Lead free (1<span style="white-space:nowrap;">−</span><em>x</em>)K<sub>0.5</sub>Na<sub>0.5</sub>NbO<sub>3</sub>-<em>x</em>Ca(...Lead free (1<span style="white-space:nowrap;">−</span><em>x</em>)K<sub>0.5</sub>Na<sub>0.5</sub>NbO<sub>3</sub>-<em>x</em>Ca(Zn<sub>1/3</sub>Nb<sub>2/3</sub>)O<sub>3</sub> (abbreviated KNN-xCZN) ferroelectric ceramics, with x = 0, 0.02, 0.04, 0.06, 0.08, 0.10, have been fabricated by the conventional solid-state reaction method. The effects of CZN content on the structure, microstructure and some optical, electrical properties of KNN-xCZN ceramics were studied in detail. The experimental results showed that the crystal structure of ceramics gradually transformed from orthorhombic phase into pseudo-cubic phase with doping of <em>x</em>Ca(Zn<sub>1/3</sub>Nb<sub>2/3</sub>)O<sub>3</sub>. With increasing of the CZN concentration, the ceramic density increased and reached the highest value (4.29 g/cm<sup>3</sup>) at <em>x</em> = 0.08 mol, besides, the grain size of the ceramics decreased gradually, the microstructure more uniform, the grains are packed with clear grain boundaries, fewer pores, especially at <em>x</em> = 0.08 mol. With the dense and fine-grained microstructures, the optical transmission of the ceramics is strong, the ceramic sample with <em>x</em> = 0.08 mol exhibits stably high transmittance above 60% in the visible spectrum and the largest optical band gap energy (<em>E<sub>g</sub></em> = 3.0 eV) was obtained. The Curie temperature (<em>T<sub>C</sub></em>) decreases when the concentration of CZN increases. The broadness of dielectric peaks around <em>T<sub>m</sub></em> indicated a diffusive phase transition for all compositions suggesting the relaxor-like behavior of KNN-xCZN ceramic systems.展开更多
文摘Lead free (1<span style="white-space:nowrap;">−</span><em>x</em>)K<sub>0.5</sub>Na<sub>0.5</sub>NbO<sub>3</sub>-<em>x</em>Ca(Zn<sub>1/3</sub>Nb<sub>2/3</sub>)O<sub>3</sub> (abbreviated KNN-xCZN) ferroelectric ceramics, with x = 0, 0.02, 0.04, 0.06, 0.08, 0.10, have been fabricated by the conventional solid-state reaction method. The effects of CZN content on the structure, microstructure and some optical, electrical properties of KNN-xCZN ceramics were studied in detail. The experimental results showed that the crystal structure of ceramics gradually transformed from orthorhombic phase into pseudo-cubic phase with doping of <em>x</em>Ca(Zn<sub>1/3</sub>Nb<sub>2/3</sub>)O<sub>3</sub>. With increasing of the CZN concentration, the ceramic density increased and reached the highest value (4.29 g/cm<sup>3</sup>) at <em>x</em> = 0.08 mol, besides, the grain size of the ceramics decreased gradually, the microstructure more uniform, the grains are packed with clear grain boundaries, fewer pores, especially at <em>x</em> = 0.08 mol. With the dense and fine-grained microstructures, the optical transmission of the ceramics is strong, the ceramic sample with <em>x</em> = 0.08 mol exhibits stably high transmittance above 60% in the visible spectrum and the largest optical band gap energy (<em>E<sub>g</sub></em> = 3.0 eV) was obtained. The Curie temperature (<em>T<sub>C</sub></em>) decreases when the concentration of CZN increases. The broadness of dielectric peaks around <em>T<sub>m</sub></em> indicated a diffusive phase transition for all compositions suggesting the relaxor-like behavior of KNN-xCZN ceramic systems.
