【摘要】：隨著在(Na0.5Bi0.5)TiO3 (BNT)體系以及其它鉍基鈣鈦礦體系中大的電致應(yīng)變現(xiàn)象的發(fā)現(xiàn),鉍基鈣鈦礦體系應(yīng)變性能的研究逐漸成為近年來(lái)的研究熱點(diǎn)。然而,目前鉍基鈣鈦礦體系的研究還存在諸多問(wèn)題：如已有的研究主要針對(duì)BNT-BaTiO3/(K0.5Bi0.5)TiO3 (BT/KBT)二元體系或以此為基體制備的三元體系展開(kāi),對(duì)其它BNT體系或其它鉍基鈣鈦礦體系的研究相對(duì)較少；這些體系只能在較高的電場(chǎng)下才能獲得大應(yīng)變；這些體系中獲得的應(yīng)變都具有明顯的組成和溫度依賴特性以及較大的應(yīng)變滯后；鉍基鈣鈦礦體系大應(yīng)變的產(chǎn)生機(jī)理及應(yīng)變產(chǎn)生的具體過(guò)程還不是很清楚等等。針對(duì)上述問(wèn)題,本論文主要選取不同的鉍基鈣鈦礦體系進(jìn)行對(duì)比研究及相應(yīng)的組成優(yōu)化設(shè)計(jì),顯著地改善了上述鉍基鈣鈦礦體系應(yīng)變性能的不足,獲得了具有優(yōu)異應(yīng)變特性的鉍基鈣鈦礦陶瓷；基于多種測(cè)試手段,深入研究了不同體系中組成、結(jié)構(gòu)、性能之間的相互關(guān)系,對(duì)鉍基鈣鈦礦體系大應(yīng)變的產(chǎn)生機(jī)理及應(yīng)變性能的調(diào)節(jié)機(jī)理作了進(jìn)一步深入研究。全文主要研究?jī)?nèi)容如下：(1)在BNT-PbTiO3基礎(chǔ)之上,利用Bi(Mg0.5Ti0.5)O3取代BNT,研究了BNT-PbTiO3-xBi(Mg0.5Ti0.5)O3 (BNT-PT-xBMT)三元體系的相結(jié)構(gòu)及電學(xué)性能的變化。研究發(fā)現(xiàn),隨BMT含量的增加,該體系的相結(jié)構(gòu)由菱方-四方相共存(x0.18)轉(zhuǎn)變?yōu)閭瘟⒎较?x≥0.18),并且這一過(guò)程伴隨著鐵電-非各態(tài)歷經(jīng)-各態(tài)歷經(jīng)弛豫相的轉(zhuǎn)變,從而在非各態(tài)歷經(jīng)與各態(tài)歷經(jīng)弛豫相共存處(x=0.20-0.22)獲得了大的電致應(yīng)變：7 kV/mm電場(chǎng)下獲得的應(yīng)變?yōu)?.45%。對(duì)于x0.12組成,介溫測(cè)試出現(xiàn)的兩個(gè)具有不同性質(zhì)的介電異常分別與菱方相和四方相到弛豫相的轉(zhuǎn)變有關(guān)。通過(guò)同步輻射X射線衍射研究進(jìn)一步發(fā)現(xiàn),x0.18組成在極化后均出現(xiàn)了明顯的電疇取向。隨溫度升高,x0.12組成中的菱方相首先出現(xiàn)取向程度的減弱,四方相電疇的取向能維持到更高溫度,隨BMT含量增加,四方相電疇的穩(wěn)定性逐漸減弱,在更低的溫度出現(xiàn)取向程度的減弱。見(jiàn)第二章。(2)結(jié)合BMT-PT和BNT兩個(gè)體系的特點(diǎn)構(gòu)建了新的BMT基三元體系BMT-PT-BNT,成功的實(shí)現(xiàn)了對(duì)應(yīng)變性能的有效調(diào)節(jié)。研究發(fā)現(xiàn),在該體系中通過(guò)進(jìn)行不同的組成設(shè)計(jì)均能夠有效調(diào)節(jié)其介電弛豫特性并在各態(tài)歷經(jīng)與非各態(tài)歷經(jīng)弛豫相共存附近獲得大的電致應(yīng)變：7 kV/mm電場(chǎng)下獲得的應(yīng)變?yōu)?.41-0.43%。通過(guò)原位電場(chǎng)作用下同步輻射X射線衍射研究表明,該體系大應(yīng)變的產(chǎn)生與電場(chǎng)誘發(fā)的弛豫-鐵電轉(zhuǎn)變有關(guān)。同時(shí),由于0.45BMT-PT-0.32BNT組成的極性納米微區(qū)和疇壁均能對(duì)電場(chǎng)做出快速響應(yīng),使得其應(yīng)變表現(xiàn)出頻率不敏感特性。此外,通過(guò)對(duì)相界附近具有偽立方相和四方相共存組成的研究表明,決定其壓電及應(yīng)變性能的原因除與兩相共存有關(guān)外,偽立方相和四方相各自的特性及其相對(duì)含量對(duì)電學(xué)性能同樣具有顯著的影響。見(jiàn)第三章。(3)利用Pb(Mg1/3Nb2/3)03(PMN)對(duì)BMT-PT體系進(jìn)行改性,首次在 BMT-PT-PMN體系中獲得了具有較好的組成不敏感的大應(yīng)變(BMT-0.3PT-xPMN體系在0.2x0.5范圍內(nèi)7 kV/mm電場(chǎng)下獲得的應(yīng)變?yōu)椤?.40%)、溫度不敏感的大應(yīng)變(BMT-0.3PT-0.20PMN組成在室溫-160 ℃范圍內(nèi)5 kV/mm電場(chǎng)下獲得的應(yīng)變?yōu)椤?.30%±10%)以及具有較小應(yīng)變滯后的大應(yīng)變(BMT-0.3PT-0.45PMN組成在7 kV/mm電場(chǎng)下獲得的應(yīng)變?yōu)?.42%,應(yīng)變滯后為～23%),使得該體系有望成為一種很有潛力的驅(qū)動(dòng)器用陶瓷材料。利用同步輻射X射線衍射并結(jié)合其它測(cè)試手段,研究了該體系中大應(yīng)變的產(chǎn)生機(jī)理及應(yīng)變性能改善的機(jī)理。研究發(fā)現(xiàn),該體系大應(yīng)變的產(chǎn)生與電場(chǎng)誘發(fā)的弛豫-鐵電轉(zhuǎn)變有關(guān),并且轉(zhuǎn)變過(guò)程中中間相的出現(xiàn)能夠顯著降低應(yīng)變的滯后。應(yīng)變的溫度不敏感特性與富BMT組成特殊的疇結(jié)構(gòu)有關(guān),導(dǎo)致該體系的鐵電-弛豫轉(zhuǎn)變溫度與凍結(jié)溫度之間存在較大的差距,因此能夠在較寬的溫度區(qū)間內(nèi)獲得非各態(tài)歷經(jīng)與各態(tài)歷經(jīng)弛豫相共存。此外,不同電場(chǎng)下相結(jié)構(gòu)隨溫度變化的穩(wěn)定性及應(yīng)變形成機(jī)制的不同對(duì)應(yīng)變溫度穩(wěn)定性也有明顯影響。同時(shí),這一特殊疇結(jié)構(gòu)也使得該體系在較寬的組成區(qū)間內(nèi)能夠出現(xiàn)非各態(tài)歷經(jīng)與各態(tài)歷經(jīng)弛豫相共存,獲得組成不敏感的大應(yīng)變。這一研究為鉍基鈣鈦礦體系應(yīng)變性能的改善提供了一種新的組成設(shè)計(jì)思路。見(jiàn)第四章。(4)利用PMN取代BiFe03,首次在BiFe03-PbTi03-xPMN(BF-PT-xPMN)體系中實(shí)現(xiàn)了低電場(chǎng)誘導(dǎo)產(chǎn)生大的電致應(yīng)變,顯著地提高了這一類材料的動(dòng)態(tài)d33*：x=0.35組成在2.5-7 kV/mm電場(chǎng)區(qū)間內(nèi)應(yīng)變?yōu)椤?.22-0.55%,并且在3.5 kV/mm電場(chǎng)下獲得了最大的動(dòng)態(tài)d33'=～1100 pm/V,對(duì)于材料的實(shí)際應(yīng)用具有重要價(jià)值。同時(shí),在富PMN一側(cè)獲得了具有較小應(yīng)變滯后的大應(yīng)變：x=0.68組成在5 kV/mm電場(chǎng)下獲得的應(yīng)變?yōu)椤?.33%,應(yīng)變滯后為～25%。