溶胶–凝胶法制备(Na0.50+xK0.50-2xLix)Nb0.9Ta0.1O3无铅压电陶瓷及其性能

采用溶胶–凝胶法制备Li+取代(K0.5Na0.5)+及Ta5+取代Nb5+的(K0.5Na0.5)NbO3陶瓷粉体,采用无压烧结工艺制备(Na0.50+xK0.50–2xLix)Nb0.9Ta0.1O3(x=0,0.02,0.04)陶瓷样品。研究了前驱体煅烧温度对陶瓷粉体物相组成的影响。分析了不同Li+掺杂量对样品物相组成、微观结构、体积密度及电学性能的影响。结果表明:前驱体的最佳煅烧温度为600℃,通过透射电子显微镜分析陶瓷粉体的粒径为49 nm;不同Li+掺杂量制备的(Na0.50+xK0.50–2xLix)Nb0.9Ta0.1O3陶瓷样品均为正交相钙钛矿结构;随着Li+掺杂量的增加,(Na0.50+xK0.50–2xLix)Nb0.9Ta0.1O3陶瓷的体积密度先增大后减小,介电常数逐渐升高,压电常数先降低再升高,剩余极化强度逐渐升高。Li+掺杂量x为0.04时样品的压电常数(d33=94 pC/N)、相对介电常数(εr=684.33)及剩余极化强度(Pr=98.27μC/cm2)较好。     

W、Zr共同掺杂对铌酸钾钠基无铅压电陶瓷的影响

采用传统固相烧结法制备了0.94(Na0.535K0.48)Nb1–x(W0.5Zr0.5)xO3–0.06Li Sb O3(x=0,0.01,0.02,0.03,0.04)无铅压电陶瓷,其中,钨和锆以摩尔比为0.5:0.5组成掺杂共同体取代Nb,改变(W0.5Zr0.5)掺杂量x,观察钙钛矿结构B位异价元素的掺杂对铌酸钾钠基无铅压电陶瓷的影响。结果表明:陶瓷的晶体结构随着x的增加由四方相转变为正交相,晶格间距减小。掺杂量x=1%时,陶瓷的综合性能良好,压电常数为203 p C/N,机电耦合系数为0.309,相对介电常数为813,Curie温度为350℃,烧结性能也得到了提高。     

（1-x）Bi4Ti3O12–xK0.5Na0.5NbO3铋层状陶瓷的结构与性能

采用固相法制备（1–x）Bi4Ti3O12–xK0.5Na0.5NbO3（BIT–KNN,x=0,0.05,0.10,0.15,0.20,0.30）铋层状压电陶瓷。用X射线衍射分析及扫描电镜等测试方法研究KNN掺量与BIT–KNN陶瓷晶体结构和电性能的关系。结果表明：所有陶瓷样品均为单一的正交相结构;随着KNN掺量的增...     

K0.48Li0.02Na0.5(Nb1–xSbx)O3压电陶瓷的制备与性能EI北大核心CSCD

采用微波烧结法制备了锑掺杂改性K0.48Li0.02Na0.5NbO3(KLNN)压电陶瓷,研究了锑掺杂量(x=0,0.02,0.04,0.06,0.08)对陶瓷的微观结构、表面形貌、介电性能、压电性能和铁电性能的影响。结果表明:在掺杂范围内,各组分的陶瓷样品均形成了单一的钙钛矿结构,结晶良好,晶粒均匀,说明金属锑在KLNN晶格中可以形成均匀固溶体,改善了KLNN基无铅压电陶瓷的微观结构,提高了其压电性能和铁电性能。在x=0.06时,K0.48Li0.02Na0.5(Nb0.94Sb0.06)O3陶瓷样品的Curie温度介电常数峰(εr)、单向电致应变(ε)、压电系数(d33)均达到最大值,分别为εr=5557,ε=0.08%,d33=208 pC/N。     

高介电陶瓷Ag0.9A0.1(Nb0.8Ta0.2)O3(A=Li,Na,K)的研究

采用传统的固相合成法制备了Ag（Nb0.8Ta0.2）O3（ANT）和Ag0.9A0.1（Nb0.8Ta0.2）O3（A=Li,Na,K）样品,并通过X射线衍射,扫描电镜和Raman光谱等手段对样品进行了表征。研究了Li^＋,Na^＋,K^＋取代Ag（Nb0.8Ta0.2）O3中的少量Ag^＋（摩尔比10％）对其介电性能的影响。结果表明：由于Li^＋,K^＋与Ag^＋半径差较大,它们的取代样品中出现了钙钛矿相以外的杂相峰,与未取代样品（ANT）相比介电常数（ε）和介电损耗（tgδ）变大;Na^＋取代样品的X射线衍射谱中只呈现单一的钙钛矿相特征峰．其ε,tgδ较未经取代样品（ANT）的值略有减小。     

