【摘要】：鈦酸鉍鈉Na_(0.5)Bi_(0.5)TiO_3(NBT)因其具有較高的居里溫度、良好的機電耦合系數(shù)以及優(yōu)異的鐵電壓電性能等而備受關注。另外,發(fā)現(xiàn)該材料還具有潛在的離子電導特性,引發(fā)了新一輪探索。而其作為鐵電壓電材料應用時,矯頑場較高極化困難以及漏電流較大,對其性能仍需進一步改善;作為電解質應用時,材料的電導性能也仍需進一步提高。因此,本論文通過離子摻雜及固溶改性手段對鈦酸鉍鈉材料進行改性,以提高不同用途下材料的性能,并對陶瓷樣品的微結構及電學性能進行了研究�；陔x子摻雜改性原理,采用改進的固相反應工藝制備了 Na_(0.5)Bi_(0.5-x)Sr_xTi_(1-x)Ga_xO_(3-δ)陶瓷,利用X射線衍射儀、掃描電子顯微鏡及電學性能測試系統(tǒng)等測試手段,研究了Sr~(2+)、Ga~(3+)共摻雜量對NBT陶瓷的相結構、微觀形貌、阻抗特性及介電性能的影響規(guī)律,并對材料的電導率進行了計算分析。結果表明:引入一定量的Sr~(2+)、Ga~(3+)后,NBT陶瓷的電導性能得到提升,在阻抗圖譜中其晶粒電導與晶界電導能夠明顯區(qū)分,電導機制從電子電導轉變?yōu)殡x子電導。隨著Sr~(2+)、Ga~(3+)摻雜量的增加,材料的總電導率、晶粒電導率及晶界電導率均先增大后減小,當x=0.O_3時,總電導率在810℃下高達0.024S/cm,電導激活能降低至0.48eV,表明該材料在固體電解質應用方面很有潛在的應用價值�；诠倘芨男苑椒ǔ晒χ苽淞�(1-x)Na_(0.5)Bi_(0.5)TiO_(3-x)La(Zn_(0.5)Ti_(0.5))O_3系列陶瓷,研究了該系陶瓷的相組成、微觀形貌及電學性能的變化規(guī)律。結果表明:引入一定量的La(Zn_(0.5)Ti_(0.5))O_3后,NBT仍保持單一的鈣欽礦結構。La(Zn_(0.5)Ti_(0.5))O_3的引入起到了細化晶粒的作用,且晶粒棱邊更分明,同時對材料體系的介電性能有顯著影響。隨著La(Zn_(0.5)Ti_(0.5))O_3引入量的增加,材料體系的介電彌散因子增大,弛豫增強,介電弛豫激活能降低,當x=0.018時降至最低,為1.32eV。另外,La(Zn_(0.5)Ti_(0.5))O_3的引入也使得材料體系的鐵電性能得到改善,隨著La(Zn_(0.5)Ti_(0.5))O_3含量的增加,材料體系的矯頑場由43.4 kV/cm降低至23.7kV/cm。為了提高NBT基材料的鐵電性能,在x=0.0O_3和x=0.018組分的基礎上,引入0.06BaTiO_3來構建NBT的準同型相界(MPB)。結果發(fā)現(xiàn):當x=0.0O_3時在電場的作用下引發(fā)的相變?yōu)椴豢赡嫦嘧?當x=0.018時,該相變?yōu)榭赡嫦嘧?且其動態(tài)壓電常數(shù)高達60pm/V。將LaGaO_3組分引入到鈦酸鉍鈉體系中成功制備了(1-x)Na_(0.5)Bi_(0.5)TiO_(3-x)LaGaO_3系列陶瓷,結果發(fā)現(xiàn):引入微量的LaGaO_3后NBT以R3c相存在,并且在引入LaGaO_3后并未觀察到NBT材料的離子電導特性。隨著LaGaO_3引入量的增加,材料體系的電導激活能與介電弛豫激活能均有所降低,在x=0.012時,電導激活能為1.30 eV,介電弛豫激活能為0.65 eV,并進一步探索比較了電導激活機制與介電激活機制,表明該類材料在中溫段的離子傳導主要以隧道傳導機制進行,使其有望作為中溫型固體電解質材料應用。
[Abstract]:Sodium bismuth titanate Na_ (0.5) Bi_ (0.5) TiO_3 (NBT) has attracted much attention due to its high Curie temperature, good electromechanical coupling coefficient and excellent ferroelectric properties. In addition, it is found that the material also has the potential ionic conductivity characteristics, leading to a new round of exploration. When it is used as a ferroelectric material, the coercivity field is difficult to be polarized and the leakage current is larger, so the properties of the material still need to be further improved, and as an electrolyte, the conductivity of the material needs to be further improved. Therefore, sodium bismuth titanate was modified by ion doping and solid solution modification in order to improve the properties of the materials in different applications, and the microstructure and electrical properties of ceramic samples were studied. Based on the principle of ion doping modification, Na_ (0.5) Bi_ (0.5) Sr_xTi_ (1) Ga_xO_ (3-未) ceramics were prepared by an improved solid-state reaction process, and X-ray diffractometer was used. The effects of co-doping of Sr~ (2) and Ga~ (3) on the phase structure, microstructure, impedance and dielectric properties of NBT ceramics were studied by scanning electron microscopy (SEM) and electrical properties testing system. The conductivity of the material was calculated and analyzed. The results show that the conductivity of NBT ceramics is improved by introducing a certain amount of Sr~ (2) and Ga~ (3). In the impedance spectrum, the grain conductance and grain boundary conductance can be distinguished obviously, and the conductivity mechanism changes from electronic conductivity to ionic conductivity. With the increase of doping amount of Sr~ (2) and Ga~ (3), the total conductivity, grain conductivity and grain boundary conductivity of the materials increased first and then decreased, and the total conductivity reached 0.024 S / cm at 810 鈩，

本文編號：2454103