(1-x)Na0.5 Bi0.5 TiO3-xNaNbO3系无铅压电陶瓷的机电性能

采用传统陶瓷的制备方法,制备了(1-x)Na0.5Bi0.5TiO3-xNaNbO3(r=0～0．08)压电陶瓷。X射线衍射分析表明：所研究的组成均能够形成纯钙钛矿(ABOx)型固溶体。不同频率下陶瓷材料的介电常数-温度曲线显示该体系材料具有典型的弛豫铁电体特征,且随着x的增加,其弛豫性特征愈明显。室温下陶瓷材料的饱和电滞回线表明：所研究组成均为铁电体．材料的剩余极化强度P1在x=0．02时具有最大值。检测了不同组成陶瓷的雎电性能,发现材料的压电常数d33和平面机电耦合系数Kp随着x值的增加先增加后降低,在x=0．02时．陶瓷的d33=88pC／N,Kp=0．1792,为所研究组成中的最大值．材料的介电常数εI3/ε0和介电损耗tanδ则随x值的增加而增加。     

Na0.5Bi0.5TiO3-K0.5Bi0.5TiO3系无铅压电陶瓷的极化工艺研究

主要研究了极化电场,极化时间和极化温度等工艺参数对Na0.5Bi0.5TiO3-K0.5Bi0.5TiO3系无铅压电陶瓷介电和压电性能的影响。结果表明:极化电场和极化温度对压电陶瓷的介电、压电性能影响较大,而极化时间则影响较小。适宜的极化电场是3～3.5kV/mm,极化温度70～80℃,极化时间为10～15min。     

Na0.5Bi0.5TiO3-K0.5Bi0.5TiO3系无铅压电陶瓷的制备工艺研究

利用XRD、SEM等分析技术 ,研究了Na0 .5Bi0 .5TiO3 -K0 .5Bi0 .5TiO3 系无铅压电陶瓷的合成温度 ,烧成工艺条件对陶瓷晶体结构、压电性能的影响。结果表明 ,合成温度提高有利于主晶相的形成 ,适当延长保温时间有利于材料的压电性能。该体系随着KBT含量的增加 ,烧结温度提高 ,烧结温度范围变窄。同时研究了极化工艺条件对材料压电性能的影响表明 ,提高极化电场和适当提高极化温度有利于压电性能的提高 ,但过高的温度由于受到材料高温下退极化的影响而导致材料压电性能变差     

Y_2O_3,Fe_2O_3掺杂(Na_(0.5)Bi_(0.5))TiO_3无铅压电陶瓷的研究

采用固相法制备了(Na0.5Bi0.5)TiO3+xmol%Y2O3+xmol%Fe2O3(0≤x≤1.25)(简称NBTYF)无铅压电陶瓷。XRD衍射结果表明,所有陶瓷样品均为单一的钙钛矿结构。SEM表明,掺杂后陶瓷的晶粒尺寸增大。介电温谱表明该体系陶瓷具有弛豫特性,随掺杂量的增加,退极化温度Td向低温方向移动,而居里温度Tc向高温方向移动。陶瓷的密度和压电常数d33和随x的增加先增大后减小,而机械品质因子Qm一直下降。当x=1.00时,该体系陶瓷具有最佳压电性能,d33=106pC/N,Qm=93,kp=16.08%,εr=594,tanδ=5.33%,ρ=5.699g/cm3。     

(K0.5Na0.5)(TaxNb1-x)O3无铅压电陶瓷的性能特征

采用传统电子陶瓷制备工艺制备了(K0.5Na0.5)(TaxNb1-x)O3无铅压电陶瓷。研究了不同Ta含量下(K0.5Na0.5)(TaxNb1-x)O3陶瓷的晶相组成及性能特征。结果表明,(K0.5Na0.5)(TaxNb1-x)O3陶瓷在低Ta含量时形成单一斜方相固溶体,但Ta含量达到0.08mol后则有K6Ta10.8O30次晶相产生。随着Ta的加入,陶瓷的体积密度逐渐增大,居里温度(Tc)逐渐降低。当Ta含量为0.08mol时陶瓷具有良好的铁电、压电性能和介电稳定性能,其压电常数d33为76pC/N。     

Bi0.5Na0.5TiO3基无铅压电陶瓷设计与制备研究的新进展

综述了Bi0.5Na0.5TiO3(BNW)基无铅压电陶瓷体系研究的最新进展,介绍了BNT基无铅压电陶瓷的设计方法及其制备技术.用自洽场离散变分法(self-consult charge-discrete variation-Xa,SCC-DV-Xa)等计算方法可为设计新型BNT基陶瓷提供重要的理论指导.用湿化学法,包括:溶胶-凝胶法、柠檬酸盐法、水热法等,可以合成BNT基纳米粉体,该类方法制备的BNT基粉体具有良好烧结活性,利于致密化烧结,使材料电性能得到改善.用模板晶粒生长技术可获得晶粒生长定向程度很高的BNT基压电陶瓷材料,进而提高材料在特定方向的压电性能.     

