研究目的
To enhance the dielectric constant of PVDF through introducing BaTiO3 in the PVDF matrix to make flexible dielectric materials for various applications including flexible capacitors, and to investigate dielectric properties over a wide range of frequency and temperature.
研究成果
The PVDF/BaTiO3 nanocomposite films successfully enhanced dielectric constant and exhibited significant dipolar relaxation. The dielectric constant increased with BaTiO3 content, attributed to interfacial polarization and phase transition to β-PVDF. Below 200 K, materials behaved as non-polar, with activation energies confirming dipolar processes. The increase in dipole density and decrease in relaxation time with filler content highlight the potential for flexible capacitor applications, suggesting further optimization for improved dispersion and performance.
研究不足
Deviations from theoretical predictions (e.g., Jaysundere-Smith model) at higher filler concentrations due to imperfect dispersion of BaTiO3 nanoparticles and agglomeration, as the model does not account for particle size effects. The study is limited to specific composite ratios and may not generalize to other filler types or concentrations.
1：Experimental Design and Method Selection:
The study involved preparing PVDF/BaTiO3 nanocomposite films using the solution casting method with dimethylformamide as solvent. Dielectric measurements were conducted to analyze dielectric constant and loss tangent as functions of frequency and temperature. Theoretical models like Jaysundere-Smith were used for comparison.
2：Sample Selection and Data Sources:
Samples included pristine PVDF and (1-x)PVDF/(x)BaTiO3 composites with x=0.1, 0.2, 0.3, 0.4, and 0.5. BaTiO3 nanoparticles were synthesized via co-precipitation, and composite films were fabricated via tape casting.
3：1, 2, 3, 4, and BaTiO3 nanoparticles were synthesized via co-precipitation, and composite films were fabricated via tape casting.
List of Experimental Equipment and Materials:
3. List of Experimental Equipment and Materials: Equipment included Agilent E4980A Precision LCR Meter for dielectric measurements, FESEM for microstructural analysis, XRD and FTIR for phase characterization. Materials included PVDF, BaTiO3 nanoparticles, dimethylformamide, barium acetate, titanium isopropoxide, ethylene glycol, silver paste.
4：Experimental Procedures and Operational Workflow:
BaTiO3 synthesis involved dissolving precursors, stirring, drying, and calcination. Composite preparation involved dissolving PVDF in DMF, adding BaTiO3, sonicating, casting films, and drying. Dielectric measurements were performed from 80 to 425 K and 20 Hz to 2 MHz, with electric contacts made using silver paste.
5：Data Analysis Methods:
Data analysis included frequency and temperature dependence plots, Cole-Cole analysis for dielectric strength and dipole density, Arrhenius plots for activation energy, and comparison with theoretical models.
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