KNN基無鉛壓電陶瓷的摻雜改性和微觀機理研究
發(fā)布時間：2018-09-11 17:59
【摘要】：鉛基壓電陶瓷在壓電領(lǐng)域有較廣泛的應(yīng)用,然而鉛元素的毒性限制了它的發(fā)展。隨著人們環(huán)保意識的增強,無鉛的堿性鈮酸鹽壓電材料得到了重點的關(guān)注。通過摻雜改性以及流延工藝制備出的鈮酸鹽系(KNN)壓電材料,具有可以與PZT(鉛基壓電陶瓷)相匹敵的性能。因此,制備高性能鈮酸鉀鈉等無鉛壓電陶瓷是現(xiàn)在的熱門研究課題。本文主要通過摻雜改性、兩步燒結(jié)以及流延法逐步提高KNN陶瓷壓電性能。陶瓷的兩相共存可以大大提高KNN基陶瓷的壓電性能,實驗采用CaTiO_3、BaTiO_3以及BaZrO_3復(fù)合摻雜,制備(0.91-x)K_(0.5)Na_(0.5)NbO_3-0.03BaTiO_3-0.06BaZrO_3-xCaTiO_3(簡寫為:(0.91-x)KNN-BT-BZ-xCT)。通過改變CaTiO_3摻量,使得陶瓷菱方-正交兩相共存區(qū)移向室溫附近,獲得陶瓷性能成倍提高。通過KNN相圖看出,由于堿金屬的存在,KNN陶瓷在燒結(jié)中容易使堿金屬揮發(fā),出現(xiàn)成分分凝,使得摻雜在液相區(qū)析出,導(dǎo)致陶瓷性能降低。實驗中采用兩步燒結(jié)法(TSS),有效的降低并阻止了分凝,減小晶粒,提高了陶瓷的成分均一化程度。為了進一步提高摻雜后陶瓷的性能,以片狀NN(NaNbO_3)作為模板,用流延法制備(001)面定向生長的0.90KNN-BT-BZ-0.01CT基陶瓷。通過三元系摻雜改性,當x取值0.01時,由于出現(xiàn)了準同型相界(PPT),(0.91-x)KNN-BT-BZ-xCT陶瓷的壓電和介電性能達到了最佳,為185PC/N。和SSS(普通固相法)燒結(jié)陶瓷相比,TSS燒結(jié)陶瓷的致密度要高出3%,壓電常數(shù)提高18%,為219 PC/N。通過XRD和EDS物相分析,TSS法燒結(jié)陶瓷物相具有更低的堿金屬燒損量。流延法中NN模板的制備至關(guān)重要,首先采用熔鹽法制備前驅(qū)體BNN,后又運用熔鹽法及產(chǎn)生的拓撲化學(xué)反應(yīng)制備了各向異性的片狀NaNbO_3模板晶粒。當模板含量為5%時,織構(gòu)壓電陶瓷材料性能達到最佳,制備陶瓷的織構(gòu)度f達到86%。和非織構(gòu)陶瓷相比,織構(gòu)陶瓷使得陶瓷的軸率(c/a)減小,介電溫譜曲線中居里溫度區(qū)域以及介電常數(shù)峰變窄,提高了陶瓷介電常數(shù)的溫度非線性。通過不同方法制備的壓電陶瓷中,織構(gòu)法制備的壓電陶瓷具有最佳的壓電常數(shù)和機電轉(zhuǎn)化效率,d33和Kp分別達到236PC/N和42.2%。
[Abstract]:Lead-based piezoelectric ceramics are widely used in piezoelectric field, however, the toxicity of lead element limits its development. With the increasing awareness of environmental protection, lead-free basic niobate piezoelectric materials have received great attention. The niobate series (KNN) piezoelectric materials prepared by doping modification and casting process have the properties of being comparable to those of PZT (lead based piezoelectric ceramics). Therefore, the preparation of lead-free piezoelectric ceramics such as potassium sodium niobate is a hot research topic. In this paper, the piezoelectric properties of KNN ceramics were improved by doping modification, two step sintering and casting method. The piezoelectric properties of KNN based ceramics can be greatly improved by the coexistence of two phases. (0.91-x) K _ (0.5) Na_ _ (0.5) NbO_3-0.03BaTiO_3-0.06BaZrO_3-xCaTiO_3 (abbreviated as (0.91-x) KNN-BT-BZ-xCT) was prepared by CaTiO_3,BaTiO_3 and BaZrO_3 doping. By changing the content of CaTiO_3, the coexisting region of rhombohedral and orthonormal phases is moved to the room temperature, and the properties of the ceramics are improved exponentially. The KNN phase diagram shows that the alkali metal is easily volatilized in the sintering process, and the component segregation occurs, which makes the doping precipitate in the liquid region, which results in the decrease of the ceramic properties. In the experiment, the two-step sintering method (TSS), can effectively reduce and prevent the segregation, reduce the grain size, and improve the homogenization of the ceramic composition. In order to further improve the properties of the doped ceramics, the (001) plane oriented 0.90KNN-BT-BZ-0.01CT based ceramics were prepared by using flake NN (NaNbO_3) as template. The piezoelectric and dielectric properties of the quasi homogeneous phase boundary (PPT), (0.91-x) KNN-BT-BZ-xCT ceramics were optimized when x value was 0. 01 by doping the ternary system, which was 185 PC / N. Compared with SSS sintered ceramics, the density of Sintered Ceramics is 3 times higher, and the piezoelectric constant is increased by 18 PC/N. to 219 PC/N.. By XRD and EDS phase analysis, the phase of ceramic sintered by TSS has lower alkali metal burning loss. The preparation of NN template is very important in the casting method. Firstly, the precursor BNN, is prepared by molten salt method, and then the anisotropic grain of NaNbO_3 template is prepared by molten salt method and topological chemical reaction. When the template content is 5, the properties of the textured piezoelectric ceramics are the best, and the textural degree f of the prepared ceramics is up to 86. Compared with the nonwoven ceramics, the axial ratio (c / a) of the ceramics decreases, the Curie temperature region and the dielectric constant peak in the dielectric temperature curve line become narrower, and the temperature nonlinearity of the dielectric constant is improved. Among the piezoelectric ceramics prepared by different methods, the textured piezoelectric ceramics have the best piezoelectric constant and electromechanical conversion efficiency (D33 and Kp) up to 236PC/N and 42.2, respectively.