Na0.5Bi0.5TiO3基无铅压电陶瓷研究与应用的新进展

综述了钙钛矿结构的Na0.5Bi0.5TiO3(简称BNT)基无铅压电陶瓷的研究现状,并与其它无铅基压电陶瓷进行了对比.列举了近年来BNT 基压电陶瓷的新发展和热门体系,结合笔者承担的相关研究工作内容,总结和指出了BNT基无铅压电陶瓷新的研究思路和相关方向.     

(Na1-xKx)0.5Bi0.5TiO3系的离子挥发性研究

利用固相法制备了(Na1-xKx)0.5Bi0.5TiO3系压电陶瓷,研究其中Bi3 、Na 、K 离子的挥发对其性能的影响。研究结果表明Bi3 的挥发性对样品的性能影响较大,而Na 、K 离子相对较小。     

CeO2、Sb2O3掺杂(Na0.88K0.12)0.5Bi0.5TiO3无铅陶瓷的压电性能研究

采用传统陶瓷的制备方法制备了CeO2(0～1.0wt%)和Sb2O3(0～0.6wt%)掺杂的(Na0.88K0.12)0.5Bi0.5TiO3无铅压电陶瓷。运用XRD技术研究了样品的晶体结构,测试并分析了样品的介电、压电性能以及谐振频率温度系数。结果表明:所有组成均呈三方结构的钙钛矿型固溶体特征。在适当掺杂剂用量范围内,压电陶瓷的压电常数、介电常数和介电损耗升高,而平面机电耦合系数降低。CeO2和Sb2O3掺杂均改善了(Na0.88K0.12)0.5Bi0.5TiO3压电陶瓷频率温度稳定性。     

K_(0.5)Na_(0.5)NbO_3-La_2O_3无铅压电陶瓷性能的研究

采用传统周相反应法制备了K0.5Na0.5NbO3-xmol%La2O3(简称KNN-xLa)系列无铅压电陶瓷,研究了不同La2O3含量(x=0.0,0.05,0.15,0.25,0.35,0.5,1.0)样品的物相组成、显微结构、压电及介电性能.实验结果表明:La2O3的加入并没有改变陶瓷的相结构,体系仍为单一正交相钙钛矿结构.随着掺杂量x的增大样品的压电系数(d33)、机械品质因子(Qm)、平面机电耦合系数(kp)和样品密度(P)都呈现先增大后减少的变化趋势,而介质损耗(tan δ)呈现先变小后增大的变化趋势,烧成温度则随着x的增大而升高.当x=0.15时,材料的综合性能达到最佳,其中P=4.52 g/cm3,d33=120pC/N,Qm=130,kp=0.41,tan δ=0.021.此外,随着x的增大,居里温度Tc则呈现出先升高后降低的趋势,而正交相向四方相的转变温度To-t与Tc变化相反,且当x=0.15时,To-t=189℃,Tc=404℃.     

Y2O3掺杂对(Bi0.5Na0.5)0.94Ba0.06TiO3无铅压电陶瓷性能的影响研究

采用传统固相反应法制备了Y2O3掺杂(Bi0.5Na0.5)0.94Ba0.06TiO3(简写为BNBT6)陶瓷[简称为BNBT6-x(wt%)Y2O3陶瓷].研究了Y2O3 (0.2wt%～0.8wt%)掺杂对BNBT6陶瓷的结构、介电、压电、铁电性能的影响.结果表明,所有Y2O3掺杂陶瓷样品均形成了单一的钙钛矿结构;陶瓷的介电、压电、铁电性能受Y2O3掺杂的影响较为显著:当掺杂0.4wt%Y2O3时,10 kHz频率下测得的室温εr达到1530,且tanδ较小,为0.050,d33达到152 pC/N,kp=0.27,Qm=134.掺杂0.2wt%的Y2O3时BNBT6陶瓷的d33为145 pC/N,kp增大到0.29,Qm达到173,tanδ为0.053;掺杂适量Y2O3的BNBT6陶瓷铁电性能也得到改善.     

Bi0.5Na0.5TiO3基无铅压电陶瓷的研究进展

随着经济的发展和人们环保意识的增强,无铅压电陶瓷的研究和开发越来越引起人们的重视.由于钛酸铋钠(Bi0.5Na0.5TiO3,简称为BNT)基无铅压电陶瓷具有良好的铁电性和高的剩余极化引起了广大学者的关注.本文分析了BNT基无铅压电陶瓷的研究进展,其中晶粒取向生长技术是提高其压电性能的一个重要途径.本文还介绍了一种溶剂热法制备织构化BNT基无铅压电陶瓷的方法.     

