【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(jī)電耦合系數(shù)以及優(yōu)異的鐵電壓電性能等而備受關(guān)注。另外,發(fā)現(xiàn)該材料還具有潛在的離子電導(dǎo)特性,引發(fā)了新一輪探索。而其作為鐵電壓電材料應(yīng)用時(shí),矯頑場(chǎng)較高極化困難以及漏電流較大,對(duì)其性能仍需進(jìn)一步改善;作為電解質(zhì)應(yīng)用時(shí),材料的電導(dǎo)性能也仍需進(jìn)一步提高。因此,本論文通過離子摻雜及固溶改性手段對(duì)鈦酸鉍鈉材料進(jìn)行改性,以提高不同用途下材料的性能,并對(duì)陶瓷樣品的微結(jié)構(gòu)及電學(xué)性能進(jìn)行了研究。基于離子摻雜改性原理,采用改進(jìn)的固相反應(yīng)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(xué)性能測(cè)試系統(tǒng)等測(cè)試手段,研究了Sr~(2+)、Ga~(3+)共摻雜量對(duì)NBT陶瓷的相結(jié)構(gòu)、微觀形貌、阻抗特性及介電性能的影響規(guī)律,并對(duì)材料的電導(dǎo)率進(jìn)行了計(jì)算分析。結(jié)果表明:引入一定量的Sr~(2+)、Ga~(3+)后,NBT陶瓷的電導(dǎo)性能得到提升,在阻抗圖譜中其晶粒電導(dǎo)與晶界電導(dǎo)能夠明顯區(qū)分,電導(dǎo)機(jī)制從電子電導(dǎo)轉(zhuǎn)變?yōu)殡x子電導(dǎo)。隨著Sr~(2+)、Ga~(3+)摻雜量的增加,材料的總電導(dǎo)率、晶粒電導(dǎo)率及晶界電導(dǎo)率均先增大后減小,當(dāng)x=0.O_3時(shí),總電導(dǎo)率在810℃下高達(dá)0.024S/cm,電導(dǎo)激活能降低至0.48eV,表明該材料在固體電解質(zhì)應(yīng)用方面很有潛在的應(yīng)用價(jià)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(xué)性能的變化規(guī)律。結(jié)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(jié)構(gòu)。La(Zn_(0.5)Ti_(0.5))O_3的引入起到了細(xì)化晶粒的作用,且晶粒棱邊更分明,同時(shí)對(duì)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(qiáng),介電弛豫激活能降低,當(dāng)x=0.018時(shí)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(chǎng)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(chǔ)上,引入0.06BaTiO_3來(lái)構(gòu)建NBT的準(zhǔn)同型相界(MPB)。結(jié)果發(fā)現(xiàn):當(dāng)x=0.0O_3時(shí)在電場(chǎng)的作用下引發(fā)的相變?yōu)椴豢赡嫦嘧?當(dāng)x=0.018時(shí),該相變?yōu)榭赡嫦嘧?且其動(dòng)態(tài)壓電常數(shù)高達(dá)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(jié)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(dǎo)特性。隨著LaGaO_3引入量的增加,材料體系的電導(dǎo)激活能與介電弛豫激活能均有所降低,在x=0.012時(shí),電導(dǎo)激活能為1.30 eV,介電弛豫激活能為0.65 eV,并進(jìn)一步探索比較了電導(dǎo)激活機(jī)制與介電激活機(jī)制,表明該類材料在中溫段的離子傳導(dǎo)主要以隧道傳導(dǎo)機(jī)制進(jìn)行,使其有望作為中溫型固體電解質(zhì)材料應(yīng)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(hào)：2454103