溶胶-凝胶法制备(Ba0.85Ca0.15)(Ti0.9Zr0.1)O3无铅压电陶瓷研究

锆钛酸钡钙基无铅压电陶瓷由于具有较好的压铁电性能且环境友好而备受研究者关注,但其存在烧结温度高(>1450℃)、居里温度低等缺点。为降低锆钛酸钡钙基压电陶瓷的预烧及烧结温度,并优化其电学性能,本研究采用溶胶-凝胶法成功合成了(Ba_0.85Ca_0.15)(Ti_0.9Zr_0.1)O₃无铅压电陶瓷的前驱粉体,并在预烧温度为1000℃、烧结温度为1420℃时成功制备了(Ba_0.85Ca_0.15)(Ti_0.9Zr_0.1)O₃陶瓷,相较于传统固相法,陶瓷的预烧温度降低了250℃,烧结温度降低了30℃,成功改善了陶瓷的烧结行为,得到了铁电性能、介电性能和压电性能优良且致密性良好的低温烧结陶瓷。     

镨气相扩渗PbTiO3陶瓷的制备及其电性能

采用气相化学热扩渗方法制备了Pr改性的PbTiO3陶瓷,并对扩渗后PbTiO3陶瓷的组成、结构及电性能的变化进行了研究。通过XRD,SEM及Pr元素的面扫描分析证实Pr元素已经渗入到PbTiO3陶瓷体相,且分布均匀,并生成了Pr2Ti2O7等新的化合物,由此导致了PbTiO3陶瓷导电性的显著增强。在Pr扩渗PbTiO3陶瓷的实验中,通过正交试验法确定了扩渗的最佳工艺条件,即Pr元素的扩渗质量分数为0.015,扩渗时间为3 h,扩渗温度为860℃,此时PbTiO3陶瓷的导电性最好,其室温电阻率从2.0×1010下降为9.487Ω·m。对改性的PbTiO3陶瓷进行了交流复阻抗分析,随着温度的升高,扩渗后的PbTiO3陶瓷的导电性更强,其晶粒电阻和晶界电阻均随温度升高而呈逐渐下降的趋势,已不存在PTC效应,有向导电体过渡趋势。     

WO3-B2O3复合掺杂钛酸锌陶瓷的低温烧结和相转变

采用传统氧化物混合法结合半化学工艺制备了钛酸锌陶瓷，研究了WO₃-B₂O₃复合掺杂对陶瓷低温烧结行为、低烧机制和相转变的影响。研究结果表明：WO₃-B₂O₃掺杂将陶瓷烧结温度从1 100 ℃降至900 ℃；WO₃和B₂O₃的降温机制不同，前者主要是固相反应烧结机制，而后者应为液相烧结机制；WO₃促进了六方相ZnTiO₃的分解，对其原因进行了探讨；测试了不同频段下试样的介电性能，发现不同频段下，极化机制不同。     

锆钛酸铅(PZT)陶瓷的应用与发展

一、引言 锆钛酸铅压电陶瓷于1955年由美国的B.Jaffe等人发现之后,由于它具有机械耦合系数高、温度特性好、居里温度高(～300℃)等优点,大大推进了压电陶瓷的实用化。用Sr、Ca、Mg等元素取代Pb或添加Nb、La、Sb、Cr、Mn、Fe、Co、Ni等元素进行改性,可以得到许多不同用途的 PZT系压电陶瓷,如PZT-4,PZT-5,PZT-6,PZT-7及PZT-8等,利用它们各自不同的效应可以应用在不同的方面。     