High-temperature dielectric and energy storage properties of Bi0.5Na0.5TiO3-based ceramics modified by Sr0.8Na0.4Nb2O6

Sr_0.8Na_0.4Nb₂O₆ with a tungsten bronze structure is introduced into perovskite-structured 0.94(Bi_0.5Na_0.5)TiO₃-0.06BaTiO₃ composition (abbreviated as BNT-BT-xSNN, x = 0-0.04). The temperature stability of dielectric properties and energy storage performance is found to be effectively enhanced by Sr_0.8Na_0.4Nb₂O₆ dopant. When x is 0.03, the temperature ranges covering |ε'-ε'_150°C|/ε'_150°C ≤15% and tanδ ≤ 0.02 are 43°C-404°C and 90°C-422°C, respectively. More importantly, ε′ can be retained as high as 3304 at 150°C. Besides, the variances of energy storage density and its efficiency are 6.4% and 5.3%, respectively, in the temperature range from room temperature (RT) to 180°C. Therefore, this work provides a new method of compositional modification in BNT-based materials to improve their temperature stability of dielectric and energy storage properties.     

(Na1/2Bi1/2)TiO3系无铅压电陶瓷材料研究进展

概述了近年来国内外(Na1/2Bi1/2)TiO3(BNT)基无铅压电陶瓷的研究近况。主要介绍BNT陶瓷及BNT基陶瓷的研究工作。通过非化学计量掺杂及A位空位的存在，使BNT基陶瓷的电性能得到了较大的提高。     

K0.5Na0.5NbO3-BaCu0.5W0.5O3无铅压电陶瓷的结构与性能

以传统固相法工艺制备(1-x)K0.5Na0.5NbO3-xBaCu0.5W0.5O3[(1-x)KNN-xBCW]无铅压电陶瓷,研究不同BCW掺量(x=0％,0.1％,0.25％,0.5％,1.0％,摩尔分数,下同)对KNN陶瓷的晶体结构和电性能的影响,结果表明:x＜0.5％时,KNN陶瓷的相结构没有改变,仍为正交相...     

Preparation of single crystalline Sr0.5Ba0.5Nb2O6 particles

Single crystalline and agglomerate-free ceramic particles are important for fabrication of grain-oriented ceramics by the self-assemble processes. In the present work, preparation of single crystalline Sr_0.5Ba_0.5Nb₂O₆ particles was first explored by traditional solid-state reaction and molten-salt synthesis methods. The results show that the particles synthesized by solid-state reaction were spherical, hard-aggregated and polycrystalline. Molten salt synthesis provides sub-micrometer anisotropic single crystalline Sr_0.5Ba_0.5Nb₂O₆ particles and the morphology of a particle may be adjusted by changing synthesis conditions. The synthesized particles have uniform size distribution and are easily dispersed, thus may suit self-assemble processes to prepare grain-oriented ceramics. Furthermore, effects of synthesis conditions in molten salt synthesis, on the phase formation, morphology and size distribution of SBN particles were investigated.     

Piezoelectric K0.5Na0.5NbO3 Ceramics Textured Using Needlelike K0.5Na0.5NbO3 Templates

Improved performance by texturing has become attractive in the field of lead‐free ferroelectrics, but the effect depends heavily on the degree of texture, type of preferred orientation, and whether the material is a rotator or extender ferroelectric. Here, we report on successful texturing of K_0.5Na_0.5NbO₃ (KNN) ceramics by alignment of needlelike KNN templates in a matrix of KNN powder using tape casting. Homotemplated grain growth of the needles was confirmed during sintering, resulting in a high degree of texture parallel to the tape casting direction (TCD) and the aligned needles. The texture significantly improved the piezoelectric response parallel to the tape cast direction, corresponding to the direction of the strongest <001>_pc orientation, while the response normal to the tape cast plane was lower than for a nontextured KNN. In situ X‐ray diffraction during electric field application revealed that non‐180° domain reorientation was enhanced by an order of magnitude in the TCD, compared to the direction normal to the tape cast plane and in the nontextured ceramic. The effect of texture in KNN is discussed with respect to possible rotator ferroelectric properties of KNN.     

Fabrication of Sr0.5Ba0.5Nb2O6 Nanocrystallite‐Precipitated Transparent Phosphate Glass‐Ceramics

Transparent (Sr_0.5Ba_0.5)Nb₂O₆ (SBN50) nanocrystallite‐precipitated phosphate glass‐ceramics were prepared by a conventional glass‐ceramic process. x(SrO–BaO–2Nb₂O₅) ? (100–4x)P₂O₅ (xSBNP) glasses with a refractive index of 1.9–2.0 exhibited high water resistance owing to the presence of Q⁰ and Q¹ phosphate units. Both bulk and surface crystallization of the SBN50 phase were observed in 20SBNP and 21SBNP glass‐ceramics. Although the nominal content of SBN50 crystals in the 21SBNP glass was larger than that in the 20SBNP glass, the latter exhibited better crystallinity of SBN50 and a higher number density of precipitated SBN nanocrystallites. By tuning the two‐step heat‐treatment and the chemical composition, transparent SBN50‐precipitated glass‐ceramics were successfully obtained. Given that no remarkable increase of the relative dielectric constants was observed after crystallization of the SBN50 nanocrystallites, it is postulated that the relative dielectric constant of the bulk is mainly governed by the amorphous phosphate region, and that the contribution of precipitation of the SBN50 nanocrystallites to the dielectric constant is not very significant in this system.