Ba(Mg1/3Nb2/3)O3-Mg4Nb2O9复相陶瓷微波介电性能研究

采用传统固相法制备了(1?x)Ba(Mg1/3Nb2/3)O3?xMg4Nb2O9 [(1?x)BMN?xM4N2,x = 0.003 ~ 0.125] 微波介质陶瓷,研究了相结构、烧结性能与介电性能随 x 的变化规律。结果表明： BMN 与 M4N2 可以两相共存,且二者间存在有限固溶,BMN 的烧结温度及高温稳定性有所降 低。随着 x 的增大,介电常数 εr和谐振频率温度系数 τf逐渐减小,Q × f 值的变化易受到 BMN 有序参数 S 的影响,高度 1:2 有序的 x = 0.026 陶瓷获得了最大 Q × f 值 125000 GHz。综合来看, 在 1320°C 下保温 4 h 烧结的 x = 0.125 样品表现出最佳的微波介电性能：εr = 26.6,Q × f = 111000 GHz,τf = 5 ppm/ºC。     

Ferroelectric to Relaxor Transition in BaTiO3–Bi(Zn2/3Nb1/3)O3 Ceramics

The (1?x)BaTiO₃–xBi(Zn_2/3Nb_1/3)O₃ (x = 0.01–0.30) ceramics were synthesized by solid‐state reactions. The solubility limit was determined to be x = 0.20. A systematic structural transition from a tetragonal phase (x ≤ 0.034), to a mixture of tetragonal and rhombohedral phases (0.038 ≤ x ≤ 0.20), and finally to a pseudocubic phase (x ≥ 0.22) at room temperature was identified. Dielectric measurement revealed a ferroelectric (x ≤ 0.04) to relaxor (x ≥ 0.06) transition with permittivity peak broadening and flattening, which was further verified by Raman spectroscopy and differential scanning calorimetry (DSC). Activation energies obtained from the Vogel–Fulcher model displayed an increasing trend from ~0.03 eV for x ~ 0.05, to unusually high values (>0.20 eV) for the compositions with x ≥ 0.15. With the increase in Bi(Zn_2/3Nb_1/3)O₃ content, the polarization hysteresis demonstrated a tendency from high nonlinearity to sublinearity coupled with the reduction in remnant polarization and coervice field. The deconvolution of the irreversible/reversible polarization contribution was enabled by first‐order reversal curve distributions, which indicates that the decreasing polarization nonlinearity with the increase in Bi(Zn_2/3Nb_1/3)O₃ concentration could be related with the change from the ferroelectric domain and domain wall contributions to the weakly coupled relaxor behaviors.     

Ln(B1/2Ti1/2)O3型微波介质陶瓷的研究进展

综述了Ln(B1/2Ti1/2)O3 (B=Mg, Zn, Co)型微波介质陶瓷的结构、低温烧结及改性研究现状. 少量烧结助剂可有效降低陶瓷的烧结温度,但有时会恶化品质因数(Q×f). 离子取代可显著提高Q×f值,对谐振频率温度系数(τf)无明显影响;而复合改性则可有效调节τf值至近0. 最后探讨了Ln(B1/2Ti1/2)O3型微波介质陶瓷研究中存在的问题和未来的发展趋势,简化和优化合成工艺、实现低温烧结和调节谐振频率温度系数、加强低温烧结、离子取代和复合改性的机理研究是未来重要的研究方向.     

Ba缺位和烧结工艺对Ba1-xZn1/3Nb2/3O3陶瓷离子有序度和微波介电性能的影响

利用常规固相法制备了Ba1-xZn1/3Nb2/303(x=O～0.02)陶瓷,研究了Ba缺位对Ba1-xZn1/3Nb2/3O3陶瓷的相成分、B位离子长程有序度(LRO)和微波介电性能的影响规律.X射线衍射(XRD)结果显示,适量的Ba缺位可以提高材料的阳离子有序度,x=0.01时陶瓷具有最大的阳离子有序度;Ba缺位...     

