掺杂氧化铌对钛酸锶钡铁电陶瓷材料显微结构和介电性能的影响

钛酸锶钡(barium strontium titanate,BST)铁电陶瓷材料的介电常数(ε)随外加直流电场的变化呈现非线性特性.纯BST材料由于较高的ε和较大的介电损耗(tanδ)不能满足移相器介质材料的要求.通过在BST中添加氧化铌(Nb2O5)来改善BST铁电陶瓷材料的介电性能.结果表明:在BST体系中微量掺杂Nb2O5,Nb5 以取代Ti4 的方式存在于钙钛矿的晶格中,形成均匀的固溶体Ba0.5Sr0.5Ti1-xNbxO3.随Nb5 添加量的增加,Curie峰逐渐变宽,峰高逐渐降低,相变弥散效应增强.Nb5 的掺杂能显著降低并稳定BST陶瓷的tanδ,改善BST体系的介电性能.     

钛酸锶钡铁电陶瓷材料掺杂改性研究进展

综述了最近几年国内外专家对钛酸锶钡(BST)铁电陶瓷材料的掺杂改性方面的研究情况,介绍了不同掺杂物对BST材料性能的影响,简述了BST陶瓷材料的应用趋势。论述了掺杂物掺杂改性材料的组成、结构和性能之间的关系,提出了研究中需要解决的一些问题,展望了钛酸锶钡电介质材料掺杂改性的发展方向。     

CaZrO3掺杂对(Ba,Sr)TiO3铁电电容器陶瓷性能的影响

研究了CaZrO3掺杂量对(Ba,Sr)-TiO3(barium strontium tianate,BST)铁电电容器陶瓷介电性能的影响．得到了CaZrO3掺杂量与：BST性能的关系。用扫描电镜和X射线衍射研究了CaZrO3。掺杂量对BST陶瓷微观结构和相结构的影响,探讨了CaZrO3掺杂改性BST陶瓷的机理。结果表明：适量的CaZrO3掺杂,可得到最佳综合性能的BST。CaZrO3掺杂明显促使：BST细晶化,有较强的移峰和压峰效应,能使四方相晶轴比(c／c)降低,提高材料的介电常数并改善材料的介温特性,过量CaZrO3掺杂使衍射峰宽化,会使材料的介电常数下降。通过研究获得了高介高压高稳定的电容器陶瓷。     

B2O3-Li2O掺杂低温烧结Ba0.6Sr0.4TiO3陶瓷的介电性能

采用传统陶瓷制备工艺,通过B2O3-Li2O的有效掺杂,低温液相烧结制备了Ba0.6Sr0.4TiO3(BST)陶瓷,并对其介电性能进行了研究.X射线衍射分析和介电性能测试结果表明:适量B2O3-Li2O掺杂的BST陶瓷,经97S℃烧结4h,所得样品的主晶相为钙钛矿结构,未出现明显的杂相;随B2O3-Li2O掺杂量的增加,BST陶瓷材料的介电常数减小,Curie峰变得弥散宽化,介电损耗则与未掺杂BST陶瓷的保持一致,即在0.003以下:适量B2O3-Li2O的掺杂对BST陶瓷材料的Curie温度和介电调制性能影响不大.     

Ag~+掺杂钛酸锶钡基玻璃陶瓷的显微结构和介电性能

采用熔融法制备了钛酸锶钡（barium strontium titanate,BST）基玻璃,然后将此玻璃样品在不同的温度下进行热处理得到BST基玻璃陶瓷,采用差热分析研究了BST基玻璃陶瓷析晶过程中的热力学特征,用扫描电子显微镜和X射线衍射分别分析了玻璃陶瓷的显微结构和相结构,并且系统研究了该玻璃陶瓷的介电特性以及耐击穿电场强度。结果表明：0.3%（质量分数）Ag＋掺杂时,BST基玻璃中BST相的析晶温度从885℃下降到840℃,有利于玻璃体中BST晶体的析出。另外,Ag＋的掺杂有利于提高BST基玻璃陶瓷的介电常数,同时能维持较低的介电损耗。此外,Ag＋掺杂能够提高BST基玻璃的耐击穿电场强度,其在800℃热处理后,可达96.3 kV/mm,高于未掺杂Ag＋的BST基玻璃的52.5kV/mm。     

国内工业陶瓷文献题录及文摘(二十九)

