研究目的
To improve the energy storage performance of lead-free AgNbO3-based antiferroelectric ceramics through La3+ modification, aiming for high recoverable energy density and efficiency.
研究成果
La3+ modification successfully stabilizes the antiferroelectric phase in AgNbO3 ceramics, reducing phase transition temperatures, decreasing remnant polarization, and increasing breakdown electric field, leading to a high recoverable energy density of 3.12 J/cm3 and efficiency of 0.63 at 230 kV/cm for x=0.02. This makes La-doped AgNbO3 a promising lead-free material for energy storage capacitors, with improvements attributed to reduced grain size and increased electrical resistivity.
研究不足
The study is limited to bulk ceramics; thin films or other forms were not explored. The solid solubility of La3+ in AgNbO3 is limited, leading to secondary phases at higher La contents (x>0.02), which may affect properties. The experiments were conducted at room temperature and specific electric fields; variations in temperature or field conditions were not extensively studied. Optimization of sintering conditions and scalability for industrial applications were not addressed.
1：Experimental Design and Method Selection:
Conventional solid-state reaction method was used to prepare Ag1-3xLaxNbO3 ceramics with varying La content. The rationale was to stabilize the antiferroelectric phase and enhance energy storage properties by reducing the tolerance factor through La3+ substitution.
2：Sample Selection and Data Sources:
Ceramics with compositions x=0, 0.005, 0.01, 0.02, 0.03, and 0.05 were prepared. Raw materials included high-purity Ag2O, La2O3, and Nb2O5 powders.
3：005, 01, 02, 03, and 05 were prepared. Raw materials included high-purity Ag2O, La2O3, and Nb2O5 powders.
List of Experimental Equipment and Materials:
3. List of Experimental Equipment and Materials: Equipment included ball mill for mixing, furnace for calcination and sintering, X-ray diffractometer (SmartLab-3kW, Rigaku Ltd.) for structural analysis, scanning electron microscope (FESEM SU8220, Hitachi Corp.) for microstructure observation, precision impedance analyzer (Agilent 4294A, Agilent Technologies) for dielectric and impedance measurements, and ferroelectric tester (RT66A, Radiant Technologies Inc.) for P-E loops, I-V curves, and breakdown strength measurements. Materials included Ag2O (≥99.7%), La2O3 (≥99.95%), Nb2O5 (≥99.99%), and PVA binder.
4：7%), La2O3 (≥95%), Nb2O5 (≥99%), and PVA binder.
Experimental Procedures and Operational Workflow:
4. Experimental Procedures and Operational Workflow: Powders were weighed, ball-milled in ethanol for 12 hours, dried, calcined at 900°C for 6 hours in O2 atmosphere, milled again, pressed into disks with PVA binder, binder burned out at 560°C for 3 hours, sintered at 1080-1120°C for 6 hours in O2 atmosphere. Samples were polished, coated with Ag electrodes, and subjected to XRD, SEM, dielectric, impedance, P-E, I-V, and breakdown measurements.
5：Data Analysis Methods:
XRD patterns were refined with Pbcm space group; dielectric and impedance data were analyzed for phase transitions and electrical properties; P-E loops were used to calculate energy storage density and efficiency; Arrhenius law was applied to impedance data for activation energy calculation.
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