离子对(Nb5+-Cr3+)掺杂对0.93Bi0.5Na0.5TiO3-0.07BaTiO3陶瓷微观结构和电学性能的影响

采用固相烧结法制备(Bi_0.5Na_0.5)_0.93Ba_0.07Ti_1-x(Nb_0.5Cr_0.5)_xO₃(摩尔分数x=0%、0.5%、1%、2%、2.5%、5%)(简称BNBT-xNC)无铅压电陶瓷,研究离子对(Nb⁵⁺-Cr³⁺)对0.93Bi_0.5Na_0.5TiO₃-0.07BaTiO₃(简称BNT-7BT)陶瓷微观结构、介电、铁电和应变性能的影响。结果表明,所有组分为伪立方相。随着离子对(Nb⁵⁺-Cr³⁺)含量增加,BNBT-xNC陶瓷的铁电弛豫特性明显改变,在较低掺杂浓度下(0%≤x≤1%)为非遍历弛豫态,随含量增加(1%≤x≤2%),出现非遍历-遍历弛豫态共存,最后转变为遍历弛豫态(2.5%≤x≤5%);陶瓷从铁电态向弛豫态转变,应变性能先增加后降低,最大应变S_max和逆压电常数d^*₃₃在x=2%时达到最大,分别为0.22%和431 pm/V。     

0.06BiYbO3-0.94Pb(Zr0.48Ti0.52)O3三元系压电陶瓷的氧化物掺杂改性研究

针对新一代声波测井仪器对其核心元件压电陶瓷兼具高居里温度、高压电系数以及高稳定性要求的迫切需求,本文采用传统的固相反应-无压烧结技术制备了一种0.06BiYbO₃-0.94Pb(Zr_0.48Ti_0.52)O₃(BY-PZT)三元系压电陶瓷,并研究了四种氧化物掺杂对其微观结构及电学性能的影响。由XRD和SEM表征可知所有样品均呈纯四方相钙钛矿结构,掺杂Cr₂O₃的样品平均晶粒尺寸最大。介电温谱和谐振频谱研究证实四种氧化物掺杂均能提高其介电性能的温度稳定性。掺杂La₂O₃的样品介电常数温度系数(Tk_ε)最低,掺杂MnO₂的样品机械品质因素(Q_m)最高,而掺杂CeO₂的样品抗热退极化性能最好。高温复阻抗(Cole-Cole图)分析表明,Cr₂O₃掺杂能够显著提高BY-PZT陶瓷的高温电阻率,陶瓷在高温下的电导行为主要由晶界响应控制。综合来看,掺杂La₂O₃的样品兼具高居里温度(T_C=397 ℃)和高压电系数(d₃₃=290 pC/N),并且在300 ℃退火4 h后d₃₃仍能保持在270 pC/N左右,有望在极限工作温度为300 ℃的高温压电器件中获得应用。     

Co2O3掺杂对(Na0.8K0.2)0.5Bi0.5TiO3陶瓷结构与电性能的影响

采用传统固相法制备了(Na0.8K0.2)0.5Bi0.5TiO3+xmol%Co3+(BNKT-xCo,x=0-8)无铅压电陶瓷,研究了Co2O3掺杂对BNKT陶瓷的显微结构与电学性能的影响。研究表明:适量的Co2O3掺杂促进了晶粒生长,纯BNKT陶瓷样品在介电温谱上有2个介电反常峰Td和Tm,Co2O3掺杂后使所有陶瓷样品的第一个介电反常峰Td消失,表明Co3+抑制铁电-反铁电相变。室温下样品的介电、铁电和压电性能表明Co2O3起硬性掺杂效应。当x=7时陶瓷样品电性能最佳,其中机械品质因子Qm=498,介电损耗tanδ=2.3%(1kHz),压电常数d33=103pC/N,平面机电耦合系数kp=27%。     

Pb(Mg1/3Nb2/3)O3-PbZrO3-PbTiO3压电陶瓷的电学性能研究

采用固相烧结法制备了0.40Pb(Mg1/3Nb2/3)O3-(0.6-x)PbZrO3-xPbTiO3压电陶瓷,系统研究了其组分变化对晶体结构、介电和压电性能的影响。研究结果表明,所有样品均属于钙钛矿结构,无第二相产生。随着组分的变化,存在三方相向四方相的转变,并且在x = 0.38附近获得准同型相界组分,呈现出最优的电学性能,最高的压电系数d33 = 520 pC/N,居里温度TC = 238 °C,平面机电耦合系数kp = 0.60,厚度机电耦合系数kt = 0.52,纵向机电耦合系数k33 = 0.73。     

