Abstract
In this paper, sodium potassium niobate (KNN) lead-free piezoelectric ceramic powders were synthesized by the hydrothermal method using KOH, NaOH, Nb2O5 as raw materials, and the lead-free piezoelectric ceramics were prepared by the pressureless sintering method. Also, The KNN piezoelectric powders and ceramics were prepared by the conventional solid-state reaction method using K2CO3, Na2CO3, and Nb2O5as raw materials. The structures and properties of the KNN powders and ceramics were studied by the X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS), precision impedance analyzer (PIA), and so on.
First of all，the hydrothermal synthesis conditions of NaNbO3 and KNbO3 powders were studied. For the NaNbO3 powders, the optimum hydrothermal synthesis conditions are as follows: the reaction temperature of 200℃, the filling degree of 60%, the Nb2O5 concentration of 0.125mol/L, the NaOH concentration of 2-5 mol/L, and reaction time of at least 6 hours. The KNbO3 powders could be synthesized in the appropriate hydrothermal conditions of reaction temperature of 220℃, the filling degree of 60%, the KOH concentration of 10mol/L, the Nb2O5 concentration of 0.125mol/L and reaction time of 24 hours.
魁蒿The phase structure of the KNN ceramic powders synthesized by hydrothermal method was studied. It has been shown that it is easy to synthesis the K-rich or Na-rich KNN limited solid solution. However, it is hard to get the single phase K0.5Na0.5NbO3 solid solution. Experimental results showed that when the K/Na molar ratio of the original solution is near 4.5, an intermediate state of two-phase coexistence could be observed in the XRD patterns. However, a single solid solution phase structure was formed in all of the other K/Na molar ratios of the original solution. When K/Na>4.5, a K-rich-based KNN limited solid solution (K-KNN) was formed. When K/Na<4.5, a Na-rich based KNN limited solid (Na-KNN) was formed. The product with two-phase coexistence was formed as K/Na=4.5.
The solid-state synthesis technique of the KNN powders was also studied and results showed that the KNN powders with good performance could be obtained by calcining the prepared powder at 840℃.
The effects of the sintering temperature, polarization voltage and polarization time on
the piezoelectric and the dielectric properties of the KNN ceramics were investigated. In the range of 1000-1060℃, with the increase of sintering temperature, the piezoelectric and dielectric constant of t
he KNN ceramics increased. With the increase of the polarization voltage, the piezoelectric constant of the KNN ceramic was improved. With the increase of the polarization time, the dielectric constant of the KNN ceramics showed a decreasing trend. Compared the KNN ceramics without polarization, the dielectric constant of the polarized KNN ceramics decreased obviously.
The optimum electrical properties of the KNN ceramics by using the solid-state reaction synthesized powders are: d33 = 126 pC/N, Q m = 62.4202, K p = 0.5533, εr = 460.917. And the optimum electrical properties of the KNN ceramics by using the hydrothermal method synthesized powders are: d33 = 74Pc/N, εr = 613.434.
