钛酸铋钠基无铅压电陶瓷的制备与改性研究

发布时间：2018-03-27 20:11

本文选题：钛酸铋钠基陶瓷　切入点：Rietveld精修　出处：《西北工业大学》2015年硕士论文

【摘要】：钛酸铋钠在室温下有良好的铁电性能,它是A位离子复合钙钛矿型铁电体,并有相对较高的居里温度(320°C)和大的剩余极化强度38μC/cm2,是一种具有良好发展前景的无铅压电陶瓷。因此,本文用传统固相烧结方法制备了钛酸铋钠基陶瓷,研究了不同掺杂类型对陶瓷的微观形貌及电学性能的影响,探讨了不同成分的陶瓷样品的介电弛豫特性和相变特性。首先,利用传统固相烧结方法制备出Bi_(0.5)Na0.5Ti1-xMnx O3-δ(BNTM10000x,x=0,0.25%,0.5%,0.75%,1%,1.5%,2%)陶瓷。在室温下利用Rietveld方法对BNT和BNTM25陶瓷的晶体结构进行精修。研究发现少量的氧空位以及显著增加的正方性和晶粒尺寸的变化使得MnO2的掺杂量为x=0.25%时Bi_(0.5)Na0.5Ti1-xMnxO3-δ陶瓷的机电耦合性能以及电学性能都达到最优。过量的掺杂导致了氧空位的富集以及铁电-弛豫相转变并进一步导致了电学性能的恶化。BNTM25陶瓷的剩余极化强度Pr=48.5mC/cm2,机电耦合系数kp=0.18,电滞应变S33=0.24%,压电系数d33=105 pC/N。除此之外,BNTM25陶瓷在室温下经过106次极化后几乎没有显著疲劳,表明该组分无铅压电陶瓷材料具有潜在的应用。其次,为了研究不同掺杂类型对BNT基压电陶瓷的结构及性能的影响,制备了Bi_(0.5)Na0.5MnxTi1-xO3、Bi_(0.5)Na0.5NbxTi1-xO3、Bi_(0.5)Na0.5(Mn0.5Nb0.5)xTi1-xO3和BNT陶瓷。详细研究并分析了Mn受主掺杂、Nb施主掺杂以及二者共掺杂对BNT陶瓷晶体结构及电学性能的影响及原因。通过抑制Ti4+?Ti3+的还原反应以及含高密度局域化电子的缺陷偶极子的形成,MnNb共掺杂的BNT陶瓷显著提高了材料的居里温度以及去极化温度。经极化后相比于BNT陶瓷其剩余极化强度及总应变均有提高。同时,Nb2O5掺杂略微提高了BNT陶瓷的抗疲劳特性,MnCO3施主掺杂将BNT陶瓷的无疲劳极化次数提高到105次,而二者共掺杂的BNT陶瓷在疲劳极化106后无疲劳现象。最后,研究了三元(1-x)Bi_(0.5)(Na0.9K0.1)0.5TiO3 xSrTi0.8Zr0.2O3(SZT1000x,x=0,0.2%,0.4%,0.6%,0.8%,1%)陶瓷。室温下测量的铁电P E回线以及极化电流密度J E曲线充分说明了加压过程中铁电畴以及纳米极性微区(PNRs)的变化。大的应变是因为在外电场为零时材料表现为非极性相,且在外电场下可以轻易地转变成长程铁电相,一旦外电场消失,系统又回复到未极化状态。为了研发出在较低的电场下具有大的应变的陶瓷材料,研究了不同组分和不同外加电场时应变的变化。发现当SZT的掺杂量为0.6%mol时,外加电场为50 kV/cm时应变为0.44%,Smax/Emax达到744 pm/V。值得注意的是,该组分在外加电场仅仅为40 kV/cm时就得到了相对较大的应变,此时Smax/Emax也达到了717pm/V,这意味着该材料有希望应用到压电驱动器上。
[Abstract]:Sodium bismuth titanate has good ferroelectric properties at room temperature. It is a perovskite-type ferroelectric with a relatively high Curie temperature of 320 掳C) and a high residual polarization strength of 38 渭 C / cm ~ 2. It is a kind of lead-free piezoelectric ceramics with good prospects. In this paper, bismuth bismuth titanate based ceramics were prepared by traditional solid-state sintering method. The effects of different doping types on the microstructure and electrical properties of the ceramics were studied. The dielectric relaxation and phase transition characteristics of ceramic samples with different compositions were investigated. The Bi_(0.5)Na0.5Ti1-xMnx O3- 未 BNTM10000xnx 0.25x and 0.750.75 ceramics were prepared by conventional solid-state sintering method. The crystal structures of BNT and BNTM25 ceramics were refined by Rietveld method at room temperature. It was found that a small amount of oxygen vacancies and significant increase in square and grain size changes were observed. When the doping amount of MnO2 is x = 0.25, the electromechanical coupling properties and electrical properties of MnO2 ceramics are optimized. Excessive doping leads to the enrichment of oxygen vacancies and the transition of ferroelectric-relaxation phase and further leads to the evil of electrical properties. The residual polarization strength of BNTM25 ceramics is 48.5mC / cm ~ 2, the electromechanical coupling coefficient is 0.18, the hysteresis strain S _ 33N _ (0.24) is 0.24, and the piezoelectric coefficient is d33 ~ 105pC / N. in addition, the BNTM25 ceramics have almost no fatigue after 106 polarization at room temperature. In order to study the effect of different doping types on the structure and properties of BNT based piezoelectric ceramics. The effects of mn acceptor doping and co-doping on the crystal structure and electrical properties of BNT ceramics have been studied and analyzed in detail, including the preparation of Biaphe, Na0.5NbxTi1-xO3, Na0.5Nb0.5Nb0.5Nb, xTi1-xO3 and BNT ceramics. The effect of mn acceptor doping and co-doping on the crystal structure and electrical properties of BNT ceramics were studied and analyzed in detail. The effects of mn acceptor doping and co-doping on the crystal structure and electrical properties of BNT ceramics were studied and analyzed in detail. The effect of mn acceptor doping and co-doping on the crystal structure and electrical properties of BNT ceramics were investigated. The reduction reaction of Ti3 and the formation of defect dipoles containing high density localized electrons in BNT ceramics doped with Mn-Nb have significantly increased the Curie temperature and depolarization temperature. Compared with BNT ceramics, the remanent polarization is stronger after polarization. At the same time, the fatigue resistance of BNT ceramics was slightly improved by doping NB _ 2O _ 5, and the number of non-fatigue polarization of BNT ceramics was increased to 105 times by doping with MNO _ 3 donor. However, the co-doped BNT ceramics have no fatigue phenomenon after fatigue polarization. Finally, The changes of ferroelectric domains and nano-polar microregions (PNRs) during pressurization are well illustrated by the measurements of the ferroelectric P E loop and the polarization current density J E curves at room temperature. The field shows a nonpolar phase at 00:00. And the external electric field can be easily transformed into a long range ferroelectric phase. Once the external electric field disappears, the system returns to a non-polarized state. In order to develop ceramic materials with large strain at a lower electric field, The strain changes of different components and different applied electric fields are studied. It is found that when the doping amount of SZT is 0.6%mol and the applied electric field is 50 kV/cm, it should be changed to 0.44% Smax / Emax up to 744 pm / V. When the applied electric field is only 40 kV/cm, the strain of the component is relatively large, and the Smax/Emax reaches 717 pm / V, which means that the material can be applied to piezoelectric actuators.
【学位授予单位】：西北工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TM282

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