示例:顺序号文献题名(文种,中文略)·刊名,年,期本栏报道的是我刊编辑部最近收集到的工业陶瓷文献。读者如需复印,可直接与我刊编辑部联系,但请写明“顺序号、文献题名、刊名、年、卷、期”等内容。收费标准:每篇18元(包括检索费、复印费及邮寄费)。2008070掺杂氧化铌对钛酸锶钡铁电陶瓷材料显微结构和介电性能的影响·硅酸盐学报,2007,12钛酸锶钡(barium strontium titanate,BST)铁电陶瓷材料的介电常数(ε)随外加直流电场的变化呈现非线性特性。纯BST材料由于较高的ε和较大的介电损耗(tanδ)不能满足移相器介质材料的要求。通过在BST中添加氧化铌(Nb2O5)来改善BST铁电陶瓷材料的介电性能。结果表明:在BST体系中微量掺杂Nb2O5,Nb5+以取代Ti4+的方式存在于钙钛矿的晶格中,形成均匀的固溶体Ba0·5Sr0·5Ti1?xNbxO3。随Nb5+添加量的增加,Curie峰逐渐变宽,峰高逐渐降低,相变弥散效应增强。Nb5+的掺杂能显著降低并稳定BST陶瓷的tanδ,改善BST体系的介电性能。2008071热处理工艺对钙锶铋钛铁电薄膜性能的影响·硅酸盐学报,2007,12用溶胶...     

CaTiSiO5掺杂对钛酸钡锶陶瓷介电性能的影响

采用传统固相烧结法,利用X-射线衍射仪(XRD)、扫描电镜(SEM)等方法系统研究了CaTiSiO5掺杂量对(Ba,Sr) TiO3(barium strontium titanate,BST)基电容器陶瓷介电性能和微观结构的影响.结果表明:CaTiSiO5掺杂的BST陶瓷材料的介电损耗都比较小,但是对材料居里峰的移动和展宽效应都明显.随着CaTiSiO5掺杂量的增加,BST陶瓷的介电常数(εr)先增大然后减小,介电损耗(tanδ)先增大然后减小,变化不大,交流耐压强度(Eb)先增大然后减小,容温变化率先减小然后增大.当掺杂CaTiSiO5质量分数为0.8％时,BST陶瓷的综合介电性能较好:介电常数(εr)=2540,介电损耗(tanδ)=0.0036,耐压强度(Eb)=5.6 kV/mm(AC),在-30～85℃温度范围内,容温变化率为-18.9％ ～ 20.6％,容温特性符合Y5S特性.     

二氧化硅掺杂钛酸锶钡陶瓷的介电性能与电卡效应

采用传统的固相反应法制备二氧化硅（SiO₂）掺杂钛酸锶钡（Ba_0.65Sr_0.35TiO₃,BST）陶瓷（BST+x%SiO₂）,研究了掺杂二氧化硅对BST陶瓷的物相、微观形貌、介电性能及电卡效应的影响。结果表明：掺杂二氧化硅并未改变BST陶瓷的晶型结构,但有助于提升晶粒的均匀性和材料介电性能频率的稳定性。随着二氧化硅掺杂量增加,BST陶瓷的介电常数呈现单调递减趋势,介电弥散特性逐渐增强。二氧化硅的掺杂有利于提升BST陶瓷的电卡性能,其中BST+3%SiO₂陶瓷具有最优的电卡效应,在30 ℃下可获得最大电卡绝热温变（ΔT_max）,ΔT_max和ΔT_max/ΔE分别为1.6 ℃、8.00×10 ^-7 ℃·m/V,电卡效应半峰宽（T_span）为10 ℃左右。     

La~(3+)掺杂钛酸铋钠基无铅陶瓷的压电性能与介电弛豫行为

采用冷等静压成型和密闭烧结工艺,制备了具有微晶结构的稀土离子La3+掺杂0.9TNa0.5Bi0.5TiO3-0.03K0.5Na0.5NbO3基无铅压电陶瓷体系.研究了该体系陶瓷的相结构,显微结构与介电、压电性能.结果表明:在掺杂范围内(0.015≤x≤0.105),La3+可完全固溶进陶瓷晶格形成单一的钙钛矿相.采用等静压成型工艺可明显改善陶瓷的显微结构,使晶粒细化,进而提高材料的压电性能.该陶瓷具有弥散相变和频率色散特征,为典型的弛豫型铁电体.随着La3+掺杂量的增加,材料的铁电-反铁电相变温度下降,Curie温度提高,相对介电常数、介电损耗和压电常数逐渐减小,弛豫特征愈明显.     

