Na0.5Bi0.5TiO3-Ba0.5Sr0.5Nb2O6无铅压电陶瓷的研究

采用固相法制备了(1-x)(Na0.5Bi0.5)TiO3-xBa0.5Sr0.5Nb2O6(0≤x≤1.0％)(简称(1-x)NBT-xBSN)无铅压电陶瓷,研究了不同BSN含量(x=0,0.1％,0.3％,0.5％,0.7％,1.0％,摩尔分数)样品的物相组成、显微结构及电性能.结果表明:所有样品均为纯钙钛矿结构,随掺杂量x的增加,陶瓷的相对密度pr、压电常数d33和机电耦合系数kp均先增大后降低,机械品质因子Qm和退极化温度Td则逐渐下降.该体系陶瓷具有弥散相变特征,弥散指数介于1.6～1.7.当x=0.5％时,陶瓷获得最佳性能:d33=92pC/N,kp=0.164,Qm=89,εr=650,tanδ=5.47％,pr=96.5％.     

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。     

(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。     

Bi_(0.5)K_(0.5)TiO_3掺杂对0.945K_(0.5)Na_(0.5)NbO_3-0.045LiSbO_3无铅压电陶瓷结构性能的影响

采用传统固相合成法合成(1-x)(0.945K0.5Na0.5NbO3-0.045LiSbO3)-x(Bi0.5K0.5TiO3)(简记为(KNN-LS)(1-x)-BKTx))无铅压电陶瓷,研究不同BKT掺入量(x=0.000,0.005,0.010,0.015,0.020,0.025,0.030)对该体系陶瓷的微观结构和压电介电性能。结果表明:x≤0.025时,均可形成单一钙钛矿结构;与KNN-LS相比,体积密度(ρ)、机械耦合系数kp、kt显著提高;d33、介电损耗tanδ、机械品质因数Qm和次级相变温度降低;当x=0.020时,样品的整体性能达到最佳值:ρ=4.239g/cm3,d33=94pC/N,kp=30.9%,kt=20.7%,tanδ=0.024,相对介电常数εT33/ε0=2468,Qm=53.95,次级相变温度降至室温以下,温度稳定性好。     

Sr和Mn复合掺杂(Na0.8K0.2)0.5Bi0.5TiO3无铅压电陶瓷

用固相法制备了(Na0.8K0.2)0.5Bi0.5TiO3+xmol%SrCO3+xmol%MnCO3(0≤x≤1.25%)(简称NKBTSM)无铅压电陶瓷,用XRD、SEM、Agilent 4294A精密阻抗仪等对该体系陶瓷的结构与电性能进行表征。结果表明:所制备的NKBTSM陶瓷样品均为单一的钙钛矿结构。Sr和Mn的复合掺杂促进了晶粒的长大,并提高了致密度。与纯NKBT陶瓷相比,掺杂Sr和Mn能提高陶瓷的压电常数d33、机电耦合系数kp和机械品质因子Qm,降低陶瓷的介质损耗tanδ。该系陶瓷具有介电弛豫特性,弥散因子随x的增加先增大后减小。综合考虑:x=1.00%陶瓷的电学性能最佳:d33=152pC/N,Qm=195,kp=28.66%,εr=701,tanδ=2.84%。     

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。     

W6+掺杂对Na0.5Bi2.5Ta2O9陶瓷的结构与电学性能影响

采用传统固相法制备Na0.5Bi2.5Ta2-xWxO9 (NBTO-x,0≤x≤0.05)无铅压电陶瓷,研究W6+掺杂对NBTO陶瓷结构和电学性能的影响.XRD结果显示,所有陶瓷样品均生成了m=2的铋层状结构化合物,随着掺杂量的增加,样品的正交畸变先减小后增大;W6+掺杂提高了样品的压电与铁电性能,当x=0.03时,...     

