直流偏压对PMZNT弛豫铁电陶瓷介电性能的影响

对PMN－PZN－PT系弛豫铁电陶瓷的直流偏压特性进行了研究,直流偏压使介电常数的最大值εmax下降,介电常数最大值对应的温度Tmax升高,频率色散受到压抑．同时使介温曲线变得平坦．应用冻结偶极子、慢偶极子的概念,对实验结果进行了分析．     

交流测试电场对PMZNT弛豫铁电陶瓷介电性能的影响

考察了不同交流测试电场对ＰＭＮ－ＰＺＮ－ＰＴ系弛豫铁电陶瓷介电性能的影响。测试结果表明，交流测试电场的增大导致介电常数最大值对应的温度Ｔｍａｘ下降，同时介电常数在Ｔｍａｘ附近及低于Ｔｍａｘ温度以下增大。并应用冻结偶极子、慢偶极子的概念对实验结果进行了定性分析。     

PMN和PZN基复相陶瓷的制备及其介电温度稳定性的研究

以PZN基和PMN基粉本为起始组元，采用两相混合烧结法成功的制备了两相共存的复相陶瓷，介电性能测试表明，复相陶瓷的室温介电常数为5377（1kHz)，其介质电温谱在－15℃－＋90℃温度范围内相当平坦，介电温度稳定性大幅提高，据键价理讨论了复相陶瓷的设计和组成控制，并初步探讨了复相陶瓷提高介电温度稳定性的机制。     

掺钛铌镁酸铅铁电体的自发和场诱导相变

测试了掺钛铌镁酸铅系列铁电陶瓷介电和热释电温度梯,观察到自发和场诱导正常铁电体－驰豫型铁电体－顺电体相互转变的现象,在分析这一相变的特点和相应结构特征的基础上,提出了驰豫型铁电体钠米极性微区的动态结构模模型。     

PMN－PT陶瓷材料的微观结构、介电性能及电致伸缩效应的研究

本文研究了ＰＭＮ－ＰＴ陶瓷材料微观结构上Ｂ位离子的有序－无序排列情况与宏观的介电性能、相变弥散及电致伸缩效应的联系．ＰＭＮ－ＰＴ介电常数很高，在室温附近发生弥散相变，电致伸缩效应显著，形变量达１×１０－３．采用退火处理的方法，可提高ＰＭＮ－ＰＴ的Ｂ位有序度，展宽弥散相变温区，改善材料的热稳定性和滞后现象．     

前驱体制备途径对PFN-PMN二元铅基铁电陶瓷性能的影响

综合运用 ＸＲＤ、ＳＥＭ、ＴＥＭ、ＥＤＳ和介电测量等方法,考察了一步预煅烧法和二步预煅烧法等前驱体制备途径对Ｐｂ（Ｆｅ_１／２Ｎｂ_１／２）Ｏ_３（ＰＦＮ）－Ｐｂ（Ｍｇ_１／３Ｎｂ_２／３）Ｏ_３（ＰＭＮ）二元系铁电陶瓷显微结构和介电性能的影响．研究结果表明,对（１－Ｘ）ＰＦＮ－ＸＰＭＮ二元系而言,在所考查的组成范围内（Ｘ＝０～０.５）;其居里温度与ＰＭＮ的含量近似成线性关系,且随Ｘ的增加,居里温度向低温方向移动.峰值介电常数随Ｘ的增加而降低．（预）煅烧和烧结条件对显微结构和介电性能都有不可忽视的影响．对用一步预煅烧法和二步预煅烧法得到的样品的介电性能和其他性能进行了比较,并对其差异产生的可能机制进行了讨论．     

改性PLZT陶瓷偏压压电效应的研究

本文讨论了铌和钡改性的PLZT10/65/35铁电陶瓷的横向场诱应变X2,不同温度及偏压下的介电常数K33,平面机电耦合系数kp和弹性柔顺系数SE11,并计算了等效压电常数d31。铌和钡改性的PLZT铁电陶瓷在15kV/cm的电场下横向应变分别为-51×10-4和-4.5×10-4。实验表明它们的k。和d31值可由直流偏压控制,室温下k。的饱和值分别为0.53和0.52,｜d31｜的最大值分别为230pC/N和225pC/N,且压电常数的温度系数都比PMN-PT系陶瓷小得多。     