稀土改性钛酸铅微粉的水热合成及其性能研究

用水热法合成了几种稀土（Ｌａ，Ｐｒ，Ｎｄ，Ｓｍ，Ｅｕ）和锰掺杂改性的钛酸铅（ＰｂＴｉＯ３，简称ＰＴ）陶瓷微粉，研究了掺Ｌａ和Ｍｎ的ＰＴ固溶体的四方（铁电）相与立方（顺电）相之间的相变，掺杂Ｌａ（ｘ（Ｌａ）＝０．０４）和Ｍｎ（ｙ（Ｍｎ）＝０．０１）的ＰＴ固溶体的居里温度大约为４００℃，测定了稀土掺杂量（ｘ＝０．０４～０．０８）与其压电性能之间的关系，随Ｌａ掺杂量的增加，ＰＴ固溶体的ｄ３３增大，ｇ３３     

添加稀土和重金属氧化物玻璃陶瓷的制备和烧结及性能研究

通过分别添加稀土氧化物和重金属氧化物作为烧结助剂 ,采用电子陶瓷工艺制备了具有非化学计量组成的堇青石基玻璃陶瓷。为了评价玻璃粉末的烧结特性 ,对烧结热处理后试样的密度和显气孔率进行了测定。结果表明 ,两种烧结助剂能促进玻璃的烧结致密化和降低 μ 堇青石向α 堇青石转变的温度并影响玻璃陶瓷的介电性能。玻璃陶瓷的完全致密化温度可以低到 90 0℃。该材料具有低的介电常数 (≈ 5 )和低的介质损耗因子 (≤ 0 2 % )以及合适的热膨胀系数 ((2 80～ 3 5 2 )× 10 - 6 ℃ - 1) ,能够在低于 95 0℃与高导电率的金属如金、铜和银 /钯共烧 ,是一种潜在的低温共烧陶瓷基板材料。     

掺杂Sm_2O_3的Y_2O_3-2TiO_2系微波介质陶瓷的性能研究

以具有中介电常数的新型Y2O3-2TiO2系微波介质陶瓷为基体,选用Sm2O3作为掺杂改性剂,通过传统固相法制备成陶瓷。重点研究了不同Sm2O3掺杂量对基体Y2O3-2TiO2微波介质陶瓷物相组成和介电性能的影响。采用X射线衍射和扫描电子显微镜分别对其物相组成和显微结构进行了分析,用阻抗分析仪和网络分析仪测试其介电性能。结果表明:掺杂Sm2O3未改变材料的主晶相,仍为A2B2O7烧绿石结构,Sm3+取代Y3+占据A位;掺杂有效降低了陶瓷的烧结温度,掺杂量为5%(质量分数)时,烧结温度为1330℃,材料的综合性能最佳,εr=23,tanδ=0.0046,Q×f=6713 GHz。     

施主掺杂微量的Y_2O_3对BaTiO_3基样品的电性能及PTC效应的影响

为了适应市场对过热保护作用的PTC热敏陶瓷应用需求,采用了固相法的烧结工艺来制备PTC热敏陶瓷样品。主要研究了施主掺杂微量Y_2O_3的BaTiO_3基陶瓷在空气中1 340~1 360℃烧结0.5~1 h后其室温电阻率与升阻比(ρ_(max)/ρ_(min))随施主掺杂含量的变化关系。在实验中我们详细地阐述了BYT陶瓷样品的室温电阻率随施主掺杂含量(0.1≤x≤0.3 mol%)的变化曲线呈现类似"U"形曲线的半导化机理;根据Heywang-Jonker模型成功地解释了该样品的PTC效应随施主掺杂量的增加而呈现出先增加后减小的变化趋势的原因;讨论了烧结助剂SiO_2对BYT样品微观结构以及电性能的影响。     

通过微观形貌对Ba(Ti,Sn)O_3压电陶瓷的结构及压电性能分析

本文采用传统固相合成法制备了(Ba_(1-x)Ca_x)(Ti_(0.98)Sn_(0.02))O_3(BCTS,x=0.00、0.01、0.02、0.03)无铅压电陶瓷,研究了不同烧结温度下Ba(Ti,Sn)O_3压电陶瓷材料的微观形貌对相结构及压电性能的影响。X-射线衍射(XRD)分析表明,所有陶瓷样品均为单一、纯钙钛矿结构,无第二相生成。通过扫描电子显微镜(SEM)图片可知,陶瓷样品在烧结温度为1450℃时,晶粒更加均匀、陶瓷结构更加致密,气孔较少并且晶粒成螺旋状结构生长。当陶瓷烧结温度为1450℃,并且x=0.01时,陶瓷的综合性能达到最佳,其压电常数(d33)达到346pC/N。     

