Microwave-Assisted Solvothermal Route for One-Step Synthesis of Pure Phase Bismuth Ferrite Microflowers with Improved Magnetic and Dielectric Properties

Abstract

The prototypical plum-free, one-phase multiferric ferrite BiFeO 3 (BFO) is solid, parallel, with a high ferroelectric Curie temperature and Neel temperature and antiferromagnetic and ferroelectric propagation. This work aims to synthesize pure-phase BFO in the quickest possible way. We followed the microwave-assisted solvothermal (MWAST) method to achieve pure-phase BFO in the shortest duration of 3 min. The experiment involves simple optimizations with KOH concentration and microwave power levels. The surface morphology along with magnetic properties of BFO synthesized via the MWAST method are altered with varying KOH concentrations and microwave (MW) power levels. Our X-ray diffraction findings reveal that the pure-phase BFO is formed at 800 W MW power, and the structural characterizations like transmission electron microscopy, field emission scanning electron microscopy with energy-dispersive X-ray analysis have displayed the formation of uniformly distributed spherical microflowers of pure-phase BFO exhibiting a single-crystalline nature. Besides, the magnetic measurements affirmed a reliable weak ferromagnetic behavior (magnetization ∼1.25 emu/g) in BFO synthesized at 800 W MW power. In addition, good dielectric behavior with low dielectric loss was accompanied by frequency-dependent dielectric studies indicating an excellent frequency response of the material, and also the room-temperature ferroelectric properties were studied using a ferroelectric analyzer. The polarization of pure-phase BFO increases with the applied electric field and exhibits unsaturated polarization–electric field loops due to leakage current. Moreover, the Fourier transform infrared spectrum of the synthesized material has indicated the pure-phase BFO, and the Raman data have elucidated the vibrational modes of BFO. Further, the analysis of X-ray photoelectron spectroscopy data has confirmed the presence of fewer Fe 2+ ions and oxygen vacancies in the pure-phase BFO. Therefore, the collective characterizations and detailed analysis of BFO material have revealed the uniqueness of the MWAST method in producing the pure-phase BFO in 3 min with improved magnetic and dielectric properties, and hence the BFO synthesized via the MWAST method can be a potential candidate for multiferroic applications.

Simple Low Temperature Technique to Synthesize Sillenite Bismuth Ferrite with Promising Photocatalytic Performance

“…The maximum magnetization at 50 kOe is 6.97 and 3.63 emu/g for S-BFO(140) and S-BFO(160) samples, respectively. Such a high magnetization value of S-BFO(140) is probably associated with the higher secondary phases present in the sample, which were not detected by the XRD technique due to its limit of detection. ,, This observation also suggests that our desired photocatalyst with a better sillenite structure is S-BFO(160) compared to that of S-BFO(120) and S-BFO(140).…”

“…A careful observation of the shape of the room temperature M-H loops of the as-synthesized S-BFO(140) and S-BFO(160) samples indicates a superposition of their paramagnetic and superparamagnetic nature, arising mainly from sillenite and some other phases. 56 To identify these phases and investigate their comprehensive role on magnetic behavior, further investigation is required. Nevertheless, we have observed the difference in room temperature magnetic behavior of our sillenite-type bismuth ferrite samples synthesized by co-doping of Gd and Cr to that of a perovskite phase Dy and Cr co-doped bismuth ferrite sample.…”

“…A careful observation of the shape of the room temperature M-H loops of the as-synthesized S-BFO(140) and S-BFO(160) samples indicates a superposition of their paramagnetic and superparamagnetic nature, arising mainly from sillenite and some other phases . To identify these phases and investigate their comprehensive role on magnetic behavior, further investigation is required.…”

The Relationship between Photoluminescence Emissions and Photocatalytic Activity of CeO2 Nanocrystals

“…67 Nucleation and crystal growth of nanostructures under hydrothermal/solvothermal conditions are governed by multiple parameters, such as temperature, time, environment, solvent type, precursor type, precursor concentration, pH, vessel size, solution volume, pressure, etc. 79 Regarding the solvothermal synthesis, three parameters associated with the solvent are known to influence the crystal growth, which are precursor solubility in a chosen solvent, solvent polarity, and their characteristic vapor pressure. 80 For instance, Mishra et al 31 synthesized CuO nanostructures via MAS using a water−ethylene glycol mixture as solvent.…”

“…Anisotropic growth of the CeO 2 NCs may be a result of the formation of complexes between cerium hydroxide and ethanol molecules, resulting in octahedral-like shaped nanoparticles (Figure e,f) . Nucleation and crystal growth of nanostructures under hydrothermal/solvothermal conditions are governed by multiple parameters, such as temperature, time, environment, solvent type, precursor type, precursor concentration, pH, vessel size, solution volume, pressure, etc . Regarding the solvothermal synthesis, three parameters associated with the solvent are known to influence the crystal growth, which are precursor solubility in a chosen solvent, solvent polarity, and their characteristic vapor pressure .…”