研究目的
To investigate the La-induced structural phase transitions in multiferroic BiFeO3 ceramics and understand the structure-property correlations of RE-doped BiFeO3.
研究成果
The study reveals that La3+ dopants substitute the Bi site of a secondary nanosized particles with orthorhombic Pbam symmetry instead of the parental rhombohedral R3c phase in all La3+ doping concentrations (0.001 ≤ x ≤ 0.200). This finding challenges the prevailing assumption of La substitution on the Bi3+ site in R3c structure and suggests a new perspective on the structural phase transitions in BiFeO3-based materials.
研究不足
The study is limited to La-doped BiFeO3 ceramics with La concentrations up to x = 0.200. The detection of nanosized secondary phases by XRPD is challenging until La content approaches x = 0.100.
1：Experimental Design and Method Selection:
The study employs x-ray absorption fine structure spectroscopy (XAFS) to explore the structural phase transition in Bi1-xLaxFeO3 ceramics. Theoretical exploration and complementary studies of transmission electron microscopy and thermodynamic preference are also conducted.
2：Sample Selection and Data Sources:
Polycrystalline Bi1-xLaxFeO3 (0 ≤ x ≤ 0.200) powders were synthesized by sol-gel method. The crystalline phases were determined by XRPD, and XAFS spectra were acquired at the 1W1B beamline of Beijing Synchrotron Radiation Facility (BSRF).
3：200) powders were synthesized by sol-gel method. The crystalline phases were determined by XRPD, and XAFS spectra were acquired at the 1W1B beamline of Beijing Synchrotron Radiation Facility (BSRF).
List of Experimental Equipment and Materials:
3. List of Experimental Equipment and Materials: Bruker D8-Advanced x-ray diffractometer, JEOL JEM-ARM200F STEM, Si(111) double crystal monochromator, 32-element Ge detector, Lytle-type detector.
4：Experimental Procedures and Operational Workflow:
The samples were synthesized, characterized by XRPD, and analyzed by XAFS spectroscopy. HRTEM and thermodynamic calculations were performed to support the findings.
5：Data Analysis Methods:
The acquired XAFS raw data were processed by the standard procedures using the IFEFFIT package. Rietveld refinement method was used for XRPD data analysis.
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