【學(xué)位授予單位】：河南科技大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TM282
本文編號：2237435
[Abstract]:Lead-based piezoelectric ceramics are widely used in piezoelectric field, however, the toxicity of lead element limits its development. With the increasing awareness of environmental protection, lead-free basic niobate piezoelectric materials have received great attention. The niobate series (KNN) piezoelectric materials prepared by doping modification and casting process have the properties of being comparable to those of PZT (lead based piezoelectric ceramics). Therefore, the preparation of lead-free piezoelectric ceramics such as potassium sodium niobate is a hot research topic. In this paper, the piezoelectric properties of KNN ceramics were improved by doping modification, two step sintering and casting method. The piezoelectric properties of KNN based ceramics can be greatly improved by the coexistence of two phases. (0.91-x) K _ (0.5) Na_ _ (0.5) NbO_3-0.03BaTiO_3-0.06BaZrO_3-xCaTiO_3 (abbreviated as (0.91-x) KNN-BT-BZ-xCT) was prepared by CaTiO_3,BaTiO_3 and BaZrO_3 doping. By changing the content of CaTiO_3, the coexisting region of rhombohedral and orthonormal phases is moved to the room temperature, and the properties of the ceramics are improved exponentially. The KNN phase diagram shows that the alkali metal is easily volatilized in the sintering process, and the component segregation occurs, which makes the doping precipitate in the liquid region, which results in the decrease of the ceramic properties. In the experiment, the two-step sintering method (TSS), can effectively reduce and prevent the segregation, reduce the grain size, and improve the homogenization of the ceramic composition. In order to further improve the properties of the doped ceramics, the (001) plane oriented 0.90KNN-BT-BZ-0.01CT based ceramics were prepared by using flake NN (NaNbO_3) as template. The piezoelectric and dielectric properties of the quasi homogeneous phase boundary (PPT), (0.91-x) KNN-BT-BZ-xCT ceramics were optimized when x value was 0. 01 by doping the ternary system, which was 185 PC / N. Compared with SSS sintered ceramics, the density of Sintered Ceramics is 3 times higher, and the piezoelectric constant is increased by 18 PC/N. to 219 PC/N.. By XRD and EDS phase analysis, the phase of ceramic sintered by TSS has lower alkali metal burning loss. The preparation of NN template is very important in the casting method. Firstly, the precursor BNN, is prepared by molten salt method, and then the anisotropic grain of NaNbO_3 template is prepared by molten salt method and topological chemical reaction. When the template content is 5, the properties of the textured piezoelectric ceramics are the best, and the textural degree f of the prepared ceramics is up to 86. Compared with the nonwoven ceramics, the axial ratio (c / a) of the ceramics decreases, the Curie temperature region and the dielectric constant peak in the dielectric temperature curve line become narrower, and the temperature nonlinearity of the dielectric constant is improved. Among the piezoelectric ceramics prepared by different methods, the textured piezoelectric ceramics have the best piezoelectric constant and electromechanical conversion efficiency (D33 and Kp) up to 236PC/N and 42.2, respectively.
【學(xué)位授予單位】：河南科技大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TM282
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