Processing and Electrical Properties of KNbO₃ Ferroelectric Dense Ceramics Added with Small Amount of Bi₂O₃ and MnCO₃

Abstract:

Doping a small quantity of additive Bi2O3 is effective in suppressing the deliquescence of KNbO3 ceramics. When an optimized ball-milling process was included, dense and nondeliquescent KNbO3 ceramics were obtained by a conventional firing process. However, the presence of Bi prevented grain growth (<0.2 μm) and it was one of the causes of low ferroelectricity. Moreover, the insufficient resistivity made the poling treatment difficult. In order to improve the electric properties, a small quantity of additive MnCO3 was also doped into KNbO3 with 0.5 mass% Bi2O3. Codoping of KNbO3 with MnCO3 and Bi2O3 (abbreviated to KNBixMny; x = 0~1.0, y = 0~1.0 in mass%) improved the ferroelectricity of samples, and it also had an effect on the resistivity and densification of sintered bodies. Well-saturated P-E hysteresis loops were observed with any amount of Mn and the largest remanent polarization Pr was about 16 μC/cm2. The piezoelectric properties of KNBi0.5Mn0.3, which had the highest piezoelectricity in this study, are an electromechanical coupling factor k33 and piezoelectric constant d33 of 0.30 and 101 pC/N, respectively.

• Periodical: Key Engineering Materials (Volume 301)
• Pages: 19-22
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.301.19
• Online since: January 2006
• Authors: Takeru Yoshida, Hajime Nagata, Tadashi Takenaka
• Keywords: Ball-Milling Process, Ferroelectric, Lead-Free, Piezoelectric, Potassium Niobate

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