镧掺杂PMN-PT陶瓷在准同型相界处的相组成调控

采用两步预烧工艺制备Pb_{0.962 5}La_0.025(Mg_1/3Nb_2/3)_1-zTi_zO₃(z=0.28、0.29、0.30、0.31)陶瓷,其准同型相界(MPB)的化学组成位于PbTiO₃含量为0.29 mol和0.30 mol附近。选取准同型相界两侧的化学组成,制备四方晶相Pb(Mg_1/3Nb_2/3)_0.66Ti_0.34O₃和三方晶相Pb_1-1.5xLa_x(Mg_1/3Nb_2/3)_1-yTi_yO₃(x=0.083 3~0.041 7,y=0.206 7~0.273 3)陶瓷粉体。将两种晶相粉体按照设计比例(三方晶相摩尔分数w=0.3、0.4、0.5、0.6)混合,干压成型,烧结成化学组成相同、晶相占比不同的Pb_{0.962 5}La_0.025(Mg_1/3Nb_2/3)_0.70Ti_0.30O₃陶瓷。研究了晶相组成对陶瓷压电性能、介电性能、铁电性能的影响。结果表明,高温烧结后,陶瓷中的三方晶相和四方晶相占比与配料比基本一致。当w=0.5时,1 250 ℃烧结陶瓷中三方晶相与四方晶相含量占比分别为0.47、0.53,晶粒平均尺寸为(5.24±0.23) μm,相对密度为96.76%。陶瓷的压电应变常数d₃₃、径向机电转换系数k_p、厚度机电转换系数k_t、相对介电常数ε_r、剩余极化强度P_r和场致应变系数S(1 Hz、3.5 kV/mm)分别为1 014 pC/N、0.67、0.64、10 955、24 μC/cm²和0.21%。该方法可人为调控化学组成位于准同型相界的陶瓷的晶相占比。     

Co、Sm共掺杂PZN-PZT压电陶瓷的低温烧结与电性能研究

试验采用传统固相法，成功制备出Co、Sm共掺杂的Pb_0.95Ba_0.05(Zn_1/3Nb_2/3)_0.2(Zr_0.52Ti_0.48)_0.8O₃+0.6mol%Co₂O₃+0.04mol%Sm₂O₃三元系压电陶瓷。研究分析了不同烧成温度下PZN-PZT压电陶瓷材料的压电性能、介电性能、相组成及其微观结构。结果显示，Co、Sm共掺杂不仅改善了PZN-PZT的压电、介电综合性能：d₃₃=301 p C/N,K_p=0.72,ε_r=1486.46,tanδ=0.11%,Q_m=515，而且将材料的烧成温度降低到950℃。     

铈掺杂PZN-PZT三元系压电陶瓷的烧结特性研究

采用传统的固相反应法制备了掺杂0.2 wt.%CeO₂的0.3Pb(Zn_1/3Nb_2/3)O₃-0.7Pb(Zr_0.52Ti_0.48)O₃(0.3PZN-0.7PZT-0.2Ce)三元系压电陶瓷,并研究了烧结温度(1190～1260℃)对其相结构、微观形貌以及电学性能的影响。XRD和SEM分析发现:所有烧结样品均呈纯的钙钛矿相结构,随着烧结温度的升高,陶瓷样品的相结构从三方相逐渐转变为四方相,1230℃烧结得到的样品由三方相和四方相共存;当烧结温度高于1230℃过后,晶粒开始显著长大,直至液相始出现。介电温谱研究证实:随着烧结温度的升高,0.3PZN-0.7PZT-0.2Ce陶瓷的居里温度(Tc)逐渐升高而介电损耗因子(tan δ)逐渐降低,1230℃烧结得到的样品介电常数(ε_r)最大而温度系数(TK_ε)最小。压电性能以及谐振-反谐振测试表明:提高烧结温度有助于提升陶瓷的压电性能(d     

ABO3型化合物掺杂KNN基无铅压电陶瓷的研究进展

KNN基无铅压电陶瓷以其较高的居里温度、低的介电常数和高的机电耦合系数等特点,近年来备受研究人员的关注。本文结合近几年来相关文献的报道,综合分析了在KNN基无铅压电陶瓷中添加ABO₃型合物对其电学性能的影响,展望了KNN基无铅压电陶瓷将来的发展趋势。     

