Structural characterizations and dielectric, magnetic, and optical properties of Ba2FeVO6 double perovskite ceramics

摘要

Here, we present the structural characterization and physical properties of Ba 2 FeVO 6 (BFVO) ceramics prepared by the solid-state ceramic method, which is regarded as potential Mott multiferroics. Structural studies demonstrate that the BFVO ceramic samples crystallize in a hexagonal structure with R 3 c symmetry. SEM images show a spherical morphology of the ceramic grains with an average composition of Bi:Fe:V close to 2.0:1.0:1.0 determined by x-ray energy dispersive spectroscopy. Infrared spectra revealed the vibrational modes of [FeO 6 ] and [VO 6 ] octahedrons in the ceramics, and XPS spectra confirmed the dual chemical valence states of iron (Fe 2 and Fe 3 ) and vanadium (V 3 and V 4 ) and two states of oxygen species in the BFVO ceramics, while barium was present as Ba 2 . The BFVO ceramics exhibit relaxor-like dielectric behavior with an activation energy of 0.62 eV. The antiferromagnetic (AFM) nature was confirmed in the BFVO ceramics, whereas a weak magnetism was observed at 2 K. The temperature dependence of magnetizations measured with (and without) field cooling across 2 K–300 K under external magnetic fields indicates the spin glass characteristics in the present system. A strong variation of the dielectric behavior observed close to the AFM transition temperature was due to the induced dielectric polarization via the magnetostrictive effect driven by AFM transition. The bandgaps ( E g ) of the investigated ceramic samples were deduced from their UV–visible spectra. The E g values were about 1.15 eV and 1.50 eV, which were ascribed to the d–d electronic transitions of Fe 3 d t 2g → Fe 3 d e g and 6 A 1g → 4 T 1g , respectively.