Preparation and characterization of Pb(Lu1/2Nb1/2)O3–Pb(In1/2Nb1/2)O3–PbTiO3 ternary ferroelectric ceramics with high phase transition temperatures

To explore new relaxor‐PbTiO₃ systems for high‐power and high‐temperature electromechanical applications, a ternary ferroelectric ceramic system of Pb(Lu_1/2Nb_1/2)O₃–Pb(In_1/2Nb_1/2)O₃–PbTiO₃ (PLN–PIN–PT) have been investigated. The phase structure, dielectric, piezoelectric, and ferroelectric properties of the as‐prepared PLN–PIN–PT ceramics near the morphotropic phase boundary (MPB) were characterized. A high rhombohedral‐tetragonal phase transition temperature T_R‐T of 165°C and a high Curie temperature T_C of 345°C, together with a good piezoelectric coefficient d₃₃ of 420 pC/N, were obtained in 0.38PLN–0.20PIN–0.42PT ceramics. Furthermore, for (0.8?x)PLN–0.2PIN–xPT ceramics, the temperature‐dependent piezoelectric coefficients, coercive fields and electric‐field‐induced strains were further studied. At 175°C, their coercive fields were found to be above 9.5 kV/cm, which is higher than that of PMN–PT and soft P5H ceramics at room temperature, indicating PLN–PIN–PT ceramics to be one of the promising candidates in piezoelectric applications under high‐driven fields. The results presented here could benefit the development of relaxor‐PbTiO₃ with enhanced phase transition temperatures and coercive fields.     

铌鲜酸铅弛豫型铁电陶瓷的介电老化行为研究

通过典型弛豫型铁电陶瓷铌镁酸铅介电老化行为的研究,发现高温区的Ｄｅｂｙｅ型弛豫过程与介电过程电老现象存在有机联系,指出复合钙钛矿弛豫型电体的结构缺陷特征对其介电老化起着重要作用,介电极化行为与老化行为对比分析和恒温经时老化研究表明,外的局域化电子和空穴对铁电微畴畴壁“钉扎”效应产生失电体介电化行为的快过程。     

低温烧结Mg4Nb2O9微波介质陶瓷

研究了V2O5对Mg4Nb2O9陶瓷的烧结温度、相结构和微波介电性能的影响.结果表明,添加1％～8％的V2O5,能使该陶瓷的烧结温度降低到1000～1050℃而对其微波介电性能的影响很小,材料的主晶相为有序型刚玉结构的Mg4 Nb2O9,存在Mg4Nb2O6和Mg5Nb4O15杂相而没有检测到V2O5的存在.陶瓷的密度对微波介电性能起着决定性作用,介电常数e1与密度成线性关系(在99.99％的置信限内,其相关系数为0.98252),Q·f值与密度的关系较复杂.添加1％的v2O5,将Mg4Nb2O9陶瓷的烧结温度降低到了1050℃,得到了εr=12.72,Q·f=151040GHz的优异性能.     

H3BO3对Li2Zn3Ti4O12微波介质陶瓷低温烧结与微波介电性能的影响

采用传统固相反应法制备了添加H3BO3助烧剂的Li2Zn3Ti4O12 (LZT)陶瓷,分别通过XRD、SEM、排水法及网络分析仪等方法研究了不同H3BO3添加量对所得陶瓷的物相、微观形貌、烧结特性与微波介电性能的影响.结果表明在LZT陶瓷中添加3wt% H3BO3可有效降低烧结温度,在900 ℃/2 h烧结条件下可以获得高致密性及优异的微波介电性:ρ=4.15 g/cm3,εr=17.916,Q×f=61200 GHz,Tf=-52.87×10-6/℃.     

BiFeO3-SrBi2Nb2O9陶瓷的介电与铁电性能研究

用传统的固相反应法制备了单相层状钙钛矿结构的xBiFeO3-(1-x)SrBi2Nb2O9(x=0、0.05、0.1)的铁电陶瓷,并对其电学性能进行了研究。研究结果表明BiFeO3的掺入降低了SBN的烧结温度,陶瓷晶粒尺寸减小,致密度提高;介电性能得到了改善,居里温度和在居里点的介电常数提高;铁电性能恶化,耐压特性下降。     

Properties of Low‐Temperature Sintering PNN–PMW–PSN–PZT Piezoelectric Ceramics with Ba(Cu1/2W1/2)O3 Sintering Aids