掺杂钛锡酸钡基陶瓷的制备及电性能研究

采用固相合成工艺制备了Li-Al(简称LA)掺杂Ba_1-x(LA)_x(Ti_0.91Sn_0.09)O₃-0.6%MnO²陶瓷,研究了LA掺杂量对钛锡酸钡基陶瓷物相组成、相对密度、晶粒尺寸、介电性能和压电性能的影响。结果表明,LA掺杂钛锡酸钡基陶瓷都为ABO₃型钙钛矿结构,(022)和(200)晶面的衍射峰会随着掺杂量增加而逐渐右偏移;随着掺杂量x从0增加至2.5%,LA掺杂钛锡酸钡基陶瓷的相对密度先增后减,在x=0.5%时取得最大值(93.7%)。相同频率下LA掺杂钛锡酸钡基陶瓷的介电常数从大至小顺序为：0.5%>1.0%>0>1.5%>2.0%>2.5%;LA掺杂量为0.5%时钛锡酸钡基陶瓷的介电常数最高。随着LA掺杂量从0增加至2.5%,压电系数d₃₃、平面机电耦合系数K_p和相位角θ_max都表现为先增后减趋势,在x=0.5%时取得最大值。...     

Fe2O3原料的预处理对0.7BiFeO3-0.3BaTiO3陶瓷绝缘性与电性能的影响

BiFeO₃基无铅压电陶瓷常因漏电流较大而压电性能欠佳,然而,改善其绝缘性和电性能的方法都较为复杂,限制了其产业化生产与应用。本工作在不针对0.7BiFeO₃-0.3BaTiO₃陶瓷进行组分掺杂以及气氛烧结的条件下,仅通过简单的原料预处理(改变Fe₂O₃原料的干燥时间)即实现了其高绝缘性与高压电性能。研究结果表明,0.7BiFeO₃-0.3BaTiO₃陶瓷的晶粒尺寸和绝缘性随Fe₂O₃原料干燥时间的增加而增大,同时其电性能及温度稳定性也随之增强。当原料干燥时间为192 h时,样品晶粒尺寸最大,绝缘性最好,同时其压电性能(d₃₃=203 pC/N,k_p=0.33)和居里温度(T_c=460 ℃)也达到最佳。这为今后BiFeO₃基陶瓷压电性能的研究提供了一个新思路。     

Structural and Electrical Properties of Er2O3-Doped Na1/2Bi1/2TiO3 Lead-Free Piezoceramics

Sodium bismuth titanates Na_1/2Bi_1/2TiO₃ (NBT) doped with 0–3 wt% Er₂O₃ were prepared by the conventional solid-state reaction method. The X-ray diffraction results revealed that the sintered Er-doped NBT ceramics exhibited a pure perovskite structure with Er³⁺ concentrations ranging from 0 to 1 wt%. At a low Er₂O₃ concentration, the Er-doped NBT ceramics showed enhanced electrical properties with dielectric constant ɛ₃₃^T/ɛ₀=636, a low dielectric dissipation factor (tan δ=3.3%), a low coercive field ( E _c=4.56 kV/mm), and a high piezoelectric constant ( d ₃₃=75 pC/N). The relationship between the composition and properties of Er-doped NBT ceramics has been discussed.     

Piezoelectric properties of low temperature sintering in Pb(Zr,Ti)O3–Pb(Zn,Ni)1/3Nb2/3O3 ceramics for piezoelectric transformer applications

In this study, in order to develop low-temperature sintering ceramics for a multilayer piezoelectric transformer application, we explored CuO and Bi₂O₃ as sintering aids at low temperature (900 °C) sintering condition for Sb, Li and Mn-substituted 0.8Pb(Zr_0.48Ti_0.52)O₃–0.16Pb(Zn_1/3Nb_2/3)O₃–0.04Pb(Ni_1/3Nb_2/3)O₃ ceramics. These substituted ceramics have excellent piezoelectric and dielectric properties such as d₃₃  347 pC/N, k_p  0.57 and Q_m  1469 when sintered at 1200 °C. The addition of CuO decreased the sintering temperature through the formation of a liquid phase. However, the piezoelectric properties of the CuO-added ceramics sintered below 900 °C were lower than the desired values. The additional Bi₂O₃ resulted in a significant improvement in the piezoelectric properties. The composition Sb, Li and Mn-substituted 0.8Pb(Zr_0.48Ti_0.52)O₃–0.16Pb(Zn_1/3Nb_2/3)O₃–0.04Pb(Ni_1/3Nb_2/3)O₃ + 0.5 wt% CuO + 0.5 wt% Bi₂O₃ showed the value of k_p = 0.56, Q_m = 1042 (planar mode), d₃₃ = 350 pC/N, when it was sintered at 900 °C for 2 h. These values indicated that the newly developed composition might be suitable for multilayer piezoelectric transformer application.     

