘要

Multiferroic ceramics in BaO–Y_2O_3–Fe_2O_3–Nb_2O_5 system were synthesized and their dielectric, ferroelectric and magnetic properties were evaluated. XRD results showed that the ceramic composite consists of a major phase of tetragonal tungsten bronze structured Ba_2YFeNb_4O_(15), and minor phases of monoclinic YNbO_4 and hexagonal Ba_3Fe_2Nb_6O_(21). Three dielectric relaxations were observed in the temperature range from 125 to 575 K. The relaxor dielectric behavior in the temperature range from 125 to 350 K was attributed to the random occupation of Fe~(3+) and Nb~(5+) ions at B site of the tungsten bronze structure. The electrode polarization and the inhomogeneous structure contributed to the high-temperature and middle-temperature dielectric relaxations, respectively. Both the ferroelectric hysteresis loop and the magnetic hysteresis loop were measured, which suggested that the synthesized ceramic composite was a promising candidate of multiferroics.