首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到10条相似文献,搜索用时 31 毫秒
1.
BNT-BT和BNT-BKT基无铅压电陶瓷研究进展   总被引:5,自引:1,他引:5  
陈志武 《材料导报》2006,20(1):14-18
综述了Bi0.5Na0.5TiO3-BaTiO3系和Bi0.5Na0.5TiO3-Bi0.5K0.5TiO3系无铅压电陶瓷的最新研究进展.总结了各种添加剂对这两种无铅压电陶瓷体系压电性能的影响机理和规律,介绍了当前以各种工艺对其微观结构和压电性能进行改进的研究成果,并展望了这两种无铅压电陶瓷体系的发展趋势.  相似文献   

2.
徐华  沈明荣  方亮  甘肇强 《功能材料》2004,35(5):603-605,609
采用脉冲激光沉积法,在Pt/Ti/SiO2/Si基底上分剐制备厚度为350nm的Ba0.5Sr0.5TiO3(BST)、Pb0.5Ba0.5TiO3(PBT)和Pb0.5Sr0.5TiO3(PST)薄膜并研究了它们的介电性质。XRD显示,在相同的制备条件下三者具有不同的择优取向,PST具有(110)择优取向,PBT具有(111)择优取向,而BST则是混合取向。SEM显示三者样品表面均匀致密,颗粒尺寸大约在50nm至150nm之间。PST与BST、PBT相比有更高的介电常数,在频率为10kHz时,分别为874、334和355,而损耗都较低,分别为0.0378、0.0316和0.0423,同时PST漏电流也是最小的。测量薄膜的C-V特性扣铁电性能表明室温下BST呈现的是顺电相,PST和PBT则呈铁电相。本文也测量了薄膜在不同频率下的介电温度特性,BST、PBT和PST均表现出频率弥散现象,即随着频率的降低.居里温度降低而介电常数会升高。并测得BST和PST的居里温度分剐为-75和150℃。而PBT的居里温度在250℃以上。本文研究表明:与BST相比较,PBT的介电常数与之相近,漏电流较大;而PST具有高介电常数,较小的漏电流和较大的电容-电压调谐度,在相关半导体器件中的应用将有很大的潜力。  相似文献   

3.
Nanocrystalline powders of K0.5Na0.5NbO3 (KNN) and 0.9Na0.5K0.5NbO3–0.1Bi0.5Na0.5TiO3 (KNN–BNT) have been prepared using a low-temperature solid-state reaction. Phase development of the powders incurred during various calcination temperatures was examined by X-ray diffraction (XRD). Crystallite size and particle morphology of KNN powders were examined by XRD and transmission electron microscopy, respectively. Perovskite phase was formed at the temperature as low as 500 °C, and the average crystallite size of KNN powders depended on calcination temperature. In addition, the crystalline structure of KNN powders tended to change from tetragonal symmetry to orthorhombic symmetry with increase in crystallite size. Similar results were obtained in KNN–BNT system. The developed method is well suited for the mass production of niobate nanocrystalline powders due to its simplicity and low cost.  相似文献   

4.
5.
采用传统的干压成型法制备了Na0.5Bi0.5TiO3-K0.5Bi0.5TiO3无铅压电陶瓷,研究了不同K0.5Bi0.5TiO3含量对Na0.5Bi0.5TiO3-K0.5Bi0.5TiO3陶瓷的微观结构与电性能的影响规律.结果表明,Na0.5Bi0.5TiO3-K0.5Bi0.5TiO3无铅压电陶瓷随K0.5Bi0.5TiO3含量增加,晶格常数增大,密度减小,晶粒尺寸减小,压电常数先增大后减小,介电常数增大,介电损耗增加,机械品质因数下降,而居里温度不断升高,在200℃附近存在由铁电相向反铁电相转变的一个相变点,组分为0.84 Na0.5Bi0.5TiO3-0.16 K0.5Bi0.5TiO3的陶瓷位于准同型相界附近,具有最佳的压电性能.  相似文献   