Bi_4Ti_3O_(12)掺杂(Ba,Sr)TiO_3基电容器陶瓷介电性能研究

采用传统固相法制备了Bi_4Ti_3O_(12)掺杂(Ba_(0.71),Sr_(0.29))TiO_3(BST)陶瓷。研究了Bi_4Ti_3O_(12)掺杂量对BST电容器陶瓷介电性能、物相组成和微观结构的影响。结果表明:随着Bi_4Ti_3O_(12)掺杂的增加,BST陶瓷的相对介电常数逐渐减小,介电损耗先减小然后增大,Bi_4Ti_3O_(12)掺杂后的BST陶瓷仍为钙钛矿结构。当Bi_4Ti_3O_(12)掺杂量为1.6 wt%时,BST陶瓷的综合介电性能最好,εr为3744,tanδ为0.0068,ΔC/C为+1.70%,-44.61%,容温特性符合Y5V特性。     

Enhanced dielectric loss of Mg doped Ba0.7Sr0.3TiO3 ceramics

The effect of MgO doping on the structural, microstructural and dielectric properties of Ba_0.7Sr_0.3TiO₃ (BST) ceramic from the point of view of its application in microwave tunable devices has been studied. All the samples crystallize into perovskite structure. There is significant reduction in the value of loss factor with the increase in Mg-level, the dielectric constant and tunability are also reduced with the increase in Mg-level. Interestingly, the Fig. of merit of the material is found to be enhanced with increase of Mg-doping. The observed dielectric properties are explained on the basis of defect chemistry involved when Mg is doped in Ba_0.7Sr_0.3TiO₃ ceramics. The effect of dc field on the dielectric constant and the dielectric breakdown strength of the paraelectric phase Mg doped BST ceramic samples are also studied.     

Mn和Zr共掺杂钛酸锶钡/氧化镁复合陶瓷材料的微结构和介电性能

通过固相反应法制备Mn、Zr共掺杂钛酸锶钡/氧化镁陶瓷粉体,经干压成型后在空气气氛中于1450℃烧结4h,通过扫描电子显微镜和X射线衍射研究了ZrO2和MnO2共掺杂的Ba0.6Sr0.4TiO3/MgO复合陶瓷材料的微结构和介电性能。结果表明:ZrO2可以显著降低材料的介电常数和介电损耗,有效提高了陶瓷材料的温度稳定性;随ZrO2添加量的增加,体系的晶胞参数略有增加,MgO在钛酸锶钡中以独立相的形式存在;制备出的BST铁电陶瓷材料的25℃相对介电常数较低(εr<110),介质损耗小于1.0×10–3(在频率为10kHz时),温度系数小于6.012×10–3,可调性大于20%(8.0kV/mm),适用于制作移相器。     

Dielectric and microwave properties of barium strontium titanate (BST) thick films on alumina substrates

The dielectric and microwave properties of barium strontium titanate (BST) thick films on alumina substrates have been investigated. The BST films were screen printed and sintered at temperatures below 1300 °C. At temperatures below the Curie point the BST films exhibit tunability in the range 15–35% under a DC bias field of 2 kV/mm. The dielectric loss is critically dependent on film thickness with lower losses (<10⁻²) for the thicker films (>100 μm). A relaxation process appears to take place for the BST films in the MHz to GHz frequency regime. The variation of permittivity with bias field exhibits hysteretic behaviour in both the ferroelectric and paraelectric regions. This is believed to arise due to the non-uniform composition and existence of micro/nano-polar phases in the films.     

Effects of CuO Doping on the Microstructural and Dielectric Properties of Ba0.6Sr0.4TiO3 Ceramics