(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。     

Co、Mn共掺杂铋层状Na_(0.5)Bi_(4.5)Ti_4O_(15)无铅压电陶瓷的显微结构及电性能

采用固相法制备Na0.5Bi4.5Ti4O15+x%Co2O3+y%MnCO3(NBT-CM-x)(y=0.1x)铋层状无铅压电陶瓷,研究了Co、Mn共掺杂对Na0.5Bi4.5Ti4O15陶瓷显微结构和电性能的影响。结果表明:所有样品均为铋层状结构;Co、Mn共掺杂能促进陶瓷晶粒生长;随Co、Mn共掺杂量的增加,Curie温度TC逐渐升高(均在635℃以上);Cole-Cole图出现2个圆弧,表明存在晶粒和晶界效应;适量Co、Mn共掺杂提高了Na0.5Bi4.5Ti4O15陶瓷的压电常数d33、剩余极化强度Pr、机械品质因数Qm和相对介电常数εr,降低了直流电导率σDC和介电损耗tanδ。当x=3.0时,NBT-CM-x陶瓷的综合性能最佳:d33=24pC/N,Pr=11.70μC/cm2,Qm=3 117,εr=198,tanδ=0.19%,kp=9.9%,kt=14.7%,表明该陶瓷材料具有良好的高温应用前景。     

(1-x)Li0.05(K0.5Na0.5)0.95NbO3-x(Bi0.5Na0.5)TiO3无铅压电陶瓷的结构与电性能研究

采用固相反应法制备了(1-x)Li0.05(K0.5Na0.5)0.95NbO3-x(Bi0.5Na0.5)TiO3(LKNN-BNT)无铅压电陶瓷,研究了BNT的添加量x(0,0.005,0.01,0.02)对LKNN-BNT陶瓷的结构与电性能影响。X射线衍射(XRD)分析结果表明当x≤0.005时,陶瓷为正交钙钛矿结构,而当x≥0.01时,陶瓷则转变为四方钙钛矿结构,说明该陶瓷的多型相转变(PPT)区域为0.005相似文献   

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。     

溶胶-凝胶法合成(Na0.5Bi0.5)TiO3微粉

以钛酸四丁酯、硝酸铋、醋酸钠和冰醋酸为原料,利用溶胶-凝胶工艺得到透明凝胶,经干燥后煅烧成(Na0.5Bi0.5)TiO3微粉。通过对溶胶体系水/醇盐的摩尔比、初始pH值及胶凝温度对(Na0.5Bi0.5)TiO3凝胶体系溶胶-凝胶形成过程影响的研究,发现水/醇盐比R在35≤R≤60,pH在2.2~3.5,反应温度在40~60℃时,能够得到透明的溶胶;通过TG-DTA、SEM、X-ray等分析手段对(Na0.5Bi0.5)TiO3粉体进行测试,表明在650℃合成1h可以得到单一钙钛矿(Na0.5Bi0.5)TiO3晶体;采用TEM对(Na0.5Bi0.5)TiO3干凝胶粉体分析其粒径大小约为10nm。     

Temperature-stable dielectric ceramics based on Na0.5Bi0.5TiO3

Multiple ion substitutions to Na_0.5Bi_0.5TiO₃ give rise to favourable dielectric properties over the technologically important temperature range ?55?°C to 300?°C. A relative permittivity, ε_r,?=?1300?±?15% was recorded, with low loss tangent, tanδ?≤?0.025, for temperatures from 310?°C to 0?°C, tanδ increasing to 0.05 at ?55?°C (1?kHz) in the targeted solid solution (1–x)[0.85Na_0.5Bi_0.5TiO₃–0.15Ba_0.8Ca_0.2Ti_1-yZr_yO₃]–xNaNbO₃: x?=?0.3, y?=?0.2. The ε_r-T plots for NaNbO₃ contents x?<?0.2 exhibited a frequency-dependent inflection below the temperature of a broad dielectric peak. Higher levels of niobate substitution resulted in a single peak with frequency dispersion, typical of a normal relaxor ferroelectric. Experimental trends in properties suggest that the dielectric inflection is the true relaxor dielectric peak and appears as an inflection due to overlap with an independent broad dielectric peak. Process-related cation and oxygen vacancies and their possible contributions to dielectric properties are discussed.     

