Cr2O3掺杂Pb(Mn1/3Sb2/3)0.05Zr0.47Ti0.48O3压电陶瓷的性质

探讨了Cr2O3掺杂对锑锰锆钛酸铅Pb（Mn1/3Sb2/3）0.05Zr0.47Ti0.48O3（简称PMSZT）压电陶瓷性能影响.通过X射线衍射,电子顺磁共振以及扫描电镜分析了PMSZT＋z Cr2O3（z=0.2%～0.8%,质量分数）陶瓷的相组成,元素价态以及显微结构.结果表明：合成温度900℃保温2 h后,可以得到钙钛矿结构.随着Cr2O3掺杂量的增大,四方相的含量减少,准同相界向三方相移动.掺杂Cr2O3的质量分数为0.6%时：相对介电常数εr=1 650,介电损耗tanδ=0.006,压电常数d33=328 pC/N,机电耦合系数Kp=0.63,机械品质因数Qm=2 300,电性能优于Cr2O3掺杂量为0.2%,0.4%,0.8%的样品,但比未掺杂时的稍差.随着Cr2O3掺杂量的增加,PMSZT陶瓷的Curie温度降低,谐振频率变化率随温度变化由正变负.     

Structures and Properties of Pb(Zr0.5Ti0.5)O3−Pb(Zn1/3Nb2/3)O3− Pb(Ni1/3Nb2/3)O3 Ceramics for Energy Harvesting Devices

Piezoelectric ceramics with large energy density coefficient d₃₃·g₃₃ value have been found suitable for piezoelectric energy harvesting applications. In this study, the phase structures and piezoelectric properties of xPb(Zr_0.5Ti_0.5)O₃?yPb(Zn_1/3Nb_2/3)O₃?(1?x?y)Pb(Ni_1/3Nb_2/3)O₃ (xPZT?yPZN?(1?x?y)PNN) ceramic were investigated with systematically varying PZN and PNN components. The ternary phase diagram of PZT?PZN?PNN system was illustrated and the composition region of morphotropic phase boundary (MPB) was determined. Piezoelectric and dielectric measurements verify that the materials in MPB region all present large d₃₃ and d₃₃·g₃₃ values. In particular, very high d₃₃·g₃₃ coefficients of 20162.2 × 10^?15 m²/N and 21026.3 × 10^?15 m²/N are observed from samples 0.75PZT?0.15PZN?0.1PNN and 0.8PZT?0.05PZN?0.15PNN with compositions located on the rhombohedral phase side near MPB because the dielectric coefficient ε₃₃^T/ε₀ decreases faster than the d₃₃ coefficient at this side.     

B位掺杂对Pb[(Mn1/3Nb2/3)0.5(Mn1/3Sb2/3)0.5]x(Zr0.825Ti0.175)1-xO3系陶瓷铁电畴反转的影响

用传统陶瓷工艺制备了Pb[(Mn1/3Nb2/3)0.5(Mn1/3Sb2/3)0.5]x(Zr0.825Ti0.175)1-xO3(其中x为B位掺杂的摩尔分数,下同)系铁电陶瓷,研究了室温条件下电滞回线的特性.结果显示:当x≤0.1时,电滞回线出现"束腰";当x=0.2时,"束腰"消失.用X射线光电子能谱、X射线衍射分析手段研究了"束腰"现象,并用氧缺位内偏场理论分析该现象的微观机理.结果表明:过量Mn偏析于晶界,使材料的晶界具有P型导电性,偏析Mn的量越多,晶界p型导电性越强,氧缺位钉扎电畴的能力下降,电畴容易反转,进而导致"束腰"现象消失.另外,随着x增大,剩余极化强度先增大后减小,矫顽场逐渐增大.     