Sintering and Electrical Properties of Lead-Free Na0.5K0.5NbO3 Piezoelectric Ceramics

Lead-free Na_0.5K_0.5NbO₃ (NKN) piezoelectric ceramics were fairly well densified at a relatively low temperature under atmospheric conditions. A relative density of 96%–99% can be achieved by either using high-energy attrition milling or adding 1 mol% oxide additives. It is suggested that ultra-fine starting powders by active milling or oxygen vacancies and even liquid phases from B-site oxide additives mainly lead to improved sintering. Not only were dielectric properties influenced by oxide additives, such as the Curie temperature ( T _c) and dielectric loss ( D ), but also the ferroelectricity was modified. A relatively large remanent polarization was produced, ranging from 16 μC/cm² for pure NKN to 23 μC/cm² for ZnO-added NKN samples. The following dielectric and piezoelectric properties were obtained: relative permittivity ɛ ^T ₃₃/ɛ ₀ =570–650, planar mode electromechanical coupling factor, k _p=32%–44%, and piezoelectric strain constant, d ₃₃=92–117 pC/N.     

ZnO-B2O3玻璃对Li2Zn3Ti4O12-CaTiO3复合陶瓷低温烧结及性能的影响

采用传统固相反应法制备0.94Li₂Zn₃Ti₄O₁₂-0.06CaTiO₃(LZT-CT)复合陶瓷,采用高温熔融法制备ZnO-B₂O₃(ZB)玻璃;以ZB玻璃为烧结助剂,研究了添加不同质量分数(x=0.5%、1.0%、1.5%、2.0%和2.5%)的ZB玻璃对LZT-CT复合陶瓷的烧结特性、物相组成、微观结构以及微波介电性能的影响。结果表明:ZB玻璃能有效地将LZT-CT复合陶瓷的烧结温度从1 175 ℃降低到875 ℃,并促进了LZT-CT复合陶瓷的致密化。当ZB玻璃掺量x≤2.5%时,LZT-CT复合陶瓷中除了LZT、CT相,没有出现其他新相。随着ZB玻璃添加量增加,复合陶瓷的体积密度、介电常数(ε_r)、品质因数(Q×f)均先增加后减小,谐振频率温度系数(τ_f)变化不大,在(-2.25~4.51)×10^-6/℃波动。当ZB玻璃掺量为2.0%时,LZT-CT复合陶瓷在875 ℃烧结2 h,获得最大体积密度(4.22 g/cm³)以及优异的微波介电性能,ε_r=23.9,Q×f=58 595 GHz,τ_f=-0.14×10^-6/℃。     

Dielectric and Ferroelectric Properties of Ceramics in the Pb(Zn 1/3Nb2/3)O3-BaTiO3-PbTiO3 System

The use of Pb(Zn_1/3Nb_2/3)O₃ ceramics is restricted by the formation of a pyrochlore phase detrimental to both dielectric and piezoelectric properties. Recently it has been shown that a 6 mol% addition of BaTiO₃ to PZN suppresses the formation of pyrochlore phase. Phase relations and dielectric properties of ceramics in the PZN-BT-PT system are reported here. Compositions with the perovskite structure, having high dielectric constant and low temperature coefficient of capacitance, have been identified.     