Microstructure and suppressed thermal depolarisation behaviours of lead-free Na0.5Bi0.5TiO3:ZnO ferroelectric composite ceramics

ABSTRACT

A 0–3 type 0.8Na_0.5Bi_0.5TiO₃(BNT):0.2ZnO lead-free ferroelectric composite ceramic structure was prepared by a solid-state oxide route. The X-ray diffraction analysis and scanning electron microscopy observation indicate that ZnO grains were scattered in the matrix consisting of BNT grains to form a (0–3) type composite structure, and a third phase Zn₂TiO₄ was formed due to the reaction ability of nano-sized ZnO with NBT compositions. The temperature-dependent electrical responses show that the dielectric anomaly at around 200°C inherited from NBT itself was suppressed as ZnO is composited, and the P_r of the specimen sintered at 1000°C keeps almost unchanged as the poling temperature is 175°C, while its retained piezoelectric strain d₃₃ value maintains 77% of the initial as exposed to 125°C annealing. These results suggest that the thermal depolarisation of BNT is suppressed due to the introduction of ZnO, even though the third phase Zn₂TiO₄ exists.     

Effects of BiMO3 on dielectric,ferroelectric, and piezoelectric properties of perovskite lead‐free piezoelectric BaTiO3–(Bi0.5Na0.5)TiO3 ceramics

New lead‐free piezoelectric ceramics of 0.9BaTiO₃–(0.1?x)(Bi_0.5Na_0.5)TiO₃–xBiMO₃, M=Al and Ga, where x=0.00‐0.10, were fabricated by the solid‐state reaction technique. The effect of BiMO₃ contents on the perovskite structure, phase transition, and dielectric, ferroelectric, and piezoelectric properties was investigated. X‐ray diffraction patterns showed that the ceramics exhibit a monophasic perovskite phase up to x=0.06, suggesting stabilized perovskite structures with B‐site aliovalent substitutions. Compositional‐dependent phase transitions were observed from tetragonal to pseudo‐cubic phase with increasing BiMO₃ amounts. Al³⁺ ions were found to stabilize the transition temperature of the ceramics, while significantly decreasing transition temperature, and a change in the dielectric peak were found with an increasing amount of Ga³⁺. Regarding Al³⁺ substitution, the remanent polarization (P_r) values were found to decrease slightly with the Al³⁺ amount. With regard to Ga³⁺ substitution, P_r values decreased with the Ga³⁺ amount up to 0.06 and then increased slightly. The ceramics became softer with a higher degree of substitution according to the lower coercive field (E_c), when compared with 0.9BaTiO₃–0.1(Bi_0.5Na_0.5)TiO₃ ceramics. Ceramics with a lower degree of substitution and tetragonal phase showed butterfly strain loops that correlated with normal ferroelectric behavior.     

A位元素非化学计量Bi0.5(Na,K)0.5TiO3-BiFeO3压电陶瓷

采用传统陶瓷制备方法,制备了A位元素非化学计量无铅压电陶瓷0.79(Bi0.5Na0.5)tTiO3–0.18(Bi0.5K0.5)tTiO3–0.03BitFeO3(t=0.95～1.05)。研究了A位元素非化学计量对该体系陶瓷微观结构、压电性能的影响,同时通过测量不同外加应力下压电应变常数(d33),研究了影响d33和径向机电耦合系数(kp)的不同机理。结果表明:A位元素缺乏较多时,析出第二相。kp随A位元素过量与不足的增加而减少,d33随A位元素过量的增加基本不变,随A位元素不足的增加而减少。采用极化相位角(θmax)衡量陶瓷极化程度,发现kp随θmax增加而增加,d33随θmax增加变化不明显。d33在低于临界应力时基本不变,当应力高于临界应力后,随应力增加而下降。压电陶瓷中的应力场对畴壁运动与弹性偶极子的作用是影响d33的作用机理之一。     

温度对溶胶-凝胶法制备Bi_(0.5)Na_(0.5)TiO_3粉体X射线衍射特征的影响

作为一种主要的无铅压电陶瓷材料,Bi_(0.5)Na_(0.5)TiO_3(BNT)是一种优良的候选材料.以钛酸四丁酯、五水硝酸铋和无水乙酸钠为原料,用溶胶-凝胶法制备出清澈透明的BNT凝胶;BNT干凝胶经煅烧可得到BNT细粉.XRD谱线表明,其中主要含有杂相Bi_(12)TiO_(20).随着温度的升高,杂相的强度逐渐降低;同时,由于温度的升高,BNT粉体的晶粒增大.XRD指标化后的结果表明,BNT粉体的(101)晶面的原子排列的有序度较好.