铌酸镁的合成与铌镁酸铅基电致伸缩陶瓷性能关系研究

研究了不同温度MgNb2O6的原始合成反应,结果显示游离MgO的含量随MgNb2O6合成温度的升高而减少．首先合成MgNb2O6,但合成时并不加入过量MgO,合成温度为1050℃,由此制备了一种PMN基电致伸缩陶瓷．在X射线衍射检测极限内,并未发现此PMN基电致伸缩陶瓷存在焦绿石第二相．对该陶瓷施加1kV／mm频率为0．07Hz的准静态电场,在室温下其纵向电致应变（S11）达1．05×10－3而滞后仅为6．8％．还研究了MgNb2O6的合成温度与PMN基陶瓷电致伸缩性能的关系,它表明PMN基陶瓷的居里温度Tc随MgNb2O6的合成温度的提高而增高,从而引起介电常数的下降和滞后增大．     

PBLZT弛豫铁电陶瓷的动态及偏压介电和压电特性

测量了３ｍｏｌ％Ｂａ掺杂的ＰＬＺＴ１０／６５／３５弛豫铁电陶瓷的电滞回线、横向场诱应变、偏压下的介电常数和压电常数,并根据电滞回线和场诱应变曲线的斜率计算了动态介电常数和压电常数．实验表明,电场＜８ｋＶ／ｃｍ时,动态介电常数比偏压介电常数大很多,电场＞８ｋＶ／ｃｍ时,差值随电场增大而减小;电场在３～１５ｋＶ／ｃｍ之间时,动态压电常数比偏压压电常数大很多,电场＜３ｋＶ／ｃｍ及＞１５ｋＶ／ｃｍ时,动态压电常数和偏压压电常数相差不大．     

复相弛豫铁电陶瓷的相组成与介电性能

采用两相混合烧结法在Ｐｂ（Ｚｎ１／３Ｎｂ２／３）Ｏ３－ＢａＴｉＯ３－ＰｂＴｉＯ３系统中制备了弛豫铁电陶瓷材料，相组成研究表明，该陶瓷具有两相共存的复相结构，对复相陶瓷的介电性能进行了研究，结果表明，复相结构可有效地改善弛豫铁电陶瓷的介温特性、频率特性和介质老化性能。     

DC field dependence of dielectric constant and loss factor of Al2O3-doped barium strontium titanate for application in phased array antennas

DC electric field effects on the real part of the relative dielectric constant and the loss factor of barium strontium titanate for application in phased array antennas have been studied. The real part of the relative dielectric constant of the specimens decreases with increasing applied DC field. The loss factor under bias DC electric field is slighter than the real part of the relative dielectric constant does. The tunability is about 24% for barium strontium titanate doped with 1 wt% Al₂O₃ content. Variation of fitted phenomenological coefficients with Al₂O₃ contents below 10 wt% is small and a rapid increase of the fitted phenomenological coefficient occurs above 10 wt%. Variation of field coefficient A and tunability with Al₂O₃ contents has the same trend as that of the grain size. The real part of the relative dielectric constant of Al₂O₃ doped barium strontium titanate decreases rapidly before 1.0 KV/cm and slowly after 1 KV/cm compare to the data obtained by the curve fitting. There is a conduction loss mechanism other than the intrinsic dielectric loss for the dielectric loss under bias electric field.     

铌酸钠钾基压电陶瓷的电场诱导介电特性

采用传统的固相反应合成法制备了0.9(K0.5Na0.5)NbO3-0.1LiSbO3(KNN-LS)无铅压电陶瓷,研究了它在不同直流偏置电场下的介电常数的频谱,并分析了直流偏置电场诱导下的相对介电常数变化值Δrε和调谐率K.随着偏置电场的增大,Δrε和K都变大,这与传统的钛酸锶钡陶瓷类的材料结果相反.同时,随着频率的增加,Δrε和K都减小.Δrε随偏置电压的增加而增大,意味着在高的电压下,样品的色散效应增大,其原因可以用空间电荷的极化理论来解释.另外,在外加偏置电压不高的情况下(3 kV/cm),就可以获得相对较大的调谐率1.17%.     