Piezoelectric properties of Pb(Mn1/3Nb2/3)O3–PbZrO3–PbTiO3 ceramics with sintering aid of 2CaO–Fe2O3 compound

Since the electromechanical devices move towards enhanced power density, high mechanical quality factor (Q_m) and electromechanical coupling factor (k_p) are commonly needed for the high powered piezoelectric transformer with Q_m≥2000 and k_p=0.60. Although Pb(Mn_1/3Nb_2/3)O₃–PbZrO₃–PbTiO₃ (PMnN–PZ–PT) ceramic system has potential for piezoelectric transformer application, further improvements of Q_m and k_p are needed. Addition of 2CaO–Fe₂O₃ has been proved to have many beneficial effects on Pb(Zr,Ti)O₃ ceramics. Therefore, 2CaO–Fe₂O₃ is used as additive in order to improve the piezoelectric properties in this study. The piezoelectric properties, density and microstructures of 0.07Pb(Mn_1/3Nb_2/3)O₃–0.468PbZrO₃–0.462PbTiO₃ (PMnN–PZ–PT) piezoelectric ceramics with 2CaO–Fe₂O₃ additive sintered at 1100 and 1250 °C have been studied. When sintering temperature is 1250 °C, Q_m has the maximum 2150 with 0.3 wt.% 2CaO–Fe₂O₃ addition. The k_p more than 0.6 is observed for samples sintered at 1100 °C. The addition of 2CaO–Fe₂O₃ can significantly enhance the densification of PMnN–PZ–PT ceramics when the sintering temperature is 1250 °C. The grain growth occurred with the amount of 2CaO–Fe₂O₃ at both sintering temperatures.     

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.     

Complex piezoelectric, elastic, and dielectric coefficients of La-DOPED 0.93 Pb(Mg1/3Nb2/3)O3:0.07 PbTiO3 under DC bias

Complex material parameters (piezoelectric coefficient d₃₁, elastic s₁₁^E, and the dielectric constant K₃₃) of the relaxor ferroelectric ceramic (1-x) Pb(Mg_1/3Nb_2/3)O₃-xPbTiO₃(x =.07) with 1% La (lanthanum) were measured as a function of bias field using a bar resonator. The values of the dielectric and piezoelectric phase angles are found to be comparable (i.e., around 0.04 for a d.c. bias field of 2.5 kV/cm), while the elastic phase angle is an order of magnitude smaller (0.001 for the same d.c. bias). For comparison of complex material parameters found from bar resonators, a sample in the form of a small disk is used to measure Poisson's ratio as well as the real components of the piezoelectric and elastic coefficients as a function of bias field.     

Microwave Dielectric Properties and Low-Temperature Sintering of Ba0.60Sr0.40TiO3 Ceramics

In the present work, the sintering behaviors and dielectric properties of Ba_0.60Sr_0.40TiO₃ (BST) ceramics with the addition of BaCu(B₂O₅) were investigated in detail. The results indicated that the addition reduced the sintering temperature of BST by about 500°C. It was suggested that a liquid phase BaCu(B₂O₅) assisted the densification of BST ceramics at lower temperatures. For a low-level BaCu(B₂O₅) addition (2.0 mol%), the BST sample sintered at 950°C for 5 h displayed good dielectric properties, with a moderate dielectric constant (ɛ=2553) and a low dielectric loss (tan δ=0.00305) at room temperature and at 10 kHz. The sample showed 45.9% tunability at 10 kHz under a dc electric field of 30 kV/cm. At the frequency of 0.984 GHz, BST-added 2.0 mol% BaCu(B₂O₅) possessed a dielectric constant of 2204 and a Q value of 146.7.     

Piezoelectric Properties of Pb[Zr0.45Ti0.5-xLux(Mn1/3Sb2/3)0.05]O3 Ceramics

The piezoelectric properties of Pb[Zr_0.45Ti_{0.5- x} Lu _x (Mn_1/3-Sb_2/3)_0.05]O₃ ceramics, with 0 lessthan equal to x lessthan equal to 0.03, have been investigated. The partial substitution of Ti⁴⁺ with Lu³⁺ permitted improvement of the electromechanical coupling factor ( k _p), the dielectric constant (epsilon^T₃₃), and the piezoelectric constant ( d ₃₃), while the dielectric loss (tan delta) increased and the mechanical quality factor ( Q _m) decreased with an increase of x . A pertinent piezoelectric material for actuator applications was Pb[Zr_0.45Ti_0.48Lu_0.02(Mn_1/3Sb_2/3)_0.05]O₃, and the piezoelectric properties were k _p = (58.5 ± 0.5)%, epsilon^T₃₃ = 32 ± 25, d ₃₃ = (373 ± 6) 10^-12 C/N, Q _m = 714 ± 22, and tan delta = (0.98 ± 0.03)%.