水热法制备铌酸盐无铅压电陶瓷粉体及其性能研究

发布时间：2018-02-16 18:47

本文关键词： 铌酸盐无铅压电陶瓷水热法制备压电性能介电性能　出处：《陕西师范大学》2011年硕士论文　论文类型：学位论文

【摘要】：压电陶瓷是重要的功能材料,被广泛用于谐振器、滤波器、传感器等多种功能器件。然而,市场上占主导地位的锆钛酸铅(PZT)压电陶瓷含铅量超过70%,其生产和废弃处理过程中产生的铅污染会对人体和环境造成很大危害。为了保护环境和保证人类社会的可持续发展,人们一直在寻找可以替代PZT的无铅压电陶瓷。碱金属铌酸盐是重要的无铅压电陶瓷体系,其中KNbO3-NaNbO3(简称KNN)基无铅压电陶瓷以其压电性较高、铁电性能较强、居里温度高等特点而被认为是有望替代铅基陶瓷的材料。但是由于KNN陶瓷的压电性能对制备条件具有极强的敏感性,采用传统固相法很难得到结构致密和性能稳定的KNN陶瓷。目前的研究表明,水热法制备陶瓷粉体具有合成温度低、粉体活性高等特点,有望降低陶瓷的烧结温度,提高陶瓷的致密度和性能。本论文采用水热法和固相法分别合成了NaNbO3、KNbO3、(Na0.5K0.5)Nb03粉体,并制得相应的陶瓷。研究并对比了两种粉体的相结构、微观形貌以及相应陶瓷的电性能。 (1)采用水热法成功合成了大小均一、颗粒细小、高活性的正交相NaNbO3陶瓷粉体,通过对合成温度、碱浓度及保温时间的研究,发现水热法合成NaNbO3粉体的过程中,起始NaOH浓度和反应温度是关键因素。水热合成NaNbO3粉体的最佳条件为：NaOH浓度为2.64 M,Nb205浓度为0.66 M,反应温度为200℃,反应时间为24 h。同时采用固相法制备NaNbO3陶瓷粉体,对比研究了两种制备方法对粉体的相结构、微观形貌等的影响。通过对两种样品的EDS能谱分析和FTIR对比分析,验证了两种方法制备的粉体具有相同的化学成分。从Raman光谱看出,水热法制备的粉体为具有正交相O3相结构的小颗粒粉体(1μm),而固相法制备的粉体是具有正交相O1相结构的更大些的颗粒。对比两种粉体制成陶瓷的相结构和电性能,研究表明：水热陶瓷的最佳烧结温度为1340℃,相对密度高达98.7%；而固相陶瓷的最佳烧结温度为1360℃,相对密度为94.1%。水热陶瓷的介电常数,压电常数,机电耦合系数和相转变温度都要大于固相陶瓷的性能参数,其值为：d33=41 pC/N,Kp=0.30,εm=1565(1 kHz), Tc=378℃。 (2)采用水热法成功合成了KNbO3陶瓷粉体,研究了反应温度、起始KOH溶液浓度、反应时间对合成产物的影响规律,结果表明：KOH的浓度和反应温度是影响KNbO3粉体相结构和形貌的关键因素。当[Nb2O5]=0.33M,反应温度≥160℃,[OH]≥7M时,都可以合成纯相的KNbO3粉体。而且当KOH浓度为9 M,反应温度为180℃,反应时间为12 h,可以合成伪立方相的KNbO3。同时采用固相法制备了KNbO3陶瓷粉体,并采用两种粉体制成了陶瓷。水热陶瓷的最佳烧结温度为960℃,比固相陶瓷的烧结温度降低了30℃,陶瓷的烧结温区变宽,且两种陶瓷的相对密度基本相当。从介温图谱可以看出,水热陶瓷具有更高的介电常数,其值为11106,对应的从四方相到正交相的相变温度(居里温度)为424℃。 (3)采用水热NaNbO3、NaNbO3粉体合成了K0.5Na0.5NbO3(KNN)粉体,同时采用固相法制备KNN粉体,用传统烧结法制成陶瓷。研究了两种陶瓷的相结构、微观形貌和介电、压电性能。结果表明：水热陶瓷的最佳烧结温度为1070℃,比固相陶瓷的烧结温度低60℃,说明水热粉体具有较高的烧结活性。水热陶瓷的最大相对密度为3.77g/cm3,固相陶瓷的最大相对密度为4.01g/cm3。两种陶瓷的电性能接近,水热陶瓷的电性能为d33=100 pC/N,εm=4432, Tc=415℃。固相陶瓷的电性能为s33=96 pC/N,εm=4929,Tc=409℃。
[Abstract]:Piezoelectric ceramic is an important functional material, is widely used in resonator, filter function, sensors and other devices. However, the dominant lead zirconate titanate (PZT) piezoelectric ceramics lead content of more than 70%, the production and disposal of lead pollution generated in the process will cause great harm to the human body and the environment. In order to protect the environment and ensure the sustainable development of human society, people have been looking for alternatives to PZT lead-free piezoelectric ceramics.
Alkali Niobate Lead-free Piezoelectric Ceramics is an important system, in which KNbO3-NaNbO3 (KNN) lead-free piezoelectric ceramics with high piezoelectric properties, ferroelectric properties and higher temperature characteristics of Curie strong, is expected to replace the lead based ceramic materials. But due to the piezoelectric properties of KNN ceramics has strong sensitivity the preparation conditions, using the traditional solid state method is difficult to obtain compact structure and stable performance of the KNN ceramics. The present study showed that the hydrothermal preparation of ceramic powder has low synthesis temperature, high activity of the powder, is expected to reduce the sintering temperature of the ceramics, the ceramics density and improve performance.
In this paper, NaNbO3, KNbO3, (Na0.5K0.5) Nb03 powders were synthesized by hydrothermal method and solid phase method respectively, and the corresponding ceramics were prepared. The phase structure, microstructure and electrical properties of the two kinds of powders were compared.
