水热法制备BNT无铅压电陶瓷及性能研究
发布时间：2018-07-23 12:41
【摘要】：随着人们对环境保护的重视,无铅压电陶瓷作为压电陶瓷中的“后起之秀”,正在逐渐得到研究人员的重视。对于无铅压电陶瓷的深入研究,使得无铅压电陶瓷有望替代以PZT基陶瓷为主的含铅压电陶瓷,这样不仅会降低有毒铅的使用和排放,还可以实现绿色制造和绿色应用,对于生态环境的可持续发展产生重要推动作用。水热法属于一种高效率液相化学合成法。与传统的固相法及其他方法相比较,水热法有很多优势,例如,水热法获得的陶瓷纳米晶粒径小、尺寸比较均匀、反应温度低等。因此,水热法是制备压电陶瓷纳米晶的首选方法。本文采用水热法,通过控制矿化剂NaOH的浓度和水热反应时间,成功制备出了片状、立方块状和线状等不同形貌的Na0.5Bi0.5TiO3(BNT)纳米晶,并描述了不同形貌BNT纳米晶的生长机理。研究了不同形貌BNT纳米晶烧结成的BNT陶瓷的组织、形貌和电学性能,并分析了不同烧结温度对BNT压电陶瓷性能的影响。本文基于纳米晶形核及热力学分析,利用原位自组装和溶解再结晶机制,描述了不同形貌BNT纳米晶的生长行为和生长机理。其主要的生长行为是:当NaOH浓度较低时,c轴方向的生长速度严重慢于a和b轴。纳米晶沿着择优取向方向生长(a/b轴),从而有利于形成片状BNT纳米晶;随着NaOH浓度增加,溶解再结晶机制会加速并主导生长过程,容易形成立方块状BNT纳米晶;BNT纳米线的的生长不仅受NaOH浓度的影响,同时需要一个较长的反应时间;得出NaOH的浓度对于BNT纳米晶的形貌起着至关重要的作用。本文利用不同形貌的BNT纳米晶烧制了Na0.5Bi0.5TiO3压电陶瓷,通过对陶瓷组织形貌和电学性能对比分析,发现利用片状BNT纳米晶烧结的陶瓷相对最致密,且晶粒较大,组织形貌均一,说明BNT纳米晶的形貌对其陶瓷烧结体的组织有影响,片状BNT纳米晶有助于晶粒的生长。由片状BNT纳米晶烧制的陶瓷的电学性能相对最好,烧成的陶瓷有较高的剩余极化强度和较高的介电系数,其压电系数d33可达87pC/N,这要好于其他文献中所报道的BNT体系的压电性能。通过研究不同烧结温度对片状BNT纳米晶烧成陶瓷性能的影响,发现烧结温度在1150℃时,陶瓷相对较为致密,BNT陶瓷的电学性能相对最好,从而确定1150℃为最佳烧结温度。
[Abstract]:With the importance of environmental protection, lead-free piezoelectric ceramics, as a "rising star" of piezoelectric ceramics, are being paid more and more attention by researchers. With the further study of lead-free piezoelectric ceramics, lead-free piezoelectric ceramics are expected to replace lead-based piezoelectric ceramics, which not only reduce the use and emission of toxic lead, but also achieve green manufacturing and green applications. It plays an important role in promoting the sustainable development of ecological environment. Hydrothermal method belongs to a high efficient liquid phase chemical synthesis method. Compared with traditional solid phase method and other methods, hydrothermal method has many advantages, for example, the size of ceramic nanocrystals obtained by hydrothermal method is small, the size is uniform, and the reaction temperature is low. Therefore, hydrothermal method is the preferred method for the preparation of piezoelectric nanocrystals. In this paper, by controlling the concentration of mineralizer NaOH and hydrothermal reaction time, Na0.5Bi0.5TiO3 (BNT) nanocrystals with different morphologies, such as flake, cubic and linear, were successfully prepared by hydrothermal method. The growth mechanism of BNT nanocrystals with different morphologies was described. The microstructure, morphology and electrical properties of BNT ceramics sintered with different morphologies of BNT nanocrystals were studied, and the effects of sintering temperature on the properties of BNT piezoelectric ceramics were analyzed. Based on the nucleation of nanocrystalline and thermodynamic analysis, the growth behavior and mechanism of BNT nanocrystals with different morphologies were described by in situ self-assembly and dissolution recrystallization. The main growth behavior is that when the concentration of NaOH is low, the growth rate in the direction of C axis is slower than that in axis a and b. The nanocrystals grow along the preferred orientation (a / b axis), thus facilitating the formation of flake BNT nanocrystals. With the increase of NaOH concentration, the mechanism of dissolution and recrystallization accelerates and dominates the growth process. The growth of cubic bulk BNT nanocrystalline nanowires is affected not only by the concentration of NaOH, but also by a long reaction time. It is concluded that the concentration of NaOH plays an important role in the morphology of BNT nanocrystals. In this paper, Na0.5Bi0.5TiO3 piezoelectric ceramics were sintered with BNT nanocrystals with different morphologies. By comparing the microstructure and electrical properties of the ceramics, it was found that the ceramics sintered by BNT nanocrystals were the densest, with larger grains and uniform microstructure. The results show that the morphology of BNT nanocrystals has an effect on the microstructure of the sintered ceramics, and the flake BNT nanocrystals are helpful to the growth of the grains. The ceramic sintered with flake BNT nanocrystals has the best electrical properties. The sintered ceramics have higher residual polarization strength and higher dielectric coefficient. The piezoelectric coefficient d33 can reach 87pC / N, which is better than the piezoelectric properties of BNT system reported in other literatures. The effect of sintering temperature on the properties of BNT nanocrystalline sintered ceramics was studied. It was found that when sintering temperature was 1150 鈩，
