研究目的
To investigate the sintering behavior and physical properties of Li2CO3-doped Bi0.5(Na0.8K0.2)0.5TiO3 lead-free ceramics, focusing on the effects of Li2CO3 addition and sintering temperature on phase structure, density, dielectric, ferroelectric, and piezoelectric properties.
研究成果
Li2CO3 doping improves the sinterability and physical properties of BNKT ceramics, with optimal results at 0.4 wt.% Li2CO3 and 1 100 °C sintering temperature, achieving high density, electromechanical coupling factors, remanent polarization, and dielectric constants. The phase structure changes from rhombohedral to tetragonal, indicating proximity to the morphotropic phase boundary.
研究不足
The study is limited to specific Li2CO3 contents and sintering temperatures; higher temperatures may cause Bi2O3 evaporation, reducing properties. The use of ultrasound milling may not be scalable for industrial applications, and the properties are optimized only for certain compositions.
1：Experimental Design and Method Selection:
The ceramics were fabricated using the conventional solid-state reaction method with ultrasound waves for preliminary milling to shorten processing time.
2：Sample Selection and Data Sources:
Samples were prepared with Li2CO3 content (x =
3：0, 2, 4, 6, 8 wt.%) and sintered at temperatures (1 000, 1 050, 1 100, 1 150 °C). Reagent grade oxide powders (Bi2O3, Na2CO3, K2CO3, Li2CO3, TiO2, purity ≥99%) were used. List of Experimental Equipment and Materials:
Equipment includes ultrasound treatment system (100 W, 28 kHz), ball mill, furnace for calcination and sintering, X-ray diffractometer (Rigaku RINT 2000), field emission scanning electron microscope (JSM-6340F), impedance analyzer (Agilent 4196B), RLC meter (HIOKI 3532), and ferroelectric loop measurement setup. Materials include ethanol for milling.
4：Experimental Procedures and Operational Workflow:
Weigh and mill starting materials with ultrasound in ethanol for 1 h, dry, calcine at 850 °C for 2 h, mix with Li2CO3, ball mill for 20 h, press into disks, sinter at specified temperatures for 2 h, pole samples in silicone oil at 120 °C with 30 kV cm–1 DC field for 20 min, age for 24 h, then characterize using XRD, SEM, density measurement, dielectric, ferroelectric, and piezoelectric tests.
5：Data Analysis Methods:
XRD for phase analysis, SEM for morphology, Archimedes method for density, resonance method for electromechanical coupling factors, Sawyer-Tower method for ferroelectric loops, and standard equations for calculating kp, kt, Qm.
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