CaTiO3∶Zn溶胶-凝胶法制备、结构及介电性能

采用溶胶-凝胶法制备了CaTiO3∶Zn纳米粒子,透射电镜图显示平均粒径为25 nm。Zn的掺杂位置对于陶瓷相组成和烧结特性有很大影响。Ca1-xZnxTiO3和CaTiO3+zZnO样品的Zn以Zn2TiO4相形式存在;而CaZnyTi1-yO3-δ(y=0.01)样品中的Zn进入Ti位形成固溶体,无明显的降温效果,当Zn量增至0.05和0.1时,出现ZnO相。ZnO和Zn2TiO4第二相的存在均能明显促进陶瓷烧结。CaTiO3∶Zn超细粉体可在较低温度下致密烧结(≤1 250℃)。1 250℃烧结的CaZnyTi1-yO3-δ(y=0.01)陶瓷具有较好的介电性能:介电常数ε=157,品质因数Q×f=6 819 GHz,谐振频率温度系数τf=7.51×10-4℃-1。     

溶胶-凝胶法制备掺锰钛酸钡纳米粉体及其陶瓷

The Mn-doped barium titanate nanosized powders and ceramics were prepared via the sol-gel process. The powders and ceramics were characterized by XRD， SEM and TEM. The dielectric properties of the ceramics were also measured. The influences of calcination temperature and Mn concentration on the microstructure， dielectric properties and phase composition of BaTiO₃ nano-powders and ceramics were discussed. The results indicated that the BaTiO₃-based powders doped with 1.0mol% Mn were mainly in cubic BaTiO₃ phase， but the tetragonal phase became more evident when the calcination temperature increased. After sintering， Mn-doped ceramics were mainly composed of cubic BaTiO₃. Specially， a new phase of hexagonal crystal BaTiO₃ and BaMnO₃ existed in the ceramics doped with 5.0mol% Mn and the ceramic grains were in ‘clintheriform’. The structure of ‘clintheriform’ led to the poor densification of ceramics， reducing the dielectric constant obviously. The dielectric constants of BaTiO₃ ceramics first increased and then decreased as the Mn concentration increased. The room temperature dielectric constant was 2 290 and the lowest dielectric loss was 0.004 when the Mn concentration was 0.5mol%.     

AgNbO<Subscript>3</Subscript> ceramics synthesized by aqueous solution-gel method

AgNbO₃ powders and ceramics were prepared by aqueous solution-gel method. The phase evolution of the powders was investigated by TG/DSC and XRD. The results showed that the pure AgNbO₃ phase was obtained at 600 °C without special treatment. The sintering behavior and dielectric properties of the AgNbO₃ ceramics were also investigated. It showed the dense ceramics were obtained as lower as 925 °C, which had the excellent dielectric properties with the permittivity of 291 and dielectric loss of about 1.7% at 1 MHz. The coarse grains were observed for the sample sintered over 975 °C, and then they decreased with the sintering temperature further increasing to 1,050 °C.     

Nd-doped barium titanate ceramics with various Ti/Ba ratios prepared by sol-gel method

The Nd-doped BaTiO3 nanocrystalline powders and ceramics with different Ti/Ba ratios were prepared by sol-gel method. Phases and microstructures of the Nd-doped BaTiO3 based powders and ceramics were characterized by XRD, SEM and TEM methods. The results revealed that the powders synthesized by sol-gel method were nanometer scale (30-60 nm) and were mainly composed of cubic BaTiO3 with a small amount of BaCO3. After sintering at high temperature, both cubic BaTiO3 and BaCO3 were transformed into tetrahedron BaTiO3 phase. The dielectric properties of the ceramics were also determined and the influence of Ti/Ba ratio on the dielectric properties was discussed. The Tc did not change with the variation of Ti/Ba ratio, while theεmax increased firstly and then decreased. The excess TiO2 is benefit for the modification of ceramics' microstructure and dielectric properties.     

