纳米钛酸钡的掺杂对陶瓷性能的影响

采用掺杂纳米级钛酸钡和碳酸锰的方法,观察了掺杂不同量纳米级钛酸钡和碳酸锰后的钛酸钡坯片烧结所得陶瓷表面的显微组织形貌的变化,研究了单一掺杂纳米级钛酸钡、单一掺杂碳酸锰、复合掺杂碳酸锰+纳米级钛酸钡对陶瓷制品晶粒尺寸与介电性能的影响。结果表明：掺杂纳米级钛酸钡对钛酸钡陶瓷制品的介电性能有显著的提升,但是随着掺杂量的进一步增加,其介电性能的变化不大;掺杂碳酸锰对钛酸钡陶瓷晶粒的细化效果优于掺杂纳米级钛酸钡的效果;复合掺杂1%（质量分数,下同）碳酸锰+1%纳米级钛酸钡所得陶瓷的致密性高于单一掺杂1%碳酸锰的效果。     

掺杂Y2O3对BaZr0.1Ti0.9O3陶瓷电介质性能的影响

研究了掺杂量不同的Y2O3对BaZr0.1R.9O3微观形貌及介电性能的影响.实验发现:通过XRD物相分析,所有试样均形成典型的钙钛矿结构的主晶相,说明钇掺杂并未改变锆钛酸钡的晶型结构.一定量的Y2O3可抑制晶粒的长大,使晶粒细化,降低气孔率,试样得到致密化.当Y2O3的掺入量为0.05mol％时,试样的介电损耗最小.Y2O3掺杂可提高锫钛酸钡陶瓷居里点处的介电常数,展宽介电温谱,提高材料的实际应用性.     

钒掺杂钛酸钡基陶瓷的制备和表征

采用溶胶-凝胶一步法制备了钒掺杂钛酸钡基陶瓷,通过XRD、SEM等分析检测手段对粉体和陶瓷样品进行了表征。研究了V掺杂量的不同对钛酸钡基陶瓷相组成、微观结构及介电性能的影响规律。研究表明:样品为四方相钙钛矿结构,随着V掺杂量的增加,陶瓷晶粒尺寸增大,介电常数与介电损耗总体在降低,并使其居里温度向高温方向移动。当陶瓷中V的掺杂量为0.1%(mol)时,介电常数与密度达到最大值,室温介电常数(ε_r)和介电损耗(tanδ)分别为2886和3.56%。     

镧、铈掺杂对钛酸钡基介电陶瓷性能的影响

为了改善钛酸钡陶瓷的介电性能,采用溶胶凝胶法,制备了镧、铈掺杂的钛酸钡基介电陶瓷,研究了镧、铈2种稀土氧化物对其介电性能、耐压程度等性能的影响以及与显微结构的关系.实验表明:2种稀土元素对钛酸钡陶瓷的晶粒生长有较大的抑制作用,镧和铈的掺杂量在1.0%(物质的量分数)左右对钛酸钡陶瓷的介电性能有很好的改善作用.但镧离子和铈离子在钛酸钡中的离子取代情况有所不同,因而,改善性能的作用不同.镧掺杂钛酸钡陶瓷性能好于铈掺杂的钛酸钡陶瓷,掺杂物质的量分数为1.0%的镧掺杂钛酸钡陶瓷的相对介电常数大于4000,从室温到125℃温度范围内,介电常数的温度系数小于10%,击穿场强大于7.5kV/mm.     

化学包覆法制备Ho^(3+)掺杂钛酸钡基X8R细晶陶瓷EI北大核心CSCD

采用化学包覆法将Ho_2O_3包覆在纳米级钛酸钡粉体表面,通过烧结将Ho^(3+)扩散到钛酸钡晶粒中,调节其介电性能,研究了不同Ho^(3+)掺杂量对Ba Ti O3基陶瓷相组成、微观结构和介电性能的影响。X射线衍射和扫描电子显微镜分析结果表明:Ho^(3+)改性陶瓷样品均为赝立方相,Ho^(3+)的加入能抑制晶粒生长,改善陶瓷微观结构,有利于制备均匀的细晶陶瓷。透射电子显微镜观察显示,包覆层的厚度约为2 nm,包覆Ho_2O_3有助于陶瓷烧结过程中形成"核-壳"结构晶粒,能显著改善钛酸钡基陶瓷的介电温度稳定性,提高绝缘电阻。当Ho^(3+)掺杂量为2.0%时,陶瓷的相对介电常数为1 612,ΔC/C(-55~150℃)<±15%,满足EIA X8R电容器的温度特性。     