BaCu0.5W0.5O3掺杂改性Li0.04Na0.52K0.44Nb0.86Ta0.140Sb0.04O3无铅压电陶瓷

以传统固相法制备了(1-x)Li0.04Na0.52K0.44Nb0.86Ta0.10Sb0.04O3-xBaCu0.5O3[简称(1-x)LF4-xBCW]无铅压电陶瓷,研究了不同BCW掺杂量(x=0%,0.1%,O.2%,O.5%,1%,摩尔分数)对LF4陶瓷的显微结构和电性能的影响.结果表明:引入BCW后,材料仍为钙钛矿结构,当x≥1%时,样品由四方相向正交相转变,出现To-t,Tc则随BCW掺入量的增加向低温区移动.BCW掺杂量对LF4的电性能起到"硬性"掺杂作用,其压电常数d33,平面机电耦合系数kp,介电损耗tan δ和介电常数εr均随着BCW含量的增加而降低,而机械品质因素Qm整体提高.此外,BCW的掺入降低了陶瓷的烧结温度并提高了其密度.     

烧结温度对PCrNi-4压电陶瓷性能的影响

采用传统固相烧结法制备Pb0.94Sr0.06（Zr0.53Ti0.47）O3＋（Ni2O3＋Cr2O3）0.1wt%＋x wt%CeO2（简称PCrNi-4）压电陶瓷,其中x取值为0,0.1,0.3和0.5,研究了烧结温度对陶瓷样品的相结构、显微结构、压电及介电性能。结果标明：所有样品相结构均为三方相与四方向共存。当烧结温度为1280℃,CeO2掺杂量为0.3 wt%时,陶瓷的晶粒大小均匀,致密性良好,具有良好的压电及介电性能（d33=375 pC/N,Kp=0.70115,εT33=1400,tgδ=0.00238）。     

Mn掺杂对铌钽酸盐无铅压电陶瓷性能的影响

采用传统固相反应法制备了Mn掺杂的(K,Na,Li)(Nb,Ta)O3无铅压电陶瓷,研究其介电和压电性能.实验结果表明,MnCO3的加入使样品的烧结温度降低,提高了陶瓷的致密性和压电性能.当MnCO3的添加质量分数为0.2 %的时候,样品的性能达到最佳.     

Ta_2O_5掺杂Bi_2O_3–ZnO–Nb_2O_5陶瓷的晶体结构、结晶化学及介电性能

采用固相反应法制备Bi1.5ZnNb1.5–xTaxO7陶瓷,研究了不同掺杂量Ta2O5对Bi2O3–ZnO–Nb2O5陶瓷相结构、晶体化学特性和介电性能的影响。结果表明:当x≤0.1时,样品均保持单一的立方焦绿石结构(α–BZN)。通过对样品结晶化学计算发现,随着Ta2O5掺杂量的增加,晶格常数a逐渐减小,结晶化学参数键价和AV(O')[A4]增大,AV(O)[A2B2]减小,48f(O)坐标ξ增加。在组成样品晶体结构的多面体中,由6个48f(O)组成的八面体结构(BO6)逐渐变得扭曲,而6个48f(O)和2个8b(O')组成的六面体结构逐渐变得规则,向正立方体结构变化。室温下样品的介电常数和损耗随Ta2O5掺杂量的增加而减小,弛豫度逐渐减小。     

Sb3+掺杂Li0.02(Na0.53K0.48)0.98Nb0.8Ta0.2O3无铅压电陶瓷的电学性能

用传统的固相反应烧结法制备了Li0.02(Na0.53K0.48)0.98 Nb0.8Ta0.2O3-xSb2O3(LNKNT-xSb2O3)无铅压电陶瓷,研究了Sb3+掺杂对陶瓷晶体结构、显微结构及压电性能的影响.研究结果表明,Sb3+掺杂LNKNT陶瓷属于明显的“软性”掺杂,少量掺杂Sb3+能显著提高陶瓷的烧结及压电性能.当烧结温度为1100℃,掺杂量为2wt％时,LNKNT-0.02Sb陶瓷达到最好的压电性能:d33=193 pC/N,KP=49.5％,εr=779,Pr=16μC/cm2,应变达到2.3％,但机械品质因数QM从110.97降低到了85,介电损耗tanδ从1.66％增加到了2.01％.     

