Frequency-temperature dependent dynamics of dielectrics in ferric oxoborate Fe₃BO₆ of cocktail structure of nanorods

Abstract

Oxoborates have both dielectric and magnetic properties useful for magnetodielectric devices, sensors, or biological tools. Such compounds Fe₂BO₄, Fe₃BO₅, or Fe₃BO₆ are known to grow easily as single crystals in a liquid flux. A polycrystalline phase forms only on controlled conditions of a solid state reaction of the basic oxides. In this study, we report highly dielectric Fe₃BO₆ when grown in a specific shape of nanorods (∼200 nm diameter and 50–100 µm length) from an iron borate glass, which offers devisable shapes of sheets, discs, and fibers. Frequency (f)-temperature reliant dynamics of dielectric constant ε_r is studied over 25–300°C at 0.1–10³kHz frequencies. At low frequency such as 100 Hz, a large ε_r -value 40,000, better than most of high ε_r -value ferroelectrics, incurs at room temperature. At f ≥ 50 kHz, although only an order of diminished ε_r -value lasts, it increases steadily with temperature, possibly due to increasing electrical conductivity in a specific resistor–capacitor network. Suppressed dielectric relaxation and spin-flops share a merely weak spin-reorientation transition near 160°C. A stable power loss ≤0.5 lasts at f > 10 kHz useful for possible applications of magnetodielectric materials.

Keywords:

• magnetodielectric materials
• oxoborates
• microstructure
• nanoceramics
• dielectric materials

Acknowledgements

This study has been supported by a research grant from the Council of Scientific and Industrial research (CSIR), Government of India.