(1) have been successfully synthesized by hydrothermal method with uniform size, fine particles, high activity of orthogonal phase NaNbO3 ceramic powder, through the synthesis of temperature of alkali concentration and soaking time, found that the hydrothermal synthesis of NaNbO3 powder in the process, the initial NaOH concentration and reaction temperature is the key factor. The best conditions hydrothermal synthesis of NaNbO3 powder: NaOH concentration was 2.64 M, the concentration of Nb205 was 0.66 M, the reaction temperature is 200 DEG C, the reaction time is 24 h. and the NaNbO3 ceramics prepared by solid phase powder, a comparative study of the two kinds of preparation methods of powder phase structure, microstructure and so on. Through the influence of of the two samples of EDS analysis and FTIR contrast spectrum, verified the powder prepared by two methods with the same chemical composition. Seen from the Raman spectra of powders prepared by hydrothermal method with orthogonal phase O3 small particle powder phase structure (1 m), and solid preparation the powder Body has orthorhombic O1 phase structure of larger particles. Studies show that comparing the two kinds of powder made of ceramic phase structure and electrical properties: the best sintering temperature of hot water is 1340 DEG C, relative density of up to 98.7%; and the optimum sintering temperature of ceramic phase is 1360 DEG C, the relative density of dielectric the dielectric constant 94.1%. hydrothermal ceramics, piezoelectric constant, electromechanical coupling coefficient and the performance parameters of the phase transition temperature was higher than solid ceramic, its value is: d33=41 pC/N, Kp=0.30, e m=1565 (1 kHz), Tc=378 C.
(2) the successful synthesis of KNbO3 ceramic powder by hydrothermal method. The effects of reaction temperature, initial concentration of KOH solution, effect of reaction time on the synthesis of the results showed that the concentration of KOH and reaction temperature are key factors influencing the phase structure and morphology of KNbO3 powder. When the reaction temperature is more than 160 [Nb2O5]=0.33M. C, [OH] = 7M, can synthesize KNbO3 powder and pure phase. When the KOH concentration is 9 M, the reaction temperature is 180 DEG C, the reaction time is 12 h, can be synthesized by pseudo cubic phase KNbO3. by solid phase method KNbO3 ceramic powders were synthesized, and using two kinds of powder made from ceramics hot water. The best sintering temperature is 960 DEG C, 30 degrees lower than the sintering temperature of solid ceramic, sintering temperature of ceramics becomes wider, and the relative density of two kinds of ceramics are quite basic. From the dielectric temperature map can be seen, ceramic hot water has higher dielectric constant, and its value is 11106, The corresponding phase transition temperature (Curie temperature) from the quadrature phase to the orthogonal phase is 424.
(3) by hydrothermal synthesis of K0.5Na0.5NbO3 NaNbO3, NaNbO3 powder (KNN) powder, and the preparation of KNN powder by solid phase method with traditional sintering method. The phase structure of ceramic two ceramics, microstructure and dielectric, piezoelectric properties. The results show that the optimum sintering temperature of hot water the 1070 degrees, 60 degrees lower than the sintering temperature of solid ceramic, sintering powder has higher hydrothermal activity. The maximum relative density of ceramic hot water is 3.77g/cm3, the maximum relative density of ceramic solid for the electric performance close to 4.01g/cm3. two ceramics, electrical properties of hydrothermal ceramic is d33=100 pC/N, e m=4432, Tc=415 C. The electrical properties of ceramic solid is s33=96 pC/N, e m=4929, Tc=409 C.

【学位授予单位】：陕西师范大学
【学位级别】：硕士
【学位授予年份】：2011
【分类号】：TM282

【参考文献】