Park Yeon-Ju, Yoo Il-Ryeol, Choi Seong-Hui, Cho Jiung, Cho Kyung-Hoon
School of Materials Science and Engineering, Kumoh National Institute of Technology, Gumi 39177, Korea.
Western Seoul Center, Korea Basic Science Institute, Seoul 03579, Korea.
Materials (Basel). 2022 Mar 22;15(7):2357. doi: 10.3390/ma15072357.
This study investigated the causes of microstructural changes and the resultant electrical properties according to the sintering temperature of 0.96(KNa)NbSbO-0.04Bi(NaK)ZrO lead-free ceramics by analyzing the correlation between vacancy concentrations and 2D nucleation. When sintered for 4 h, no grain growth occurred for the x = 0.000 composition over a wide temperature range, demonstrating that the existence of initial vacancies is essential for grain growth. As x increased, that is, as the vacancy concentration increased, the critical driving force (ΔG) for 2D nucleation decreased, and abnormal grain growth was promoted. The number and size of these abnormal grains increased as the sintering temperature increased, but at sintering temperatures above 1100 °C, they decreased again owing to a large drop in ΔG. The x = 0.005 specimen sintered at 1085 °C exhibited excellent piezoelectric properties of d = 498 pC/N and k = 0.45 due to the large number of large abnormal grains with an 83% tetragonal phase fraction. The x = 0.000 specimen sintered at 1130 °C with suppressed grain growth exhibited good energy storage properties because of its very high relative density and small grain size of 300 to 400 nm.
本研究通过分析空位浓度与二维形核之间的相关性，研究了0.96(KNa)NbSbO-0.04Bi(NaK)ZrO无铅陶瓷在不同烧结温度下微观结构变化的原因及其产生的电学性能。当烧结4小时时，x = 0.000组成在很宽的温度范围内均未发生晶粒生长，这表明初始空位的存在对晶粒生长至关重要。随着x的增加，即空位浓度增加，二维形核的临界驱动力(ΔG)降低，促进了异常晶粒生长。这些异常晶粒的数量和尺寸随着烧结温度的升高而增加，但在烧结温度高于1100°C时，由于ΔG大幅下降，它们又会减少。在1085°C烧结的x = 0.005试样由于大量具有83%四方相分数的大异常晶粒而表现出优异的压电性能，d = 498 pC/N，k = 0.45。在1130°C烧结且晶粒生长受到抑制的x = 0.000试样由于其非常高的相对密度和300至400 nm的小晶粒尺寸而表现出良好的储能性能。