室温固态反应制备纳米Ba1－xSrxTiO3固溶体及其结构与介电性能研究

采用室温固态反应合成了一系列Ba_1－xSr_xTiO₃固溶体纳米粉末(0≤x≤1.0). 经XRD物相分析和d-间距-组成图证明, 产品为立方晶系的完全互溶取代固溶体. TEM形貌观察, 粒子基本为球形, 平均粒径40 nm. 该方法具有产率高, 无需溶剂, 对环境无污染等优点. 通过制陶实验, 分别测定了该系列固溶体的室温介电常数、介电损失以及介电常数随温度的变化. 结果发现, 采用室温固态反应在BaTiO₃中掺入适量锶, 由于掺杂离子均匀进入母体晶格, 引起居里点降低, 室温介电常数达11000以上, 介电损耗由BaTiO₃纯相的0.03 (3%)降为0.008 (0.8%). 纳米粉体的烧结温度为1180 ℃, 比传统微米级粉体的烧结温度降低100～150 ℃.     

(K_(0.485)Na_(0.485)Li_(0.03))NbO_3-Pb(Zr_(0.53)Ti_(0.47))O_3陶瓷的介电铁电性能

采用传统电子陶瓷工艺制备新型钙钛矿体系(1-x)(K_(0.485)Na_(0.485)Li_(0.03))NbO_3-Pb(Zr_(0.53)Ti_(0.47))O_3陶瓷,研究了该体系陶瓷的介电铁电性能.X射线衍射分析表明:所有陶瓷样品都具有单一的钙钛矿结构,在0.65≤x≤0.75时,出现明显的正交相和四方相的准同型相界区.测试结果表明:陶瓷具有高介电常数.低介质损耗,良好的温度稳定性;获得了饱和的电滞回线,显示了优良的铁电性能.尤其在x=0.75时各项性能达到最佳,其中介电常数ε_r=1590,介电损耗tan δ=0.017,居里温度T_c=295℃,剩余极化强度P,=28.6 μC·cm~(-1),矫顽场强E_c=0.89 kV·mm~(-1).     

Nd-doped barium titanate ceramics with various Ti/Ba ratios prepared by sol-gel method

The Nd-doped BaTiO₃ nanocrystalline powders and ceramics with different Ti/Ba ratios were prepared by sol-gel method. Phases and microstructures of the Nd-doped BaTiO₃ based powders and ceramics were characterized by XRD, SEM and TEM methods. The results revealed that the powders synthesized by sol-gel method were nanometer scale (30 – 60 nm) and were mainly composed of cubic BaTiO₃ with a small amount of BaCO₃. After sintering at high temperature, both cubic BaTiO₃ and BaCO₃ were transformed into tetrahedron BaTiO₃ phase. The dielectric properties of the ceramics were also determined and the influence of Ti/Ba ratio on the dielectric properties was discussed. The T_c did not change with the variation of Ti/Ba ratio, while the ?_max increased firstly and then decreased. The excess TiO₂ is benefit for the modification of ceramics’ microstructure and dielectric properties.     