化学包覆法制备Ho~(3+)掺杂钛酸钡基X8R细晶陶瓷

采用化学包覆法将Ho_2O_3包覆在纳米级钛酸钡粉体表面,通过烧结将Ho~(3+)扩散到钛酸钡晶粒中,调节其介电性能,研究了不同Ho~(3+)掺杂量对Ba Ti O3基陶瓷相组成、微观结构和介电性能的影响。X射线衍射和扫描电子显微镜分析结果表明:Ho~(3+)改性陶瓷样品均为赝立方相,Ho~(3+)的加入能抑制晶粒生长,改善陶瓷微观结构,有利于制备均匀的细晶陶瓷。透射电子显微镜观察显示,包覆层的厚度约为2 nm,包覆Ho_2O_3有助于陶瓷烧结过程中形成"核-壳"结构晶粒,能显著改善钛酸钡基陶瓷的介电温度稳定性,提高绝缘电阻。当Ho~(3+)掺杂量为2.0%时,陶瓷的相对介电常数为1 612,ΔC/C(-55~150℃)±15%,满足EIA X8R电容器的温度特性。     

Nd掺杂钛酸钡基陶瓷的制备及性能研究

采用溶胶-凝胶一步法制备了Nd掺杂锆钛酸钡基陶瓷,通过XRD、SEM等分析检测手段对样品进行表征。研究了Nd掺杂量的不同对其微观形貌及介电性能的影响。研究表明:随着Nd掺杂量的增大,钛酸钡基陶瓷的晶粒尺寸增大,介电常数呈现出先增大后减小的变化趋势,介电损耗逐渐减小;当Nd掺杂量为摩尔分数0.07%时,陶瓷较为致密,其室温介电常数达到最大值16032,介电损耗较小为0.0046。     

Al掺杂对钛酸钡基陶瓷微观形貌及性能的影响

采用溶胶-凝胶一步法制备了Al掺杂钛酸钡基陶瓷。利用XRD、SEM等分析检测手段对陶瓷样品进行表征。探讨了Al掺杂量对钛酸钡基陶瓷相组成、微观形貌、介电常数、介电损耗及介电弛豫的影响。研究表明:Ba Ti O3基陶瓷粉体样品均为单一的钙钛矿结构;随着Al掺杂量的增大,陶瓷的晶粒尺寸逐渐减小,室温介电常数呈现出减小的变化趋势,而居里温度略有增加;当Al掺杂量为0.03mol%时,陶瓷的晶粒大小均匀,其室温介电常数达到最大值3427,介电损耗小于4%。     

Zr掺杂对BaTiO3陶瓷微观形貌及性能的影响

采用溶胶-凝胶法制备了锆掺杂的钛酸钡陶瓷,通过XRD、SEM等分析检测手段对所得锆钛酸钡陶瓷样品进行了表征。系统地研究了Zr掺杂对BaTiO_3基陶瓷相组成、微观形貌和介电性能的影响。结果表明,锆钛酸钡陶瓷样品均为单一的立方相钙钛矿结构,晶粒大小均匀,随着Zr掺杂量的增加,陶瓷晶粒尺寸先增大后减小,孔隙逐渐增多,介电常数先增大后减小,介电损耗先减小后增大。     

Fe掺杂对钛酸钡陶瓷微观结构与介电性能的影响

采用溶胶-凝胶一步法制备了Fe掺杂钛酸钡陶瓷。利用XRD和SEM表征分析了陶瓷样品的物相及微观形貌,并研究了Fe掺杂量的不同对其微观形貌及介电性能的影响规律。研究表明:当Fe掺杂量为摩尔分数0.10%时,晶粒大小均匀,陶瓷致密性最好,其室温介电常数达到最大值2710,介电损耗较小为0.8%。     

Nd(OH)3-Co3O4-Nb2O5纳米复合掺杂BaTiO3基陶瓷研究

钛酸钡(BaTiO3)材料具有铁电、压电、热电、介电等特性,广泛用于制造高介电容器、热敏电阻和换能器等,特别是用作多层陶瓷电容器(MLCC)的基质材料.目前,MLCC向高可靠性、高比容(小尺寸大容量)、低成本的趋势发展.因此,制备高纯超细的BaTiO3粉体以及掺杂改性的研究,是该领域研究的热点.本文制备了Nd(OH)3...     

Preparation of Small-Grained and Large-Grained Ceramics from Nb-Doped BaTiO3

Barium titanate powders with average grain sizes of 0.07 and 0.65 μm were coated with an organic Nb ester, using a liquid-solid mixing process. Small-grained (1 to 3 μm) ceramic dielectrics from both powders and large-grained (>50 μm) dielectrics from the 0.65 μm powder were fired using 0 to 2 at.% Nb. Microstructures, densities, and electrical resistivities were investigated.     