Key Words: lead-free piezoelectric ceramics; (K,Na)NbO3 (KNN); hydrothermal method; solid-state method; properties
马艺文
目录目录
第一章第一章 绪论 (1)
1.1 1.1 引言 (1)
1.2.1 1.2.1 压电效应与压电常数压电效应与压电常数 (1)
1.2.2 1.2.2 压电性与晶体结构 (2)
1.2.3 1.2.3 压电性与张量 (2)
1.2.4 1.2.4 压电材料研发历程 (3)
1.2.5 1.2.5 常用压电陶瓷的性能参数常用压电陶瓷的性能参数 (4) 1.2.6 1.2.6 压电材料的应用 (5)
1.3 1.3 无铅压电陶瓷国内外研究现状 (6)
1.3.1 1.3.1 无铅压电陶瓷的提出及研究意义无铅压电陶瓷的提出及研究意义 (6)
1.3.2 1.3.2 无铅压电陶瓷的研究体系无铅压电陶瓷的研究体系 (6)
1.3.3 KNN 基无铅压电陶瓷研究现状 (9)
1.4 1.4 主要研究内容主要研究内容........................................................................................................14 参考文献.. (15)
第二章第二章 实验过程与研究方法实验过程与研究方法 (17)
梁自强
2.1 主要原料和实验仪器 (17)
2.2 实验过程及方案 (18)
2.2.1 .2.1 水热法制备水热法制备KNN 陶瓷粉体陶瓷粉体 (18) 2.2.2 2.2.2 固相法制备固相法制备KNN 陶瓷粉体陶瓷粉体 (18)
挠度计算公式2.2.3 2.2.3 粉体制备压电陶瓷粉体制备压电陶瓷 (21)
2.3 材料表征和性能测试 (27)
2.3.1 X 射线衍射分析射线衍射分析 (27) 2.3.2 2.3.2 扫描电子显微镜扫描电子显微镜扫描电子显微镜(SEM)(SEM)(SEM)和能谱和能谱和能谱（（EDS EDS））分析分析 (28)
2.3.3 2.3.3 压电常数压电常数d 33分析分析 (28)
2.3.4 2.3.4 介电常数介电常数ε分析 (28)
2.3.5 2.3.5 机电耦合系数机电耦合系数Kp 和机械品质因数Qm 分析分析..............................................28 参考文献 (29)
第三章第三章 水热法制备水热法制备KNN 陶瓷粉体及其表征 (30)
3.1 3.1 前言前言 (30)
3.2 NaNbO 3的制备与表征的制备与表征 (30)
3.2.1 NaNbO 3的制备的制备 (30)
3.2.2 3.2.2 不同不同NaOH 浓度下合成NaNbO 3的XRD 分析 (31)
3.3 KNbO 3的制备与表征的制备与表征 (32)
3.3.1 KNbO 3粉体制备条件粉体制备条件 (32)
3.3.2 3.3.2 粉体的粉体的XRD 分析 (32)
吴新谋3.33.3.3 KNbO .3 KNbO 3的SEM 和EDS 分析分析 (34)
3.4 3.4 水热合成水热合成KNN 粉体与表征 (35)
3.4.1 3.4.1 原始溶液中原始溶液中K/Na=3时不同反应时间下产物的XRD 分析分析 (36)
3.4.2 3.4.2 不同反应时间下的不同反应时间下的SEM 分析分析 (36)
3.4.3 3.4.3 不同不同K/Na 摩尔比时所得KNN 的XRD 分析分析 (37)
3.4.4 3.4.4 不同不同K/Na 摩尔比时所得KNN 的SEM 分析分析 (38)
3.4.5 3.4.5 不同不同K/Na 摩尔比时所得KNN 的EDS 分析分析 (40)
3.5 Sm 2O 3、B 2O 3掺杂对水热合成KNN 的形貌和相结构的影响 (42)
3.5.1 3.5.1 掺杂掺杂Sm 2O 3的X RD 分析分析 (42)
3.5.2 3.5.2 掺杂掺杂Sm 2O 3的SEM 和EDS 分析分析 (43)
3.5.3 3.5.3 掺杂掺杂B 2O 3的XRD 和SEM 分析分析 (44)
脂松香3.6 KNN 晶体结构分析晶体结构分析 (44)
3.7 3.7 本章小结本章小结................................................................................................................46 参考文献.. (47)
第四章第四章 KNN KNN 无铅压电陶瓷相结构与电学性能研究 (49)
4.1 4.1 原材料的基本性能原材料的基本性能 (49)
4.2 KNN 的相结构分析的相结构分析 (51)
4.2.1 4.2.1 固相法制备固相法制备KNN 粉体的XRD 分析分析 (51)
4.2.2 4.2.2 水热法制备水热法制备KNN 粉体的XRD 分析分析 (51)
4.2.3 4.2.3 不同方法制备的粉体对不同方法制备的粉体对KNN 陶瓷相结构的影响陶瓷相结构的影响 (52)
4.2.44.2.4 不同烧结工艺对不同烧结工艺对KNN 陶瓷相结构的影响陶瓷相结构的影响 (53)
4.2.5 4.2.5 添加添加Sb 2O 3对KNN 陶瓷相结构的影响陶瓷相结构的影响 (54)
4.3 KNN 陶瓷的SEM 分析分析 (55)
4.3.1 4.3.1 不同粉体烧结不同粉体烧结KNN 陶瓷的SEM 分析分析 (55)
4.3.2 4.3.2 不同工艺烧结不同工艺烧结KNN 陶瓷的SEM 分析分析 (56)
4.3.3 4.3.3 添加添加Sb 2O 3烧结KNN 陶瓷的SEM 分析分析 (57)
4.4 KNN 陶瓷的电学性能分陶瓷的电学性能分 (57)
4.3.1 4.3.1 烧结温度对陶瓷电性能的影响烧结温度对陶瓷电性能的影响烧结温度对陶瓷电性能的影响 (60)
4.3.2 4.3.2 极化电压对陶瓷电性能影响极化电压对陶瓷电性能影响极化电压对陶瓷电性能影响 (61)
4.5 本章小结................................................................................................................62 参考文献..........................................................................................................................63 结论与展望....................................................................................................................64 致 谢谢. (66)
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