研究目的
To provide a comparative study of the dielectric and piezoelectric properties of randomly oriented and textured 0.88Na0.5Bi0.5TiO3-0.08K0.5Bi0.5TiO3-0.04BaTiO3 (88NBT) ceramics, and to investigate the enhancement in piezoelectric properties through texturing.
研究成果
Highly textured 88NBT ceramics with a Lotgering factor of 96% were successfully fabricated using the TGG method with NN templates. The textured ceramics exhibited enhanced piezoelectric properties, including a 25% increase in large signal piezoelectric coefficient d33* (200 pm/V) and reduced strain hysteresis (7.6%) compared to randomly oriented ceramics. This improvement is attributed to grain orientation along the <001> direction, leading to an engineered domain configuration. The findings demonstrate that texturing is an effective method to enhance piezoelectric performance in lead-free ceramics, with potential applications in energy-efficient devices. Future studies could focus on optimizing texturing parameters and exploring other lead-free systems.
研究不足
The textured ceramics showed slightly lower relative density (95%) compared to randomly oriented ceramics (96%), which may affect properties. The study focused on a specific composition (88NBT) and template concentration (4 wt% NN), and the impact of other compositions or template amounts was not explored. The electrical conductivity analysis was limited to high temperatures (340–500°C), and room temperature conductivity was not extensively discussed. Potential optimization areas include improving density and exploring other texturing parameters.
1：Experimental Design and Method Selection:
The study employed the template grain growth (TGG) method to fabricate textured 88NBT ceramics using NaNbO3 (NN) templates. The rationale was to control grain orientation along the <001> direction to enhance piezoelectric properties. The methods included double molten salts synthesis (DMSS) for NN templates, conventional solid-state reaction for matrix powders, tape-casting for slurry preparation, and sintering.
2：Sample Selection and Data Sources:
Samples included randomly oriented and textured 88NBT ceramics with MPB composition. Raw materials were Bi2O3, Na2CO3, TiO2, K2CO3, BaCO3, and NN templates. Data were acquired from synthesized ceramics.
3：List of Experimental Equipment and Materials:
Equipment: X-ray diffractometer (XRD, PANalytical X′ Pert PRO), quasi-static piezoelectric d33-meter (ZJ-3A), scanning electron microscope (SEM, JSM-7001F, JEOL), LCR meter (E4980A, Agilent), piezo-measurement system (aixACCT TF Analyzer 2000), high voltage amplifier (TREK 610E). Materials: Na2CO3, Nb2O5, Bi2O3, NaCl, KCl, TiO2, K2CO3, BaCO3, ethanol, deionized water, binder, solvents, plasticizers, dispersant, silicone oil.
4：Experimental Procedures and Operational Workflow:
NN templates were synthesized via DMSS from BNN5 precursors, washed, and reacted. 88NBT matrix powders were prepared by ball milling, drying, and calcination. Slurry was made by mixing matrix powders with NN templates, tape-cast, dried, laminated, and sintered. Samples were characterized for phase structure (XRD), microstructure (SEM), piezoelectric coefficient (d33-meter), dielectric properties (LCR meter), and ferroelectric properties (piezo-measurement system). Poling was done at 5 kV/mm.
5：Data Analysis Methods:
XRD data used for Lotgering factor calculation. Dielectric data analyzed for Td and Tm using temperature dependence. Complex impedance spectra fitted with equivalent circuit (R-C elements) using Z-View software. AC conductivity analyzed with Jonscher’s power law. Strain and polarization data used to calculate d33* and hysteresis.
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