Dielectric behavior of Nb2O5-doped TiO2/epoxy thick films

TiO₂/epoxy composite thick films containing the TiO₂ powders doped with 4 and 10 vol% Nb₂O₅ heat treated under vacuum at 1050 and 1150 °C, were prepared by the screen printing and curing steps. The Nb₂O₅-doped TiO₂ ceramic bulks demonstrated a higher effective dielectric constant at different densification environments, as compared with pure TiO₂. The dielectric properties of the TiO₂/epoxy thick films were improved if the heat-treated 4 vol% Nb₂O₅-doped TiO₂ powder was incorporated instead of the un-doped and heat-treated 10 vol% Nb₂O₅-doped TiO₂ powders. The disadvantage of the doped TiO₂ having higher dielectric loss tangent could be minimized after its powder was properly treated and mixed with epoxy to form the TiO₂/epoxy composite. A best result with the dielectric constant of 23 and the loss tangent of 0.046 was obtained for the 40 vol% TiO₂/epoxy composite thick films, where the TiO₂ powder was doped with 4 vol% Nb₂O₅ followed by calcination at 1000 °C in air and heat treatment at 1150 °C under vacuum.     

Conductivity of Na5+xYAlxSi4-xO12 ceramics

A series of ceramics samples, Na_5+xYAl_xSi_4-xO₁₂, has been prepared by a solid state reaction with the starting materials of SiO₂, Y₂O₃, Al₂O₃ and Na₂CO₃. Their crystalline structure and morphology have been studied by the determination of XRD, IR, TG, DTA and SEM. Their conductivity has been measured by means of the complex impedance method. The dependence of the conductivity and density of the samples on the amount of the added Al₂O₃ and the reaction between the conductivity and the temperature have been discussed. When x = 0, the density of the sintering sample is 90% T.D., and the conductivity is 1·48 x 10⁻¹ (ωcm)⁻¹ at 300°C; when x = 0·1, the density is up to 97% T.D., and the conductivity up to 1·74 x 10⁻¹ (ω cm)⁻¹ at 300°C.     

An investigation of (Na0.5K0.5)NbO3–CaTiO3 based lead-free ceramics and surface acoustic wave devices

Lead-free (Na_0.5K_0.5)NbO₃ ceramics doped with CaTiO₃ (0–3 mol%) have been prepared by the conventional mixed oxide method in this paper. All of the CaTiO₃ doped (Na_0.5K_0.5)NbO₃ specimens do not deliquesce as exposed to water for a long time. The samples are characterized by X-ray diffraction analysis, Raman scattering spectra, scanning electron microscopy, and atomic force microscopy. The dielectric, piezoelectric and ferroelectric properties are also investigated. The results show that the addition of CaTiO₃ is very effective in preventing the deliquescence and in improving the electric properties of (Na_0.5K_0.5)NbO₃ ceramics. Finally, surface acoustic wave devices based on lead-free ceramics have been successfully fabricated and their characterization is presented.     

Sintering and dielectric properties of Cu2Ta4O12 ceramics

In this work, Cu₂Ta₄O₁₂ ceramic was investigated as a promising, lead-free, nonferroelectric material with high dielectric permittivity. The results of impedance spectroscopy studies carried out at frequencies 10 Hz to 2 MHz over a wide temperature range from −55 to 700 °C were analyzed in the impedance, dielectric permittivity and electric modulus formalisms. In complex impedance plots two distinct arcs were distinguished, ascribed to the semiconducting grains and to the insulating grain boundaries. Cu₂Ta₄O₁₂ ceramic was found to exhibit a high dielectric permittivity exceeding 10,000 at low frequencies in the temperature range 150–740 °C. High permittivity of this material was attributed to the formation of internal (grain boundary) barrier layer capacitors. The influence of sintering conditions on microstructure, composition and dielectric properties of Cu₂Ta₄O₁₂ ceramics was also studied.     

