Evolution of structural and functional properties of the Fe/BaTiO3 system guided by mechanochemical and thermal treatment

Abstract

Multiferroic systems are attractive to the researches worldwide due to diversity of existing applications, as well as possible novel ones. In order to contribute to understanding of the processes that take place within the structure of such a system, we subjected it to mechanochemical activation and thermal treatment. Powdery mixtures of iron and barium titanate in a mass ratio of 30% Fe and 70% BaTiO3 were activated in a planetary ball mill for time duration of 30 to 300 min and subsequently sintered at 1200?C in the atmosphere of air. During the activation the system undergoes structural phase transitions, whereby the content of iron and its oxides changes. The highest Fe content was observed in the sample activated for 270 min, with local maxima in crystallite size and microstrain values and a minimum in dislocation density. The complex dielectric permittivity changes in the applied radio frequency field, rangingfrom 176.9 pF/m in thesample activated for 90 min to 918.1 pF/m in the sample activated for 180 min. As the frequency of the field increases, an exponential decrease in the magnetic with a simultaneous increase in the electrical energy losses is noticeable. The system exhibits ferromagnetic resonance, whereby longer activation in the mill shifts the resonant frequency to higher values. Negative electrical resistance was observed in all analyzed samples. The activation time changes both the demagnetization temperature and the Curie temperature of the samples undergoing heating and cooling cycles in the external permanent magnetic field. Curie temperature is the highest in the sample activated for 240 min. Thermal treatment increases the initial magnetization of all samples, with the most pronounced increase of ~95% in the sample activated for 300 min. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. OI 172057]

Fourier-transform infrared spectroscopy analysis of mechanochemical transformation kinetics of sodium carbonate to bicarbonate

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Processing and properties of ceramic yttrium manganite sintered by different methods

“…The coexistence of ferroelectric and magnetic properties in one phase and possible control over magnetic properties with an electric field, and vice versa -electric properties with a magnetic field, also makes those materials interesting for various applications. Due to their unique properties, multiferroics, whether single phase or heterostructures, stand out as candidate materials for many devices with different functions, including information-storage devices, ferroelectric random access memories, spintronics and sensors, among others [1][2][3][4][5][6].…”