Co_2O_3掺杂对Pb(Ni_(1/3)Nb_(2/3))(Zr,Ti)O_3压电陶瓷电学性能及介电弛豫的影响

采用氧化物粉末固相烧结法制备Pb(Ni_(1/3)Nb_(2/3))0.5(Zr_(0.3)Ti_(0.7))0.5O_3–w Co_2O_3(0.5PNN–0.5PZT–w Co)压电陶瓷。研究了Co_2O_3掺杂含量对0.5PNN–0.5ZT压电陶瓷相结构、显微组织、电学性能及介电弛豫的影响。结果表明:Co~(3+)掺杂进入主晶体结构中占据了B位。当0.2%≤w≤0.8%(质量分数)时,样品为单一稳定的钙钛矿结构,存在准同型相界;通过修正Curie–Weiss定律,较好地描述了陶瓷弥散相变的特征,弥散相变系数γ随着Co_2O_3掺杂量的增加,先增加后减小,当w=0.4%时,γ达到最大值,表明样品的介电弛豫特征更为明显。样品具有最佳的综合电学性能,压电常数d33=675 p C/N,机电耦合系数kp=60%,介电常数εr和介电损耗tanδ分别约为5 765和1.16%,说明介电弛豫行为与电学性能相关。     

Abnormal frequency dependent polarization fatigue behavior in aged Pb(Mn1/3Sb2/3)O3-Pb(Zr,Ti)O3 ferroelectric ceramics

The fatigue behavior of 0.05Pb(Mn_1/3Sb_2/3)O₃–0.50PbZrO₃–0.45PbTiO₃ ceramics (abbreviated as PMS-PZT) is investigated. Special attention is paid to the effect of applied electric frequency on the evolution of polarization-electric field, strain-electric field hysteresis loops as well as the parameters of remnant polarization, internal bias field and coercive field extracted directly from the former hysteresis loops or calculated according to these loops. It is found that the fatigue behavior is different from that of donor doped Pb(Zr,Ti)O₃ (PZT) ceramics demonstrated by the tendency of increasing remnant polarization, the decreased internal bias field, decreased asymmetry of polarization-electric and strain-electric loops with increasing fatigue duration when PMS-PZT ceramics fatigued at lower frequency (i.e. 5 Hz or 500 Hz). The dynamic of oxygen vacancies under the application of bipolar electric field is supposed to be associated with the abnormal fatigue behavior. In addition, no matter at which cyclic frequency samples fatigued, coercive field shows the tendency of decrease with increasing fatigue duration except for sample fatigued at 5 kHz in which coercive field first decreases and then increases. According to phase structure and the empirical Rayleigh analysis, phase transition during fatigue treatment is supposed to be account for the decrease of coercive field.     

Dielectric and Piezoelectric Properties of (1−x)K0.5Bi0.5TiO3–xBa(Ti0.8Zr0.2)O3 Ceramics

The properties of relaxor ceramics in the compositional series (1?x)K_0.5Bi_0.5TiO₃–xBa(Ti_0.8Zr_0.2)O₃ have been investigated. Values of T_m, the temperature of maximum relative permittivity, decreased from 380°C at x = 0.0 to below room temperature for x > 0.7. Compositions x = 0.1 and 0.2 were piezoelectric and ferroelectric. The maximum value of d₃₃ piezoelectric charge coefficient, 130 pC/N, and strain, 0.14%, occurred at x = 0.1. Piezoelectric properties of x = 0.1 were retained after thermal cycling from room temperature to 220°C, consistent with results from high‐temperature X‐ray diffraction indicating a transition to single‐phase cubic at ~300°C.     