通過(guò)對(duì)不同組成在升降電場(chǎng)過(guò)程中相結(jié)構(gòu)變化的研究發(fā)現(xiàn),該體系中大應(yīng)變的產(chǎn)生與電場(chǎng)誘發(fā)的弛豫-鐵電轉(zhuǎn)變(極性納米微區(qū)的長(zhǎng)大)、菱方相電疇的翻轉(zhuǎn)以及菱方-四方相變有關(guān)。其中,菱方相電疇翻轉(zhuǎn)對(duì)電致應(yīng)變產(chǎn)生的額外貢獻(xiàn)對(duì)該體系應(yīng)變性能的提高具有重要的作用。見(jiàn)第五章。(5)通過(guò)系統(tǒng)分析不同鉍基鈣鈦礦體系中電致應(yīng)變與結(jié)構(gòu)之間的關(guān)系,對(duì)鉍基鈣鈦礦體系產(chǎn)生大應(yīng)變的機(jī)理及應(yīng)變性能改善的機(jī)理作了進(jìn)一步研究。首先,我們首次明確了電場(chǎng)誘發(fā)的弛豫-鐵電可逆轉(zhuǎn)變過(guò)程的本質(zhì)是材料中極性納米微區(qū)在電場(chǎng)作用下的長(zhǎng)大,以及隨后的電疇翻轉(zhuǎn)及鐵電相變,并對(duì)鉍基鈣鈦礦體系在電場(chǎng)作用下的電疇演變過(guò)程進(jìn)行了總結(jié)。其次,我們揭示了升降電場(chǎng)過(guò)程中相變過(guò)程的不對(duì)稱性是導(dǎo)致鉍基鈣鈦礦弛豫鐵電體系應(yīng)變滯后的主要原因,進(jìn)而通過(guò)組成優(yōu)化設(shè)計(jì)達(dá)到了減小應(yīng)變滯后的目的。通過(guò)微觀結(jié)構(gòu)的分析我們認(rèn)為,在加載電場(chǎng)的周期過(guò)程中相變過(guò)程不對(duì)稱現(xiàn)象的出現(xiàn)與化學(xué)有序區(qū)在電場(chǎng)作用下的運(yùn)動(dòng)以及在鐵電疇疇壁處的富集有關(guān)。見(jiàn)第六章。
[Abstract]:With the discovery of large electrostrain phenomena in the (Na0.5Bi0.5) TiO3 (BNT) system and other bismuth perovskite systems, the study of the strain properties of the bismuth perovskite system has gradually become a research hotspot in recent years. However, there are many problems in the study of the bismuth perovskite system: for example, the existing research is mainly aimed at BNT-BaTiO3/ (K0.5 Bi0.5) the TiO3 (BT/KBT) two element system or the three element system prepared as a matrix, is relatively less studied for other BNT systems or other bismuth based perovskite systems; these systems can only obtain large strains at a higher electric field; the strains obtained in these systems have obvious composition and temperature dependence and larger. The strain generation mechanism of bismuth based perovskite system and the specific process of strain production are not very clear. In this paper, a comparative study of different bismuth based perovskite systems and the corresponding optimization design have been made in this paper, and the strain performance of the bismuth based perovskite system has been greatly improved. The bismuth based perovskite ceramics with excellent strain characteristics were obtained. Based on various testing methods, the relationship between the composition, structure and properties of different systems was deeply studied. The mechanism of large strain production of bismuth perovskite system and the adjustment mechanism of strain properties were further studied. The main contents of the full text are as follows. (1) (1) on the basis of BNT-PbTiO3, using Bi (Mg0.5Ti0.5) O3 to replace BNT, the phase structure and electrical properties of BNT-PbTiO3-xBi (Mg0.5Ti0.5) O3 (BNT-PT-xBMT) three element system are studied. It is found that the phase structure of the system is changed from rhomboid tetragonal phase to pseudo cubic phase (x > 0.18) with the increase of BMT content. The process is accompanied by the transition of the ferroelectric - non state - all States - the relaxation phase of each state, thus the large electroinduced strain is obtained in the non state period of the coexistence of the relaxation phase (x=0.20-0.22) in each state. The strain obtained under the 7 kV/mm electric field is 0.45%. for the x0.12, and the dielectric anomalies of the dielectric temperature test are different from the diamond, respectively. The square phase and the Quartet phase are related to the transition of the