贱金属电极MLCC用低失真介质陶瓷材料

在还原气氛下,烧制出一种主晶相为(Ba,Ca,Sr,)(Zr,Ti)O3介质陶瓷材料. XRD 相成分分析发现:合理的工艺方法可获得不含强铁电相的介质材料.该介质材料具有较高的介电系数(ε_r为300-400),较低介质损耗(tgδ≤30×10^-4),直流偏压下电容量变化小(偏压为2.5kV/mm时变化约0.03%),且介电系数温度特性符合EIA标准之X7R特性的要求等特点, 适用于制作低失真贱金属电极MLCC.     

Performance of capacitors under DC bias at liquid nitrogen temperature

Several commercially available capacitors were evaluated at the liquid nitrogen temperature (77 K). Our primary interest was their performance under a bias voltage when used as DC link capacitors in cryogenic power electronics. In general, the performance of polymer capacitors and certain ceramic capacitors is almost independent of the temperature, DC bias, and frequency. On the other hand, ceramic capacitors based on high dielectric constant materials showed a strong dependence on the boundary conditions. Aluminum electrolytic capacitors showed a dramatic decrease of capacitance at 77 K, possibly due to the electrolyte being frozen and therefore losing its conductivity.     

Effect of lattice-mismatch strain on the structural and dielectric properties of (Pb,Sr)TiO3 thin films grown by pulsed laser deposition

Pb_0.35Sr_0.65TiO₃ (PST) thin films have been fabricated on LaAlO₃ (LAO) and MgO substrates using the pulsed laser deposition technique. The microstructure characteristics of the films were examined by means of X-ray diffraction, atomic force microscopy, scanning electron microscopy and Raman spectroscopy, and the results indicate that the films are epitaxially grown and show good crystallinity. The dielectric constant dependence on DC bias voltage and temperature were measured in a planar capacitor configuration for these films. Compared to the PST thin film grown on LAO, the film grown on MgO showed a higher temperature of the capacitance maximum and a higher dielectric constant at zero bias. We explain the results by taking into account the lattice-mismatch strain between the substrate and the film. In contrast to the in-plane compressive strain induced by the LAO substrate, the in-plane tensile strain induced by the MgO substrate enlarges the unit cell of PST and enhances the magnitude of dipole moments, which increases the dielectric constant. These results indicate that a reasonable in-plane tensile strain could improve the dielectric properties of PST thin films.     

铌、钽电容器性能分析

钽铌属于同族元素 都是阀金属材料,其介电常数分别为27、41,都可以用来制作电解电容器。本文使用铌和钽2种材料分别制作电解电容器,并通过容量损耗测试仪、漏电流测试仪、电子扫描电镜等分析仪器对其和始性能、偏压性能、温度特性、寿命特性及其电介质层的微观特性进行检测分析。结果表明使用铌材料同样可以得到性能较好的电解电容器。     

Direct-current field dependence of dielectric properties in B2O3-SiO2 glass doped Ba0.6Sr0.4TiO3 ceramics

The Ba_0.6Sr_0.4TiO₃ ceramics doped B₂O₃-SiO₂ glass prepared by a sol-gel process and the effect of glass content on the DC field dependence of dielectric characteristics in Ba_0.6Sr_0.4TiO₃ ceramics were studied. The samples were observed and analysed by SEM and X-ray diffraction. The dielectric constant of a BST sample with 1 mol% B₂O₃-SiO₂ sintered at 1250°C was as good as that of undoped BST sintered at 1340°C. The dielectric constant samples decreases as the applied DC field increases. The influence of the DC field on the loss factor is much less than that on the dielectric constant. With increasing of the applied voltage, the T _c was increased and the peaks were surpressed and broadened. With increasing of glass content, the peaks were also surpressed and broadened. The maximum dielectric constant and the percentage change of dielectric constant under a DC field increase.     

复合钙钛矿铁电陶瓷的电场诱导畴反转特征研究

本文通过铌锌酸铅基复合钙钛矿结构铁电陶瓷的电畴观察、强场极化反转行为以及直流偏压下介电行为和X射线衍射峰等的详细测量,对铁电微畴、宏畴在外场诱导下的反转规律进行了分析,探讨了与铁电陶瓷介电行为相对应的微观极化机制。