Effects of Nb,Mn doping on the Structure,Piezoelectric, and Dielectric Properties of 0.8Pb(Sn0.46Ti0.54)O3–0.2Pb(Mg1/3Nb2/3)O3 Piezoelectric Ceramics

Nb and Mn were doped, respectively, to 0.8Pb(Sn_0.46Ti_0.54)O₃–0.2Pb(Mg_1/3Nb_2/3)O₃ (PST–PMN) to improve electrical properties for meeting the requirement in various fields. The additions of Nb and Mn influence in a pronounced way the structure, and improve the densities of the ceramics. Nb‐doped PST–PMN increased the piezoelectric coefficient d₃₃, planar electromechanical coupling k_p, and relative dielectric constant ε, indicating “soft” piezoelectric behavior. Mn doping played a “hard” part, which significantly enhanced the mechanical quality factor Q_m without deteriorating other piezoelectric properties. The most excellent properties of Nb‐doped PST–PMN were obtained with doping amount of 0.75 mol%, specifically d₃₃, k_p, being on the order of 455 pC/N, 57.5% and 3560, respectively. The addition of 0.75 mol% Mn for PST–PMN presented the optimum electrical properties, with Q_m of 554, d₃₃ of 430 pC/N, k_p of 57.0%, ε of 2770. It was proposed that the addition of Nb, Mn generated different defect dipoles involved in the domain walls motion and intrinsic piezoelectric responses, leading to different effects on electrical properties.     

Structural and Physical Properties of Nd-Doped Pb(Zr0.52Ti0.48)O3 Ceramics

Lead zirconate titanate (PZT) ceramics (Zr/Ti = 52/48) have been modified with different quantities of neodymium oxide (Nd₂O₃). The preparation was carried out via the solid-state-reaction route. The samples were calcined and sintered at 850°C and 1200°C, respectively. The structural evolution and the microstructure were investigated using an X-ray diffractometer (XRD) and a scanning electron microscope (SEM), respectively. The physical properties such as dielectric constants, piezoelectric coefficients, density etc. were also studied.     

Effect of MnO2 on the microstructure and electrical properties of 0.83Pb(Zr0.5Ti0.5)O3-0.11Pb(Zn1/3Nb2/3)O3-0.06Pb(Ni1/3Nb2/3)O3 piezoelectric ceramics

A sample of 0.83Pb(Zr_0.5Ti_0.5)O₃-0.11Pb(Zn_1/3Nb_2/3)O₃-0.06Pb(Ni_1/3Nb_2/3)O₃ (PZNNT) to which MnO₂ was added, with a high mechanical quality factor (Q_m) and a good transduction coefficient (d₃₃×g₃₃), were systematically investigated. Based on the SEM analysis there existed two kinds of “secondary phases”, Rich Ti and Rich Zn phases, which arose due to the B-site substation of PZNNT-based ceramics by manganese ions. One phase was due to the Mn³⁺ replacing the Ti⁴⁺ to create oxygen vacancies and induce the hardening effect. Another phase was due to the Mn²⁺ replacing the Zn-site to stabilize the perovskite phase. When the addition of MnO₂ reached the solubility limit of 1.5 mol% in the PZNNT-based ceramics, the sample showed optimal electrical properties (Q_m=357, d₃₃×g₃₃=9859 × 10⁻¹⁵ m²/N, k_p=0.56), which suggested its potential application for piezoelectric energy harvesting in larger field excitation environments.     

Fabrication and post heat treatment of 0.5Pb (Mg1/3Nb2/3)O3-0.5Pb(Zr0.48Ti0.52)O3 coatings by supersonic plasma spray

Pb(Mg_1/3Nb_2/3)O₃-Pb(Z_r0.48Ti_0.52)O₃ coatings were obtained by supersonic plasma spray. With subsequent heat treatment, compact structure and typical tetragonal phase were obtained, and therefore dielectric performance (ε_r ≈ 915 at ambient temperature) have been significantly improved. The reason for successfully promote the properties is attributed the elimination of defects, amorphous and pyrochlore phase. Detail analyses were conducted on the variation of defects (pores and micro-cracks) and phase (amorphous, pyrochlore) of coatings after treated at elevated temperature. With the analyses, the existence of pyrochlore phase and ZrO₂ are attributed to the incongruent melting behavior. Inhibition of grain growth is attributed to the accumulation of ZrO₂ in the grain boundary. The results also suggest the subsequent change from pseudocubic to tetragonal at elevated temperature.     