relaxation phase. Through the study of synchrotron radiation X ray diffraction, it is found that the x0.18 composition appears obvious domain orientation after polarization. As the temperature rises, the diamond square phase in the x0.12 composition decreases first, and the orientation of the Quartet phase domain can be maintained to a higher temperature, with the increase of the content of the BMT. The stability of the Quartet phase domain gradually weakened and the degree of orientation decreased at a lower temperature. See second chapter. (2) a new BMT based three element system BMT-PT-BNT was constructed in combination with the characteristics of the two systems of BMT-PT and BNT, which successfully realized the effective adjustment of the strain performance. The dielectric relaxation characteristics can be effectively regulated and large electroinduced strain is obtained near the coexistence of the relaxation phase in each state. The strain obtained under the 7 kV/mm electric field is 0.41-0.43%. through the synchronous radiation X ray diffraction study under the action of the in situ electric field, which shows that the large strain of the system and the relaxation ferroelectric transition induced by the electric field At the same time, due to the rapid response of the polar nanoscale and domain walls composed of 0.45BMT-PT-0.32BNT to the electric field, the strain shows a frequency insensitivity. In addition, a study of the coexistence of pseudo cubic and tetragonal phase in the vicinity of the phase boundary shows that the reasons for determining its piezoelectric and strain properties are coexisting with the two phases. In addition, the characteristics and relative content of the pseudbocube and tetragonal phase have a significant influence on the electrical properties. See the third chapter. (3) using Pb (Mg1/3Nb2/3) 03 (PMN) to modify the BMT-PT system, the large strain with a better composition insensitive (BMT-0.3PT-xPMN system in the 0.2x0.5 range) is obtained for the first time in the BMT-PT-PMN system. The strain obtained under the internal 7 kV/mm electric field is 0.40%), the large strain which is insensitive to temperature (the strain obtained by the BMT-0.3PT-0.20PMN in the 5 kV/mm electric field within the range of -160 C at room temperature is 0.30% + 10%) and a large strain with a smaller strain lag (the strain of the BMT-0.3PT-0.45PMN composition under 7 kV/ mm electric field is 0.42%, and the strain lag is 2). 23%) the system is expected to be a promising ceramic material for actuators. Synchrotron radiation X ray diffraction and other testing methods have been used to study the mechanism of large strain production and the mechanism of strain performance improvement in the system. The study shows that the large strain of the system is related to the relaxation ferroelectric transition induced by electric field, The occurrence of the mesophase in the transition process can significantly reduce the lag of the strain. The temperature insensitivity of the strain is related to the special domain structure of the rich BMT, which leads to a large gap between the ferroelectric relaxation transition temperature and the freezing temperature of the system, so it can be obtained in the wider range of temperature range and in the different states and states. In addition, the phase structure under different electric fields