本文编号：2139444
[Abstract]:With the importance of environmental protection, lead-free piezoelectric ceramics, as a "rising star" of piezoelectric ceramics, are being paid more and more attention by researchers. With the further study of lead-free piezoelectric ceramics, lead-free piezoelectric ceramics are expected to replace lead-based piezoelectric ceramics, which not only reduce the use and emission of toxic lead, but also achieve green manufacturing and green applications. It plays an important role in promoting the sustainable development of ecological environment. Hydrothermal method belongs to a high efficient liquid phase chemical synthesis method. Compared with traditional solid phase method and other methods, hydrothermal method has many advantages, for example, the size of ceramic nanocrystals obtained by hydrothermal method is small, the size is uniform, and the reaction temperature is low. Therefore, hydrothermal method is the preferred method for the preparation of piezoelectric nanocrystals. In this paper, by controlling the concentration of mineralizer NaOH and hydrothermal reaction time, Na0.5Bi0.5TiO3 (BNT) nanocrystals with different morphologies, such as flake, cubic and linear, were successfully prepared by hydrothermal method. The growth mechanism of BNT nanocrystals with different morphologies was described. The microstructure, morphology and electrical properties of BNT ceramics sintered with different morphologies of BNT nanocrystals were studied, and the effects of sintering temperature on the properties of BNT piezoelectric ceramics were analyzed. Based on the nucleation of nanocrystalline and thermodynamic analysis, the growth behavior and mechanism of BNT nanocrystals with different morphologies were described by in situ self-assembly and dissolution recrystallization. The main growth behavior is that when the concentration of NaOH is low, the growth rate in the direction of C axis is slower than that in axis a and b. The nanocrystals grow along the preferred orientation (a / b axis), thus facilitating the formation of flake BNT nanocrystals. With the increase of NaOH concentration, the mechanism of dissolution and recrystallization accelerates and dominates the growth process. The growth of cubic bulk BNT nanocrystalline nanowires is affected not only by the concentration of NaOH, but also by a long reaction time. It is concluded that the concentration of NaOH plays an important role in the morphology of BNT nanocrystals. In this paper, Na0.5Bi0.5TiO3 piezoelectric ceramics were sintered with BNT nanocrystals with different morphologies. By comparing the microstructure and electrical properties of the ceramics, it was found that the ceramics sintered by BNT nanocrystals were the densest, with larger grains and uniform microstructure. The results show that the morphology of BNT nanocrystals has an effect on the microstructure of the sintered ceramics, and the flake BNT nanocrystals are helpful to the growth of the grains. The ceramic sintered with flake BNT nanocrystals has the best electrical properties. The sintered ceramics have higher residual polarization strength and higher dielectric coefficient. The piezoelectric coefficient d33 can reach 87pC / N, which is better than the piezoelectric properties of BNT system reported in other literatures. The effect of sintering temperature on the properties of BNT nanocrystalline sintered ceramics was studied. It was found that when sintering temperature was 1150 鈩，
本文编号：2139444
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