6.
We have carried out systematic investigations in perovskite multiferroic La0.5Bi0.5Mn0.5Fe0.5O3 by means of X-ray diffraction, magnetisation, electrical resistivity, thermoelectric and heat capacity measurements. The magnetic behaviour of this composition is rather complex, though the magnetisation curve seems to be like a weak ferromagnetic material. However, there is no clear evidence of λ-anomaly in the heat capacity data down to 2 K, yet this behaviour corroborate the trends of semiconducting silicon below room temperature. The sensitivity of magnetic behaviour to the iron-manganese ratio is also demonstrated. In presence of an external field of 7 T, it exhibits a magnetoresistance of ?5 % at 130 K. The thermoelectric value increases linearly with decreasing temperature, and at room temperature the value is +85 μV/K, which is associated with the p-type polaronic conductivity.  相似文献   

7.
Na0.5 Bi0.5 TiO3-K0.5 Bi0.5 TiO3系铁电体的相变研究   总被引:1,自引:0,他引:1  
研究了(Na1-xKx)0.5Bi0.5TiO3体系x分别为0、0.08、0.16和0.20时陶瓷不同频率下的介电温谱,发现材料为弛豫型铁电体,材料的介电谱在室温到500℃的温度范围内存在一个介电常数-温度"台阶",一个介电常数-温度峰和一个介电损耗-温度峰,通过分析陶瓷不同温度下的电滞回线验证陶瓷在升温过程中产生了铁电-反铁电-顺电相变,采用铁电体成分起伏理论和内电场理论解释了这类弛豫型铁电体相变的原因.  相似文献   

8.
Lead-free (1−x) K0.5Na0.5NbO3–xBi0.5Li0.5TiO3 + 1 mol% MnO2 piezoelectric ceramics have been prepared by a conventional ceramic technique and their structure and piezoelectric properties have been studied. Our results reveal that Bi0.5Li0.5TiO3 diffuse into K0.5Na0.5NbO3 lattices to form a solid solution with a perovskite structure. The addition of Bi0.5Li0.5TiO3 to the K0.5Na0.5NbO3 solid solution decreases the paraelectric cubic-ferroelectric tetragonal phase transition temperature (T C) slightly, but shifts the ferroelectric tetragonal-ferroelectric orthorhombic phase transition temperature (T O−T) significantly to low temperatures. As a result, coexistence of the orthorhombic and tetragonal phases is formed at 0.01 < x < 0.03 near room temperature, leading to a significant improvement in the piezoelectric properties of the ceramics. The ceramic with x = 0.025 exhibits a relatively high T C (392 °C) and optimum piezoelectric properties: d 33 = 191 pC/N, k p = 51.5% and k t = 45.5%. The ceramic also exhibit a good thermal stability of piezoelectric properties.  相似文献   

9.
(1 − x)Bi0.5Na0.5TiO3xBi0.5Li0.5TiO3 lead-free ceramics have been prepared by a conventional solid-state reaction method, and their piezoelectric and dielectric properties have been studied. X-ray diffraction studies reveal that Li+ diffuses into the Bi0.5Na0.5TiO3 lattices to form a solid solution with a pure perovskite structure. The addition of Bi0.5Li0.5TiO3 effectively lowers the sintering temperature of the ceramics and greatly assists in the densification of the ceramics. The ceramic with x = 0.075 possesses the optimum piezoelectric properties: piezoelectric coefficient d 33 = 121 pC/N and planar electromechanical coupling factor k P = 18.3%. After the partial substitution of Li+ for Na+ in the A-sites of Bi0.5Na0.5TiO3, the ceramics exhibit more relaxor characteristic, which is probably resulted from the cation disordering in the 12-fold coordination sites. The depolarization temperature T d shifts to low temperature with the substitution level x of Li+ for Na+ increasing.  相似文献   

10.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号