Temperature-dependent dielectric, impedance and tunability studies on bismuth zinc niobate ((Bi1.5Zn0.5)(Nb1.5Zn0.5)O7) ceramics

Bi₂O₃–ZnO–Nb₂O₅-based pyrochlore ceramics are receiving increasing attention due to their excellent dielectric properties in the microwave frequency range. Site disorder at the pyrochlore A-site is well known for lone pair active cations like Bi³⁺ and is attributed as the reason for this material's high dielectric constant and tunability. Bismuth zinc niobate ((Bi_1.5Zn_0.5)(Nb_1.5Zn_0.5)O₇) [BZN] ceramics are prepared by the conventional solid-state reactions. The relative permittivity (_r) and the dielectric loss tangent (tan δ) of the BZN ceramics sintered at 1000 °C are found to be around 130 and 0.0004, respectively at a frequency of 1 MHz measured at room temperature. The impedance spectroscopy measurements are conducted at different temperatures to separate grain and grain boundary contributions to the dielectric constant. The tunability of these ceramics is studied under a constant dc bias voltage.     

Bi1.5+xZn1.0Nb1.5O7+1.5x（x=0.075,0.15）陶瓷的结构和介电性能

采用固相反应法,以立方焦绿石Bi_1.5Zn_1.0Nb_1.5O₇（BZN）为配方基础,通过改变Bi³⁺离子与O^2-离子的浓度,形成非化学计量比Bi_1.5+xZN_1.0Nb_1.5O_7+1.5x（x=0.075,0.15）陶瓷。研究了不同Bi含量和烧结温度对BZN陶瓷的结构、微观形貌以及介电性能的影响。结果表明制备的非化学计量比BZN陶瓷在不高于1050℃时,呈现焦绿石单相结构;随着烧结温度增加到1100℃,x=0.075,出现ZnO杂相;x=0.15,出现Bi₂O₃杂相。随着x值的增大,BZN陶瓷样品的晶格常数、密度以及介电常数都逐渐增加。     

Ferroelectric and Piezoelectric Properties of Na1−xBaxNb1−xTixO3 Ceramics

Piezoelectric ceramics Na_{1− x} Ba _x Nb_{1− x} Ti _x O₃ with low BaTiO₃ concentrations x have been prepared by the solid-state reaction method, and their ferroelectric and piezoelectric properties have been studied. The ceramics are classic ferroelectrics when x ≤0.10, and the ferroelectric–paraelectric phase transition becomes diffusive when x ≥0.15. A low doping level of BaTiO₃ changes the NaNbO₃ ceramics from antiferroelectric to ferroelectric. With the increase in BaTiO₃ doping level, the Curie temperature of ceramics decreases linearly and the remnant polarization and coercive field also decrease, while their dielectric constant increases. Na_0.9Ba_0.1Nb_0.9Ti_0.1O₃ ceramics show the largest piezoelectric constant d ₃₃ (147 pC/N) and good sinterability, suggesting that it is a good candidate for lead-free piezoelectric ceramics.     

氧基电解质La_(10-x)V_x(SiO_4)_6O_(3+x)的制备及性能测试(英文)

Apatite-lanthanum silicate has attracted considerable interest in recent years due to its high oxide ion conductivity.In this paper,V-doped samples La10-xVx(SiO4) 6O3+x(0≤x≤1.5) were prepared by sol-gel method and the influences of V-dopant content on calcining temperature and conductivity were reported.The samples were characterized by thermal analysis(TG-DSC) ,X-ray diffraction(XRD) and scanning electron micrograph(SEM) . The apatite was obtained at 800°C,a relatively low temperature in comparison to 1500°C with the conventional solid-state method.The ceramic pellets sintered at 1200°C for 5 h showed a higher relative density than La9.33Si6O26 pellets sintered at 1400°C for 20 h.The conductivities of samples were measured by electrochemical impedance spectroscopy.The conductivity was improved with the increase of V-dopant content on La site.     

Microstructure and Electrical Properties of [(K0.50Na0.50)0.95−xLi0.05Agx](Nb0.95Ta0.05)O3 Lead-Free Ceramics

[(K_0.50Na_0.50)_{0.95− x} Li_0.05Ag _x ](Nb_0.95Ta_0.05)O₃ (KNLNANT- x ) lead-free piezoelectric ceramics were prepared by normal sintering. Effects of the Ag content on the microstructure and electrical properties of KNLNANT- x ceramics were systematically investigated. It is found that the ceramics with x =0.03 exhibit relatively good electrical properties along with high Curie temperature: ( d ₃₃∼252 pC/N, T _c∼438°C, k _p∼45.4%, P _r∼30.1 μC/cm², E _c∼13.8 kV/cm, ɛ_r∼1030, and tan δ∼2.6%). The related mechanism for enhanced electrical properties of the ceramics was also discussed. These results show that KNLNANT-0.03 ceramic is a promising candidate material for high temperature lead-free piezoelectric ceramics.