钛酸锶钡超细粉体的研究进展

钛酸锶钡超细粉体是一种重要的电子陶瓷材料，具有优良的光、电、磁性能，广泛用于电容器、电光器件、铁电存储器等电子元件的制备，其制备方法也有很多。详细介绍了钛酸锶钡超细粉体主要的制备方法，如：溶胶—凝胶法、燃烧法、直接沉淀法、高温固相法、水热法，也概括了其在发光及陶瓷行业的应用。     

钛酸钡基电子陶瓷材料的改性进展

钛酸钡基电子陶瓷材料广泛应用于电容器、集成电路、传感器及热敏电阻等领域。高容量、小型化、抗击穿及低损耗等工业需求对钛酸钡基电子陶瓷材料的性能提出更高的要求,改性则是提高陶瓷材料性能的主要手段。综述了近年来钛酸钡基电子陶瓷材料在掺杂改性、复合改性及物理改性方面的研究进展。分析了钛酸钡基电子陶瓷材料在改性中存在的问题,比如：常规元素掺杂制备参数优化不足、稀土元素掺杂种类偏少、包覆效果待提升、聚合物陶瓷复合体综合性能欠佳、烧结工艺尚待优化等。提出了解决方法,比如：探索多种元素掺杂、优化工艺参数、改进包覆与聚合方式等。指出了钛酸钡基电子陶瓷材料的未来发展方向,即：强化烧结过程中晶粒尺寸、晶体形状、组分调控的机理研究,选取更多稀土元素进行改性,探索包覆掺杂改性、聚合物复合改性等新工艺。     

掺杂离子及掺杂工艺对钛酸钡性能的影响

钛酸钡基陶瓷是一种新兴的多功能电子陶瓷材料，由于其优异的电学性能而在很多领域有着广泛的应用，掺杂离子以及掺杂工艺对钛酸钡的性能有显著的影响。对常用的几种掺杂离子，如钙、镁、铅、锶、锆、锡和稀土元素，以及各种掺杂工艺对钛酸钡性能的影响进行了简单评述，并预测了未来的研究方向。     

Grain-Size Effects on Diffuse Phase Transitions of Sol-Gel Prepared Barium Titanate Ceramics

Barium titanate ceramic samples, obtained by sol-gel methods, having different grain sizes have been analyzed by diffuse phase transition techniques. We performed a study of the influence of each method on the phase transition interval and on the Landau parameters of the ferroelectric phase transition of these materials. The results show the existence of a relationship between the diffuse character of the transition and the grain size of the sample. The method of fitting dielectric data presented here allows us to compare ceramics with single crystals and then analyze the sol-gel process used to obtain them.     

Relaxation and conduction mechanism of PVA: BYZT polymer composites by impedance spectroscopy

Frequency dependent dielectric, modulus, impedance and AC conductivity study of Poly Vinyl Alcohol with 25 vol.% of Yttrium modified Barium Zirconium Titanate ceramic have been investigated. The single phase Yttrium modified Barium Zirconium Titanate ceramics have been synthesized by conventional solid state route. The relaxation mechanism of dielectric and modulus study is due to the segmental motion of polymer chain along with the dipole orientation of ceramic in the polymer composite. The Nyquist plot of impedance shows two semicircles, which represents the bulk and interfacial effect of polymer composites. The activation energy decreases with incorporation of higher Yttrium modified Barium Zirconium Titanate ceramics in the polymer matrix due to the even distribution of ceramic in the polymer composite. The different activation energy obtained from conduction and relaxation of the composite indicates that various mechanisms are involved in the conduction and relaxation process.     

Effect of Additives on the Crystallization Kinetics of Barium Strontium Titanate Glass–Ceramics

Barium strontium titanate (BST) has been targeted as one potential ferroelectric glass–ceramic for high-energy density dielectric materials. Previous testing has shown that the dielectric constant of these materials was as high as 1000 and the dielectric breakdown strength up to 800 kV/cm. This did not, however, result in exceptional energy density (∼0.90 J/cc). In order to increase overall energy density refining agents can be added to the melt, but the nucleation and growth of the ceramic particles can also play a role. Therefore, in this study the crystallization kinetics were studied to more fully understand how BST phase forms so that the optimal energy density could be obtained. It was determined that the activation energy of the crystallization of BST 70/30 glass–ceramic is approximately 430 kJ/mol which is close to the dissociation energy of Si–O bonds. The Avrami parameter was found to be ∼3 meaning that three-dimensional growth is dominant and the mechanism of growth was interface controlled.     

Effective elastic properties for unpoled barium titanate

Piezoelectric devices with complex electrode geometries may contain regions of ferroelectric material that remain unpoled. It is desirable to account for these non-piezoelectric regions for device optimization, since the unpoled and poled material properties differ. The lack of published elastic properties for unpoled ferroelectrics, specifically the numerous commercial PZT compositions, reflects the difficulty of experimental measurement. In this work, a method was developed to predict unpoled properties from more commonly available poled material data. Barium titanate was chosen for study as a representative ferroelectric, with both single crystal and polycrystalline (ceramic) properties available. Finite element micro-mechanical models were created with a focus on computational economy. This allowed larger ensembles of results to be computed, providing accurate effective compliances when averaged. The modelling methodology predicted the elastic properties for unpoled barium titanate to within ∼10% of measured experimental values.