Enhanced and stable strain memory in Mn‐doped Pb(Mn1/3Sb2/3)O3–Pb(Zr,Ti)O3 ceramics realized by sesquipolar loading

The negative electric field, field cycling and frequency dependence of strain memory effect in poled and aged Mn‐doped Pb(Mn_1/3Sb_2/3)O₃–Pb(Zr,Ti)O₃ (PMS–PZT) piezoceramics under sesquipolar loading were investigated. The strain memory effect of Mn‐doped PMS–PZT is especially sensitive to the applied negative electric field. Maximum strain memory of 0.32% is achieved when the negative electric field is around negative coercive field of ~2.1 kV/mm, which can be ascribed to the partially depoled state with randomized domains. And this strain memory shows very good cycling stability, varying less than 5% up to 10⁴ cycles, while almost 40% degradation is found under bipolar signal. In addition, due to the stabilized defect dipoles, the strain memory exhibits stable characteristic over a broad frequency range from 0.01 Hz to 20 Hz. The results may shed new insights into designing the novel strain memory actuators where stable strain state could be realized after the removal of electric field.     

CaTiO3对Pb0.95Ba0.05Nb2O6压电陶瓷性能的影响

采用标准电子陶瓷工艺制备了(1-x)Pb0.95Ba0.05Nb2O6-xCa0.5TiO3(x=0.01,0.02,0.03,0.04)高温压电陶瓷,研究了CaTiO3对Pb0.95Ba0.05Nb2O6陶瓷的显微组织、相结构,介电和压电性能的影响,得到了CaTiO3掺杂量与Pb0.95Ba0.05Nb2O6陶瓷性能之间的关系.X射线衍射(XRD)分析表明,CaTiO3的加入使Pb0.95Ba0.05Nb2O6很容易形成正交铁电相,而且相同方法制备纯的PbNb2O6是菱方非铁电相钨青铜结构,随着CaTiO3含量的增加,晶胞体积减小.介电温谱测试表明该改性材料具有高居里温度(Tc＞550℃).测试了不同组成陶瓷的压电性能及其热稳定性,当CaTiO3的掺人量x=0.03时,得到压电常数达到d33=69pC/N、平面机电耦合系数Kp=0.30、机械品质因子Qm=27.8、居里温度Tc=570℃的陶瓷样品,该组成具有优异的热稳定性,适合于高温(500℃)环境下使用.     

Sm掺杂Pb(Mg1/3Nb2/3)O3-PZT压电陶瓷的研究

本文通过一步反应合成法制备了铌镁-锆钛酸铅(Pb(Mg_1/3Nb_2/3)O₃-Pb(Zr,Ti)O₃,PMN-PZT)压电陶瓷,研究了稀土元素钐(Sm)掺杂对PMN-PZT(x%(摩尔分数)Sm-PMN-PZT)结构与电学性能的影响规律,得到了具有高压电性、高机电耦合系数和高居里温度的压电陶瓷。当x=2.0时,压电常数d₃₃=611 pC/N,机电耦合系数k_p=0.68,介电损耗tan δ=1.65%,相对介电常数ε_r=2 650,居里温度T_C=283 ℃。测试压电陶瓷电致应变性能,在3 kV/mm下单极电致应变达到0.20%,显示出其大应变材料的特征。结果表明,Sm掺杂PMN-PZT压电陶瓷具有优异的综合电学性能,有望在换能器、传感器以及致动器等领域广泛应用。     

Metastable Ferroelectric Phase Induced by Electric Field in xPb(Zn1/3Nb2/3)O3–(1–x)Pb(Zr0.95Ti0.05)O3 Ceramics

