Freeze-Cast Porous Textured BaTiO₃-Polymer Composites for Energy Harvesting Applications.

Area of Science:

• Materials Science
• Ceramics Engineering
• Nanotechnology

Background:

• Porous piezoelectric ceramics offer high piezoelectric coefficients and low permittivity, ideal for sensing and energy harvesting.
• Crystallographic texturing in porous lead-free piezoceramics can further enhance performance.
• Aligned porous structures are crucial for optimizing piezoelectric properties.

Purpose of the Study:

• To develop a method for fabricating lead-free porous textured BaTiO3 ceramics with aligned porosity.
• To investigate the effect of polymer infiltration on the mechanical and piezoelectric properties of the fabricated ceramics.
• To demonstrate the energy harvesting and sensing capabilities of the developed materials.

Main Methods:

• Directional freeze-casting of BaTiO3 platelets to create aligned porosity.
• Scanning electron microscopy (SEM) for microstructure analysis and alignment confirmation.
• X-ray diffraction (XRD) to quantify crystallographic texturing using the Lotgering factor (LF).
• Polymer infiltration with epoxy and polydimethylsiloxane (PDMS) to enhance mechanical properties.
• Characterization of dielectric, ferroelectric, and piezoelectric properties.
• Fabrication of a cantilever structure for energy harvesting and sensing demonstration.

Main Results:

• Achieved highly aligned porosity and crystallographic texturing (LF ≈ 0.37) in porous BaTiO3 ceramics.
• Polymer infiltration significantly improved mechanical strength and strain to failure.
• The BaTiO3-epoxy composite showed high failure stress (71.6 MPa) and moderate strain (0.93%).
• The BaTiO3-PDMS composite exhibited flexibility with a low Young's modulus (0.015 GPa) and high strain (>22%).
• Demonstrated energy harvesting and sensing performance using a BaTiO3-epoxy composite cantilever.

Conclusions:

• Directional freeze-casting is an effective technique for producing aligned porous and textured ferroelectric microstructures.
• Polymer infiltration enhances the mechanical robustness and flexibility of porous piezoceramics.
• The developed materials show significant potential for advanced sensing and energy harvesting applications.