研究目的
Investigating the structure and magnetic properties of polycrystalline BiFeO3 films grown on glass substrate using Sol-Gel technique.
研究成果
The polycrystalline BiFeO3 films exhibit an average crystallite size of 21 nm and RMS roughness of 50 nm. FMR studies confirm ferromagnetic behavior with uniaxial out-of-plane anisotropy. ZFC and FC measurements indicate a spin glass state due to negative exchange coupling and interfacial effects. Magnetic crystallite sizes from magnetization studies align with structural data, supporting the findings on multiferroic properties.
研究不足
The paper mentions impurity peaks of Bi2O3 and Bi-rich secondary phases in XRD, indicating challenges in achieving single-phase BiFeO3. The sol-gel method may lead to variations in grain size distribution, affecting magnetic properties. No specific optimization areas are detailed, but the presence of impurities suggests potential for improved synthesis conditions.
1：Experimental Design and Method Selection:
The study used sol-gel method for film preparation, with dip coating technique on glass substrates. Structural analysis via XRD and SEM, magnetic characterization via FMR and VSM magnetometry.
2：Sample Selection and Data Sources:
BiFeO3 thin films were synthesized using bismuth(III) nitrate and ferrum nitrate nonahydrate as starting materials, dissolved in solvents and mixed. Films deposited on glass substrates.
3：List of Experimental Equipment and Materials:
X-ray diffractometer with Cu Kα radiation, scanning electron microscope (SEM), Bruker EMX model X-band spectrometer for FMR, VSM Magnetometer (PPMS, Quantum Design Corp.), glass substrates, chemicals like Bi5O(OH)3?(NO3)4, Fe(NO3)3?9H2O, 2-Methoxyethanol, glacial acetic acid, triethanolamine, ethanol, acetic anhydride, ethanolamine.
4：Experimental Procedures and Operational Workflow:
Solution preparation by mixing and stirring, dip coating at 15-20 cm/min, drying at 350°C, annealing at 450-600°C for 3 minutes. XRD for structure, SEM for morphology, FMR at room temperature with out-of-plane geometry, magnetization measurements with ZFC and FC protocols from 10 K to 400 K at 100 Oe.
5：Data Analysis Methods:
Debye-Scherer method for grain size from XRD, RMS roughness from SEM, fitting of FMR data using Smit and Beljers formula, Langevin function fitting for superparamagnetic behavior.
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