Piezoelectric ceramics Pb(Ni_1/3Nb_2/3)O₃–Pb(Mg_1/2W_1/2)O₃–Pb(Sb_1/2Nb_1/2)O₃–Pb(Zr_0.39Ti_0.61)O₃ with Ba(Cu_1/2W_1/2)O₃ sintering aids were fabricated using economical industrial oxide powders and their piezoelectric, dielectric, and ferroelectric properties were investigated in order to develop low‐temperature sintering ceramics for multilayer piezoelectric actuators. A quadratic formula and the Curie–Weiss law reveal that the ceramics are typical displacive‐type ferroelectric relaxors. The ceramics sintered as low as 900°C have good piezoelectric properties of d₃₃ = 551 pC/N, k_p = 0.52, ε_r = 3583, tgδ = 0.02, and T_C = 161°C, which is much promising to manufacture multilayer piezoelectric transducers.     

前驱体制备(1-x)CaTiO3-xCa(Zn1/3Nb2/3)O3陶瓷的微波介电性能

以ZnNb2O6为前驱体,通过固相反应合成了(1-x)CaTiO_3-xCa(Zn_(1/3)Nb_(2/3))O_3体系微波介质陶瓷。对固溶体进行了结构与性能测试,研究了体系结构与性能随组份变化规律。结果表明,由于Zn,Nb对Ti的B位取代增大了B-O八面体的倾斜角,从而导致随着Ca(Zn_(1/3)Nb_(2/3))O_3含量从0.2增加至0.8,介电常数从109减小为49,Q×f值从8340GHz增至13200GHz,频率温度稳定系数由321ppm/℃降为-18ppm/℃。在x=0.7时获得ε_1≈56,Q×f≈11500GHz,τ_f≈-5ppm/℃的最佳性能。     

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/℃。     

锑替代铋对铋锌铌陶瓷介电性能的影响

研究了Sb3＋替代Bi3＋对Bi2O3-ZnO-Nb2O5（BZN）系介质材料结构和性能的影响,并借助X射线、扫描电镜、LCR4284测试仪对其相结构和介电性能进行分析。研究结果表明,经Sb3＋替代的BZN陶瓷样品成瓷温度仍为1 000℃;随着Sb3＋替代量的增加,Bi2O3-ZnO-Nb2O5系介质材料的晶粒尺寸、介电常数、介电损耗都有所变化。当替代量x=0.4时,介电性能最佳,介电常数为184,介电损耗为0.001。     

ZrO2/Al2O3复相陶瓷的制备及性能研究

本文以工业用ZrO2和α-Al2O3微粉为原料,通过干压成型和常压烧结工艺制备ZrO2/Al2O3复相陶瓷.通过检测复相陶瓷的体积密度、显气孔率、常温抗折强度、烧后线变化率和热震稳定性,研究不同α-Al2O3微粉加入量及添加剂Y2O3对ZrO2/Al2O3复相陶瓷烧结性能、常温强度、热震稳定性及微观结构的影响,并通过SEM方法对烧后试样的微观结构进行表征.结果表明:系统配料中加入Al2O3会降低ZrO2/Al2O3复相陶瓷的致密度,常温强度随着Al2O3加入量增大而呈现先增大后减小趋势,然而热震稳定性有一定程度改善.Y2O3作为一种助烧剂可以促进ZrO2/Al2O3复相陶瓷结构内晶粒长大,加入Y2O3有利于增强复相陶瓷的烧结性.     

V2O5掺杂对(Bi1.5Zn1.0Nb1.5)O7介质陶瓷性能的影响

采用传统的固相反应法制备陶瓷试样,借助XRD,SEM和LCR测试仪,研究了V2O5掺杂对(Bi1.5Zn1.0Nb1.5)O7介质陶瓷的烧结特性和介电性能的影响.结果表明,掺杂适量V2O5后试样的烧结温度明显降低,相结构仍为立方焦绿石单相,且具有良好的介电性能:介电常数(εr)为135～154,介电损耗(tan δ)为0.0033～0.0007,频率温度系数(τf)为-442～-387(2MHz).     

