本文關(guān)鍵詞： 鈮酸鹽無鉛壓電陶瓷 水熱法制備 壓電性能 介電性能　出處：《陜西師范大學(xué)》2011年碩士論文　論文類型：學(xué)位論文

【摘要】：壓電陶瓷是重要的功能材料,被廣泛用于諧振器、濾波器、傳感器等多種功能器件。然而,市場上占主導(dǎo)地位的鋯鈦酸鉛(PZT)壓電陶瓷含鉛量超過70%,其生產(chǎn)和廢棄處理過程中產(chǎn)生的鉛污染會對人體和環(huán)境造成很大危害。為了保護(hù)環(huán)境和保證人類社會的可持續(xù)發(fā)展,人們一直在尋找可以替代PZT的無鉛壓電陶瓷。 堿金屬鈮酸鹽是重要的無鉛壓電陶瓷體系,其中KNbO3-NaNbO3(簡稱KNN)基無鉛壓電陶瓷以其壓電性較高、鐵電性能較強(qiáng)、居里溫度高等特點(diǎn)而被認(rèn)為是有望替代鉛基陶瓷的材料。但是由于KNN陶瓷的壓電性能對制備條件具有極強(qiáng)的敏感性,采用傳統(tǒng)固相法很難得到結(jié)構(gòu)致密和性能穩(wěn)定的KNN陶瓷。目前的研究表明,水熱法制備陶瓷粉體具有合成溫度低、粉體活性高等特點(diǎn),有望降低陶瓷的燒結(jié)溫度,提高陶瓷的致密度和性能。 本論文采用水熱法和固相法分別合成了NaNbO3、KNbO3、(Na0.5K0.5)Nb03粉體,并制得相應(yīng)的陶瓷。研究并對比了兩種粉體的相結(jié)構(gòu)、微觀形貌以及相應(yīng)陶瓷的電性能。 (1)采用水熱法成功合成了大小均一、顆粒細(xì)小、高活性的正交相NaNbO3陶瓷粉體,通過對合成溫度、堿濃度及保溫時間的研究,發(fā)現(xiàn)水熱法合成NaNbO3粉體的過程中,起始NaOH濃度和反應(yīng)溫度是關(guān)鍵因素。水熱合成NaNbO3粉體的最佳條件為：NaOH濃度為2.64 M,Nb205濃度為0.66 M,反應(yīng)溫度為200℃,反應(yīng)時間為24 h。同時采用固相法制備NaNbO3陶瓷粉體,對比研究了兩種制備方法對粉體的相結(jié)構(gòu)、微觀形貌等的影響。通過對兩種樣品的EDS能譜分析和FTIR對比分析,驗(yàn)證了兩種方法制備的粉體具有相同的化學(xué)成分。從Raman光譜看出,水熱法制備的粉體為具有正交相O3相結(jié)構(gòu)的小顆粒粉體(1μm),而固相法制備的粉體是具有正交相O1相結(jié)構(gòu)的更大些的顆粒。對比兩種粉體制成陶瓷的相結(jié)構(gòu)和電性能,研究表明：水熱陶瓷的最佳燒結(jié)溫度為1340℃,相對密度高達(dá)98.7%；而固相陶瓷的最佳燒結(jié)溫度為1360℃,相對密度為94.1%。水熱陶瓷的介電常數(shù),壓電常數(shù),機(jī)電耦合系數(shù)和相轉(zhuǎn)變溫度都要大于固相陶瓷的性能參數(shù),其值為：d33=41 pC/N,Kp=0.30,εm=1565(1 kHz), Tc=378℃。 (2)采用水熱法成功合成了KNbO3陶瓷粉體,研究了反應(yīng)溫度、起始KOH溶液濃度、反應(yīng)時間對合成產(chǎn)物的影響規(guī)律,結(jié)果表明：KOH的濃度和反應(yīng)溫度是影響KNbO3粉體相結(jié)構(gòu)和形貌的關(guān)鍵因素。當(dāng)[Nb2O5]=0.33M,反應(yīng)溫度≥160℃,[OH]≥7M時,都可以合成純相的KNbO3粉體。而且當(dāng)KOH濃度為9 M,反應(yīng)溫度為180℃,反應(yīng)時間為12 h,可以合成偽立方相的KNbO3。同時采用固相法制備了KNbO3陶瓷粉體,并采用兩種粉體制成了陶瓷。水熱陶瓷的最佳燒結(jié)溫度為960℃,比固相陶瓷的燒結(jié)溫度降低了30℃,陶瓷的燒結(jié)溫區(qū)變寬,且兩種陶瓷的相對密度基本相當(dāng)。從介溫圖譜可以看出,水熱陶瓷具有更高的介電常數(shù),其值為11106,對應(yīng)的從四方相到正交相的相變溫度(居里溫度)為424℃。 (3)采用水熱NaNbO3、NaNbO3粉體合成了K0.5Na0.5NbO3(KNN)粉體,同時采用固相法制備KNN粉體,用傳統(tǒng)燒結(jié)法制成陶瓷。研究了兩種陶瓷的相結(jié)構(gòu)、微觀形貌和介電、壓電性能。結(jié)果表明：水熱陶瓷的最佳燒結(jié)溫度為1070℃,比固相陶瓷的燒結(jié)溫度低60℃,說明水熱粉體具有較高的燒結(jié)活性。水熱陶瓷的最大相對密度為3.77g/cm3,固相陶瓷的最大相對密度為4.01g/cm3。兩種陶瓷的電性能接近,水熱陶瓷的電性能為d33=100 pC/N,εm=4432, Tc=415℃。固相陶瓷的電性能為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.

【學(xué)位授予單位】：陜西師范大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2011
【分類號】：TM282

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