研究目的
Investigating the synthesis, structural properties, and piezoelectric potential of Ba1-xCaxTiO3 solid solutions using a topochemical conversion method from molten salt solutions with Bi4Ti3O12 templates.
研究成果
The synthesis of Ba1-xCaxTiO3 via topochemical conversion from molten salt solutions using Bi4Ti3O12 templates is feasible, but has limitations such as calcium solubility up to x=0.3 and residual bismuth contamination. The particles retain template shape at low calcium contents but undergo structural and morphological changes above x=0.3. Future work should include piezoelectric force microscopy (PFM) measurements to assess application potential.
研究不足
The synthesis is time-consuming, taking about three days per sample. There is a solubility limit for calcium in the BaTiO3 lattice, with secondary phases (e.g., CaTiO3) forming above x=0.3. Residual bismuth from the template is present in the final compositions, which may affect piezoelectric properties and requires further investigation.
1：Experimental Design and Method Selection:
The synthesis followed a topochemical conversion method from molten salt solutions, based on previous work by Kr?manc et al., to produce Ba1-xCaxTiO3 solid solutions with varying calcium content (x from 0 to 1) using Bi4Ti3O12 template seeds. The method aimed to control shape, size, crystal structure, and growth orientation.
2：Sample Selection and Data Sources:
Samples were prepared with different nominal calcium contents (x values). The Bi4Ti3O12 template was synthesized from bismuth oxide and titanium oxide mixed in NaCl/KCl salts, heated, and washed. For solid solutions, Ba2+ and Ca2+ precursors were mixed with NaCl/KCl salts and Bi4Ti3O12 templates, then heated in an alumina crucible at 900°C. The resulting particles were isolated via washing and centrifugation.
3：List of Experimental Equipment and Materials:
Equipment included an oven for heating, alumina crucibles, and centrifugation equipment. Materials included bismuth oxide, titanium oxide, NaCl/KCl salts, Ba2+ and Ca2+ precursors, and Bi4Ti3O12 templates.
4：Experimental Procedures and Operational Workflow:
The template was prepared by mixing oxides with salts, heating for several hours, and washing. For solid solutions, precursors and salts were mixed with templates, placed in crucibles, heated at 900°C, and then washed and centrifuged repeatedly to isolate Ba1-xCaxTiO3 particles. Each sample took about three days to prepare.
5：Data Analysis Methods:
Characterization techniques included X-ray diffraction (XRD) with Rietveld refinements to analyze structural parameters and tetragonality, electron microscopy (TEM and SEM) for microstructural analysis, and energy-dispersive X-ray spectroscopy (EDX) for composition analysis.
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