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<p>This study used two-step sintering to prepare lead-free (1–<i>x</i>)[(K<sub>0.48</sub>Na<sub>0.48</sub>Li<sub>0.04</sub>)(Nb<sub>0.95</sub>Sb<sub>0.05</sub>)O<sub>3</sub>]– <i>x</i>BaZrO<sub>3</sub> [(1–<i>x</i>)KNNST–<i>x</i>BZ] ceramic samples with <i>x</i> = 0.0, 0.015, 0.03, 0.045, and 0.060. The influence of the content of BaZrO<sub>3</sub> (BZ) on the structure, microstructure, and physical properties of the (K<sub>0.48</sub>Na<sub>0.48</sub>Li<sub>0.04</sub>)(Nb<sub>0.95</sub>Sb<sub>0.05</sub>)O<sub>3</sub> (KNLNS) ceramic was studied in detail. Experimental results showed that the KNLNS crystal structure transformed from the orthorhombic phase to a rhombohedral phase to construct the new phase boundary near room temperature for 0.03 ≤ <i>x</i> ≤0.045, improving the electrical properties of the ceramic at the optimized BZ content. Raman scattering, X-ray diffraction, scanning electron microscopy, and the electrical properties of the samples showed that the optimal BZ content was 0.03&#xa0;mol, corresponding to the solubility limit of Ba<sup>2+</sup> and Zr<sup>4+</sup> ions in the KNLNS ceramics. Furthermore, substituting Ba<sup>2+</sup> and Zr<sup>4+</sup> at the A- and B-site induced lattice distortion in the (1–<i>x</i>)KNLNS– <i>x</i>BZ structure to increase the relaxation behavior and decrease the <i>T</i><sub>O−T</sub> values sharply to 45&#xa0;°C, which was the optimum poling condition that could develop the possible piezoelectric properties. At the optimized BZ content of 0.03&#xa0;mol, the 0.97KNNST– 0.03BZ ceramic had the best electrical properties: density = 4.56&#xa0;g/cm<sup>3</sup>, dielectric constant (<i>ε</i><sub>r</sub>) = 1130, electromechanical coupling factors <i>k</i><sub>p</sub> = 0.39 and <i>k</i><sub>t</sub> = 0.40, piezoelectric constant (<i>d</i><sub>33</sub>) = 225 pC/N, remanent polarization (<i>P</i><sub>r</sub>) = 15.2 µC/cm<sup>2</sup>, and normalized strain (<i>d</i><sub>33</sub><sup>*</sup>) = 470 pm/V. The highest <i>Q</i><sub>m</sub> value of 102 was for 0.045&#xa0;mol BZ.</p>

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The effect of BaZrO3 content on the structure, microstructure, and electrical properties of (K, Na)NbO3-based lead-free ceramics

  • 期刊论文

  • 发表日期：

    2025年4月18日

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  • Le Dai Vuong,
  • Ngo Xuan Cuong,
  • Nguyen Quang Lich,
  • Nguyen Dang Nhat,
  • Le Dinh Hieu,
  • Vo Quang Nha,
  • Le Tran Uyen Tu,
  • Le Van Tan,
  • Trinh Ngoc Dat

摘要

This study used two-step sintering to prepare lead-free (1–x)[(K0.48Na0.48Li0.04)(Nb0.95Sb0.05)O3]– xBaZrO3 [(1–x)KNNST–xBZ] ceramic samples with x = 0.0, 0.015, 0.03, 0.045, and 0.060. The influence of the content of BaZrO3 (BZ) on the structure, microstructure, and physical properties of the (K0.48Na0.48Li0.04)(Nb0.95Sb0.05)O3 (KNLNS) ceramic was studied in detail. Experimental results showed that the KNLNS crystal structure transformed from the orthorhombic phase to a rhombohedral phase to construct the new phase boundary near room temperature for 0.03 ≤ x ≤0.045, improving the electrical properties of the ceramic at the optimized BZ content. Raman scattering, X-ray diffraction, scanning electron microscopy, and the electrical properties of the samples showed that the optimal BZ content was 0.03 mol, corresponding to the solubility limit of Ba2+ and Zr4+ ions in the KNLNS ceramics. Furthermore, substituting Ba2+ and Zr4+ at the A- and B-site induced lattice distortion in the (1–x)KNLNS– xBZ structure to increase the relaxation behavior and decrease the TO−T values sharply to 45 °C, which was the optimum poling condition that could develop the possible piezoelectric properties. At the optimized BZ content of 0.03 mol, the 0.97KNNST– 0.03BZ ceramic had the best electrical properties: density = 4.56 g/cm3, dielectric constant (εr) = 1130, electromechanical coupling factors kp = 0.39 and kt = 0.40, piezoelectric constant (d33) = 225 pC/N, remanent polarization (Pr) = 15.2 µC/cm2, and normalized strain (d33*) = 470 pm/V. The highest Qm value of 102 was for 0.045 mol BZ.