has an obvious influence on the stability of the temperature change and the different strain formation mechanism corresponding to the temperature stability. At the same time, this special domain structure can also make the system coexist with each state of the relaxation phase in the wider range of composition, and the composition of the system can be obtained. Sensitive large strain. This study provides a new design idea for the improvement of the strain performance of the bismuth perovskite system. See Chapter fourth. (4) using PMN to replace BiFe03 for the first time in the BiFe03-PbTi03-xPMN (BF-PT-xPMN) system, a low electric field is induced to produce a large electroinduced strain and a significant increase in the dynamic d33* of this kind of material. The composition of x=0.35 should be changed to 0.22-0.55% in the 2.5-7 kV/mm electric field interval, and the maximum dynamic d33'= ~ 1100 pm/V is obtained under the 3.5 kV/mm electric field. It is of great value for the practical application of the material. At the same time, the large strain with a smaller strain lag is obtained on the rich PMN side: the strain obtained by the x=0.68 composition in the 5 kV/mm electric field. For 0.33%, the strain lag is to 25%. through the study of the phase structure change of the different composition in the process of the electric field. It is found that the generation of large strain in the system is related to the relaxation ferroelectric transition (the growth of the polar nanoscale micro area) induced by the electric field, the reversal of the rhombus phase domain and the rhombus tetragonal phase transition. The additional contribution of strain generation plays an important role in improving the strain performance of the system. See fifth chapters. (5) through systematic analysis of the relationship between the electrostrain and structure of different bismuth perovskite systems, the mechanism of producing large strain and improving the strain performance of bismuth based perovskite system are further studied. First, we For the first time, it is clear that the essence of the relaxation ferroelectric reversible transformation process induced by the electric field is the growth of polar nanometers in the material under the action of the electric field, and the subsequent electric domain inversion and ferroelectric phase transition, and the evolution process of the domain of the bismuth perovskite system under the action of the electric field. Secondly, we reveal the phase in the process of the elevating electric field. The asymmetry of the changing process is the main cause of the strain lag in the relaxation ferroelectric system of the bismuth based perovskite, and then the purpose of reducing the strain lag is achieved through the composition optimization design. Through the analysis of the microstructure, we think that the asymmetric phenomenon of the phase transition process and the chemical ordered area are in the electric field during the period of the loading of the electric field. The motion and the enrichment at the domain walls of ferroelectric domains are described in the sixth chapter.
【學(xué)位授予單位】：合肥工業(yè)大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2015
【分類號(hào)】：TQ174.1

【參考文獻(xiàn)】

相關(guān)期刊論文 前1條

1 姚喜,陳至立;弛豫型鐵電體[J];壓電與聲光;1984年06期

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本文編號(hào)：2124405