A xPb(Zn_1/3Nb_2/3)O₃–(1–x)Pb(Zr_0.95Ti_0.05)O₃ (xPZN–(1–x) PZT) system close to antiferroelectric–ferroelectric (AFE–FE) morphotropic phase boundary has been prepared and investigated. The XRD results reveal PZN addition induces a phase transition from the orthorhombic (AFE) to rhombohedral (FE) phase through a phase coexistence region (AFE+FE). The polarization–electric field (P–E) measurements indicate that the AFE phase can be induced into a metastable FE (FE_m) phase. And the FE_m can recover to AFE around a critical temperature indicated by temperature‐dependent P–E loops. A composition‐temperature phase diagram was generalized within a certain range of PZN content in which an AFE–FE phase boundary connecting orthorhombic antiferroelectric to rhombohedral ferroelectric phase zones is formed near room temperature.     

不同锆钛比铁铌锆钛酸铅热释电陶瓷的结构与性能

研究了Zr/Ti摩尔比对两步法合成的0.3Pb(Fe1/2Nb1/2)O3–0.7Pb(ZrxTi1-x)O3(PFNZxT1-x)复合热释电陶瓷微观结构、相构成和综合电学性能的影响。结果表明,所制备的陶瓷样品均为单一钙钛矿结构。在x=0.50处出现四方、菱方相共存的准同型相界。随着Zr/Ti摩尔比增加(x从0.50增至0.95),逐渐从两相共存变为菱方相,同时伴随晶胞体积和陶瓷晶粒尺寸的不断增大。随x增加,体系介电常数减小,介电损耗变化较小,而体系热释电系数及优值呈现出逐渐增大趋势。当Zr/Ti摩尔比在富锆的80/20~85/15之间时,材料室温热释电系数p大于11×10-8 C/(cm2·K1),探测率优值FD大于16×10-5 Pa-1/2,具有较好的综合电学性能。     

Ca含量对(Ba1-xCax)(Ti0.9Zr0.1)O3无铅压电陶瓷性能的影响

采用传统的固相法制备(Ba1-xCax)(Ti0.9Zr0.1)O3(简称BCTZ)无铅压电陶瓷.借助扫描电镜(SEM)和X射线衍射仪(XRD)等测试方法研究了Ca含量对所制备BCTZ无铅压电陶瓷显微结构和压电介电性能的影响.结果表明:随着Ca含量的增加,(Ba1-xCax)(Ti0.9Zr0.1)O3无铅压电陶瓷的晶粒尺寸先增大后减小,所制备的BCTZ陶瓷的物相都是钙钛矿结构,没有杂相;随着Ca含量的增加,BCTZ陶瓷压电常数(d33),介电常数(εr),机电耦合系数(kp)分别先增加后降低,而介质损耗(tanδ)先减小后增大.当Ca含量(x)为0.15mol时,在1450℃烧结制得的(Ba1-xCax)(Ti0.9Zr0.1)O3无铅压电陶瓷性能最佳:压电常数(d33)为363pC/N,机电耦合系数(kp)为39.63％,介电常数(εr)为4184,介质损耗(tanδ)为1.08％.     

Correlation Between Piezoelectric Properties and Phase Coexistence in (Ba,Ca)(Ti,Zr)O3 Ceramics

High piezoelectric properties are desired for lead‐free piezoelectric materials in consideration as a replacement for lead‐based materials in applications. Due to the high piezoelectric coefficient, (Ba_100?xCa_x) (Ti_100?yZr_y) O₃ (BCTZ) piezoelectric ceramics have been considered as a promising lead‐free alternate piezoelectric material. Here, six compositions were selected based on a prediction that all the compositions would have high piezoelectric coefficient at room temperature. The results confirmed all compositions exhibit well developed hysteresis loops and a large piezoelectric coefficient at room temperature. This is due to the coexistence of several phases where the major phase is likely to be orthorhombic and the second phase is proposed to be tetragonal. The phase transition was found to occur over a broad temperature range instead of at a specific temperature only. A relationship between the tetragonal–orthorhombic phase transition temperature and Ca²⁺ and Zr⁴⁺ content was proposed. This enables clear determination of BCTZ compositions with high piezoelectric coefficient at a desired operation temperature.     