Structural and electrical properties of lead free ceramic: Ba(La1/2Nb1/2)O3

Abstract

Abstract

Lead free perovskite Ba(La_1/2Nb_1/2)O₃ was prepared by conventional ceramic fabrication technique at 1375°C for 7?h in air atmosphere. The crystal symmetry, space group and unit cell dimensions were estimated using Rietveld analysis. X-ray diffraction analysis indicated the formation of a single phase monoclinic structure with space group P2/m. Energy dispersive X-ray analysis and scanning electron microscopy studies were carried to study the quality and purity of the compound. Permittivity data showed low temperature coefficient of capacitance (T _CC = 11%) up to 100°C. The circuit model fittings were carried out using the impedance data to find the correlation between the response of real system and idealised model electrical circuit. Complex impedance analyses suggested the dielectric relaxation to be of non-Debye type. The correlated barrier hopping model was employed to successfully explain the mechanism of charge transport in Ba(La_1/2Nb_1/2)O₃. The AC conductivity data were used to evaluate the density of states at Fermi level, minimum hopping length and apparent activation energy.     

CaO-B2O3-SiO2系微晶玻璃的低温烧结机理

研究了CaO-B2O3-SiO2系微晶玻璃的烧结过程、析晶机制、微观结构以及介电性能等。该材料能够在850℃的低温烧结，烧结体具有良好的介电性能（er=4.975,tgδ≤0.001,1GHz)。微观结构主要为75％－80％体积百分比的晶相（晶粒尺寸为50－100nm)，少量的残余玻璃相和气孔；主要晶相为CB（CaO.B2O3),C6S4(6CaO.4SiO2)和CS（CaO.SiO2)。该材料适用于高频电子元器件等领域。     

Bi2O3及MnO2掺杂对[(Pb,Ca) La](Fe,Nb)O3介质陶瓷结构及微波性能的影响

研究了Bi2O3及MnO2掺杂量对[(Pb0.5Ca0.5)0.92La0.08](Fe0.5Nb0.5)O3陶瓷结构及介电性能的影响.结果表明Bi2O3及MnO2均是良好的烧结助剂,可降低体系的烧结温度60～100 ℃,同时提高陶瓷的密度.XRD图谱证明当MnO2的质量分数≤2%时,陶瓷为钙钛矿相及焦绿石相,表明Mn4+进入主相晶格,而Bi2O3的掺杂会使体系中出现未知第三相.随MnO2的增加,陶瓷的介电常数先增加后减小,同时使品质因数及谐振频率温度系数的单调下降.Bi2O3的掺杂则会使陶瓷介电常数及谐振频率温度系数升高,而品质因数下降.Bi2O3及MnO2的联合掺杂比单一掺杂更有效地降低了陶瓷的烧结温度,达100～140 ℃,且在低温烧结条件下有比单一掺杂时更好的微波介电性能.其中当Bi2O3和MnO2的质量比k=1,2种添加物总质量分数w=1%,烧结条件为1 050 ℃,保温4 h,陶瓷的相对介电常数εr,品质因数(Q)与谐振频率(f)的乘积Qf以及谐振频率温度系数分别为91.1, 4 870 GHz和18.5×10-6/℃.     

MnO2掺杂对[(Pb,Ca)La](Fe,Nb)O3介质陶瓷结构及微波性能的影响

摘要:研究了MnO2 掺杂量对[(Pb0.5Ca0.5)0.92La0.08](Fe0.5Nb0.5)O3 陶瓷结构及介电性能的影响。研究表明MnO2 是良 好的烧结助剂，可降低体系的烧结温度60 ～1 0 0℃，同时提高陶瓷体密度。X R D 图谱证明当M n O2 的质量分数≤ 2% 时，陶瓷为钙钛矿相及焦绿石相，表明M n 4 进入主相晶格。随M n O2 的增加体系介电常数先增加后减小，同 时造成品质因数及谐振频率温度系数的单调下降。     

低温烧结95瓷研究及其生产

采用廉价添加物,使95瓷的烧结温度最低可降到1430℃。它的各项性能优于国家标准GB5593-96中的A95的指标。已在湖南、浙江和江苏等省的多家工厂推广生产,取得良好的经济效益。