This study investigates the effect of CuO on the sintering behavior, dielectric properties, and microstructures of Ba_0.6Sr_0.4TiO₃ (BST) ceramics. The ceramics were sintered in air at temperatures ranging from 1000° to 1230°C. It is found that a small amount of added CuO (0.6 mol%) can significantly increase the density and improve the dielectric properties of BST ceramics. Doped BST ceramics can be sintered to a density >95% of the theoretical density at 1150°C. scanning electron microscopic observations show that the BST grain sizes increase with increasing amounts of CuO. No secondary phases in the BST ceramics are observed using X-ray diffraction pattern for CuO additions up to 0.9 mol%. However, compositional analysis using transmission electron microscopy-EDX for the BST ceramics with 0.9 mol% CuO sintered at 1150°C showed that a small level of secondary phase formation is present. On the other hand, large dislocations are observed for BST with 0.6 mol% CuO addition as a result of lattice distortion, which creates the vacancy condensation because of the atomic mismatch in the solid solutions. Optimal CuO doping concentrations can reduce the loss tangents of BST that can also ensure a high dielectric constant. When the doping concentration of CuO is 0.6 mol% and the ceramic is sintered at 1150°C, the BST ceramic has the following properties at 1 MHz: dielectric constant=4094, tan δ=0.55%.     

掺杂对CeO2基电解质材料性能的影响研究进展

掺杂CeO₂基电解质是中低温固体氧化物燃料电池（SOFC）理想的电解质材料。首先阐述了掺杂CeO₂基电解质结构与性能的关系,接着介绍了金属离子掺杂对CeO₂基电解质晶体结构和电子结构的影响,重点综述了单元素掺杂和双元素掺杂对CeO₂基电解质性能的影响。通过分析得出：稀土金属元素单掺杂比碱土金属元素单掺杂更能显著提高CeO₂基电解质的导电性和可烧结性,但稀土氧化物的原料成本要远高于碱土氧化物;双元素掺杂比单元素掺杂具有更多的氧空位无序度和更小的氧离子迁移激活能,因此在提高CeO₂基电解质的离子电导率方面更有优势。总结了CeO₂基电解质材料的掺杂规律及构效关系,以期对制备出性能更加优异的CeO₂基电解质起到一定的指导作用。     

Nanocrystalline Barium Strontium Titanate Ceramics Synthesized via the “Organosol” Route and Spark Plasma Sintering

Dense nanocrystalline barium strontium titanate Ba_0.6Sr_0.4TiO₃ (BST) ceramics with an average grain size around 40 nm and very small dispersion were obtained by spark plasma sintering at 950°C and 1050°C starting from nonagglomerated nanopowders (~20 nm). The powders were synthesized by a modified “Organosol” process. X‐ray diffraction (XRD) and dielectric measurements in the temperature range 173–313 K were used to investigate the evolution of crystal structure and the ferroelectric to paraelectric phase transformation behavior for the sintered BST ceramics with different grain sizes. The Curie temperature T_C decreases, whereas the phase transition becomes diffuse for the particle size decreasing from about 190 to 40 nm with matching XRD and permittivity data. Even the ceramics with an average grain size as small as 40 nm show the transition into the ferroelectric state. The dielectric permittivity ε shows relatively good thermal stability over a wide temperature range. The dielectric losses are smaller than 2%–4% in the frequency range of 100 Hz–1 MHz and temperature interval 160–320 K. A decrease in the dielectric permittivity in nanocrystalline ceramics was observed compared to submicrometer‐sized ceramics.     

Relaxor Ferroelectric Behavior in Barium Strontium Titanate

The development of barium strontium titanate‐based tunable dielectrics is currently hindered by high losses in the paraelectric phase. Barium strontium titanate (BST) thin films and ceramics show a range of ferroelectric transition behavior, from normal, diffuse, and relaxor‐like ferroelectric responses, depending on the sample preparation route. Rayleigh analysis, the temperature‐dependent dielectric response, and the optical second harmonic generation were used to characterize the ferroelectric response of bulk and thin film BST. Ferroelectricity is observed to persist in BST for 30°C above the global phase transition temperature in ceramics and over 50°C in thin films. Piezoresponse force microscopy on BST ceramics with extensive residual ferroelectricity reveals the coexistence of nanoscale polar regions, typical of relaxor ferroelectrics, as well as micrometer scale domain structures. The nature of the phase transition was probed using electron energy loss spectroscopy and found to correlated with the nanoscale A‐site chemical inhomogeneity in the samples.     

Bi掺杂Ba0.6Sr0.4TiO3陶瓷的研究

本文采用传统的陶瓷工艺合成了Ba0.6Sr0.4TiO3陶瓷,研究了Bi掺杂对材料参数ε、tanδ和E的影响,并探讨了相关的掺杂改性机理。结果表明：适量的Bi能够改善陶瓷的介电性能,同时细化陶瓷的晶粒尺寸。