Structural, magnetic, dielectric and optical properties of double-perovskite Bi2FeCrO6 ceramics synthesized under high pressure

• Published in: Journal of alloys and compounds 2020-04, Vol.819, p.153007, Article 153007
• Main Authors: Wu, Heng, Pei, Zhipeng, Xia, Weiren, Lu, Yao, Leng, Kai, Zhu, Xinhua
• Format: Article
• Language: English
• Subjects: Absorption spectra; Antiferromagnetism; Bi2FeCrO6 ceramics; Ceramic powders; Ceramics; Chemical synthesis; Chromium; Crystal structure; Crystallization; Dielectric loss; Dielectric properties; Double perovskites; Energy gap; Ferromagnetism; High-pressured solid-state reaction; Lattice vacancies; Magnetic properties; Magnetization curves; Morphology; Optical properties; Oxidation; Oxygen; Photoelectrochemical devices; Photoelectrons; Photovoltaic cells; Room temperature; Structural characterization; Sunlight; Temperature dependence
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2019.153007

We report on double-perovskite Bi2FeCrO6 ceramics synthesized by solid-state reaction under high pressure of 6 GPa and temperature of 1000 °C. Its crystal structure was refined by X-ray powder diffraction data, and the Bi2FeCrO6 ceramics crystallized in rhombohedral structure with R3c space group. The ceramic grains exhibited polyhedron morphology with average size of 2.80 μm. The atomic ratio of Bi:Fe:Cr was determined to be 2.04:1.00:1.00, close to the nominal value. X-ray photoelectron spectra confirmed the dual oxidation states of ion (Fe2+ and Fe3+) and chromium (Cr3+ and Cr6+) in the Bi2FeCrO6 ceramics and oxygen in the forms of lattice oxygen and oxygen vacancies. Bi2FeCrO6 ceramics exhibits both antiferromagnetic and ferromagnetic orders, which are reflected in the unique temperature dependent magnetization curves. In addition, Bi2FeCrO6 ceramics also have large dielectric constant (∼508 at 1 kHz) and small dielectric loss (0.38 at 1 MHz) at room temperature. The direct band gap of the Bi2FeCrO6 ceramics deduced from their UV–Vis–NIR absorption spectra, was ∼1.50 eV, which was small enough to absorb the sunlight at wavelengths below 829 nm. A strong absorption peak was also observed at 600 nm in the absorption spectra of the Bi2FeCrO6 ceramics. These findings demonstrate that the Bi2FeCrO6 ceramics with a narrow direct band gap can effectively absorb the main portion of the sunlight spectrum (i.e., visible lights) and have promising applications in the fields of photoelectrochemical devices and photovoltaic devices. •Double perovskite Bi2FeCrO6 ceramics were synthesized under 6 GPa and 1000 °C.•The ceramics crystallized in rhombohedral structure with R3c space group.•The ceramics have large dielectric constant and small dielectric loss at RT.•The ceramics exhibits both antiferromagnetic and ferromagnetic orders.•The direct band gap is ∼1.50 eV and a strong absorption peak is observed at 600 nm.