锰掺杂Ba0.6Sr0．4TiO3-MgTiO3复相陶瓷的制备和介电性能

以分析纯的Ba(NO3)2、Sr(NO3)2、草酸和钛酸丁酯为原料,采用草酸盐共沉淀法制备了钛酸锶钡(Ba0.6Sr0.4tiO3,BST)纳米粉体.XRD和SEM分析结果表明,该方法制备出立方相的Ba0.6Sr0.4TiO3粉体,平均粒径小于100 nm,具有较高的烧结活性.用传统固相法制备了锰掺杂钛酸锶钡.钛酸镁(Ba0.6Sr0.4TiO3-MgTiO3,BST-MT)复相陶瓷,系统研究了掺杂0.1%-2.0%(x,摩尔分数,下同)锰对钛酸锶钡-钛酸镁复相陶瓷微观形貌和介电性能的影响机理.结果表明,当锰的掺杂量小于1.5%时,Mn作为受主掺杂取代占据钙钛矿ABO3的B位,因此导致居里点略微向高温偏移和相变扩散的发生,锰的掺杂导致晶格畸变,促进了晶粒生长,使晶界相比例下降,因此介电损耗随着锰掺杂量的增大而减小;当锰的掺杂量为1.5%时,介电损耗达到最小值,继续增大掺杂量,介电常数下降,介电损耗上升.     

Bi1.5ZnNb1.5O7 cubic pyrochlore ceramics prepared by aqueous solution–gel method

Bi_1.5ZnNb_1.5O₇ cubic pyrochlore ceramic was successfully prepared by the aqueous solution method. The preparation, microstructure development and dielectric properties of ceramics were investigated. Homogeneous precalcined ceramics powders have a cubic pyrochlore phase after thermal treatment at the temperature as low as 450 °C. The aqueous solution–gel method, which Bi, Zn and Nb ions are chelated to form metal complexes, leading to the formation of cubic pyrochlore phase at low firing temperatures. No detectable intermediary phase such as BiNbO₄ or pseudo-orthorhombic pyrochlore is observed in the XRD patterns of ceramics at the sintering temperature range from 850 to 1,000 °C. The dielectric properties study revealed that the ceramics sintered at 900 °C show excellent performance with dielectric constant of 111 and dielectric loss of 2.3871 × 10⁻⁴ under 1 MHz at room temperature.     

Improved dielectric properties of BaxSr1−xTiO3-based composite ceramics derived from core–shell structured nanopowders

We performed a study on the dielectric properties of Ba_xSr_1−xTiO₃–Mg_0.9Zn_0.1O (BST–MZO) composite ceramics derived from core–shell structured nanopowders with the shell of zinc doped MgO and core of Ba_xSr_1−xTiO₃. It was found that the ceramics exhibit a significant improvement in dielectric response under a DC electric field. The Curie temperature decreases more significantly in the BST–MZO composite ceramics compared to that of pure BST ceramics. The tunability of Ba_0.75Sr_0.25TiO₃–40%MZO is 23.49% at 20 °C. The dielectric properties at high frequency also show low dielectric constant and great reduction in dielectric loss. These ceramics are expected to be useful in microwave devices.     

锰掺杂Ba0.6Sr0.4TiO3-MgTiO3复相陶瓷的制备和介电性能

以分析纯的Ba(NO3)2、Sr(NO3)2、草酸和钛酸丁酯为原料, 采用草酸盐共沉淀法制备了钛酸锶钡（Ba0.6Sr0.4TiO3, BST）纳米粉体. XRD和SEM分析结果表明, 该方法制备出立方相的Ba0.6Sr0.4TiO3粉体, 平均粒径小于100 nm, 具有较高的烧结活性. 用传统固相法制备了锰掺杂钛酸锶钡-钛酸镁(Ba0.6Sr0.4TiO3-MgTiO3, BST-MT)复相陶瓷, 系统研究了掺杂0.1%-2.0%(x, 摩尔分数, 下同)锰对钛酸锶钡-钛酸镁复相陶瓷微观形貌和介电性能的影响机理. 结果表明, 当锰的掺杂量小于1.5%时, Mn作为受主掺杂取代占据钙钛矿ABO3的B位, 因此导致居里点略微向高温偏移和相变扩散的发生, 锰的掺杂导致晶格畸变, 促进了晶粒生长, 使晶界相比例下降, 因此介电损耗随着锰掺杂量的增大而减小; 当锰的掺杂量为1.5%时, 介电损耗达到最小值, 继续增大掺杂量, 介电常数下降, 介电损耗上升.