Low‐Temperature Sintering and Electric Properties of Pb0.99(Zr0.95Ti0.05)0.98Nb0.02O3 Ferroelectric Ceramics with CuO Additive

The low‐temperature sintering and electric properties of Pb_0.99(Zr_0.95Ti_0.05)_0.98Nb_0.02O₃ (PZTN 95/5) ferroelectric ceramics with CuO addition was investigated. The CuO addition significantly promoted the densification and reduced the sintering temperature of PZTN 95/5 ceramics by more than 200°C. The 0.2 wt% CuO‐added sample sintered at 1150°C exhibited the optimum relative density of 96.7% and excellent electric properties with values of P_r = 37.80 μC/cm², T_C = 223°C, ε_r = 329, and tan δ = 0.016, which were superior to that of PZTN 95/5 ceramics sintered at 1350°C.     

High-energy density of Pb0.97La0.02(Zr0.50Sn0.45Ti0.05)O3 antiferroelectric ceramics prepared by sol-gel method with low-cost dibutyltin oxide

Lead lanthanum zirconate stannate titanate (PbLa(ZrSnTi)O₃) antiferroelectric (AFE) ceramics are widely used in dielectric capacitors due to their superior energy-storage capacity. Generally, these ceramics can be synthesized by solid-state reaction and sol-gel methods. Ceramics prepared using the sol-gel method have a purer phase than those prepared using the solid-state reaction method because the sol-gel method can avoid the segregation of Sn. However, because the commonly used raw material tin acetate is very expensive, the preparation of PbLa(ZrSnTi)O₃ AFE ceramics via the sol-gel method is not cost-effective, which prevents the use of sol-gel method for manufacturing PbLa(ZrSnTi)O₃ in a large scale. In this work, low-cost dibutyltin oxide instead of expensive tin acetate is used to synthesize Pb_0.97La_0.02(Zr_0.50Sn_0.45Ti_0.05)O₃ (PLZST) nanopowders, and single-phase powders with a perovskite structure and average grain size of 200 nm are obtained at a calcination temperature of 580°C. In addition, dense PLZST AFE ceramics with a pure perovskite structure are obtained by sintering the PLZST nanopowders at temperatures as low as 1100°C. The sintered PLZST ceramics exhibit a room-temperature recoverable energy-storage density as high as 1.93 J/cm³ with an efficiency of 75%, which varies only slightly in the temperature range of 20-120°C. The high energy-storage density (>1.9 J/cm³) over a wide temperature range illustrates that the sol-gel-derived PLZST ceramics with low-cost dibutyltin oxide are quite promising for manufacturing pulse power capacitors.     

Enhanced Dielectric and Ferroelectric Properties of Pb(Mg1/3Nb2/3)0.65Ti0.35O3 Ceramics by ZnO Modification

Phase formation, microstructures, dielectric, and ferroelectric properties of ZnO‐modified Pb(Mg_1/3Nb_2/3)_0.65Ti_0.35O₃ (PMNT/xZnO, where x = 0, 0.4, 2.0, 4.0, and 11.0 mol%) ceramics were studied. A coexistence of rhombohedral and tetragonal ferroelectric phases was observed at room temperature in all samples. The ceramics with the relative densities of 93%–95% were prepared. The modification by ZnO led to an increase in grain sizes of PMNT ceramics. The maximum dielectric constant of the pure PMNT ceramic was increased with x = 0.4–4.0 mol% ZnO doping, with the highest value being observed in the 2.0 mol% sample. Both the temperature at which the transition between rhombohedral and tetragonal ferroelectric phases took place (T_R‐T) and the Curie temperature of the ceramics tended to increase with increasing x. The ferroelectric properties were enhanced with increased remanent polarization and P(E) loop squareness in the compositions with x = 0.4–4.0 mol%. However, the ferroelectric properties were attenuated with x = 11.0 mol%.