钡钛比对钛酸钡陶瓷PTCR性能的影响

钡钛比是影响钛酸钡陶瓷PTCR性能的重要因素，采用固相反应法制备了不同钡钛比的样品，研究了钡钛比对钛酸钡陶瓷的显微结构和性能的影响。实验表明，轻微钛过量的系统具有较好的PTCR特性和较低的室温电阻率，与此相反，过量钡的存在将对烧结和半导化产生不利影响。并且钛过量的系统中过量的钛应该在一次配料中加入，否则由于钛在晶界上过量的偏析将导致难于烧结和过高的电阻。在实验的基础上对钛酸钡基PTCR陶瓷表面态的本质进行了讨论，认为受主表面态是VBa”和吸附O^2-共同作用的结果。     

新型碳-钛酸钡复合陶瓷膜的制备及介电性能研究

钛酸钡基陶瓷薄膜电容器以其高能量密度成为新能源领域独立动力电源和大容量储能电源的重要研究对象。本论文介绍了采用石墨纸作为电极材料、钛酸钡陶瓷作为介电材料制备陶瓷薄膜电容器的工艺,并利用石墨纸在高温环境下的渗碳来提高钛酸钡层的介电性能的方法,并研究了脱碳处理对复合材料介电性能的影响规律。制备了具有微观结构理想、介电性能优异的碳-钛酸钡复合陶瓷膜。结果表明陶瓷的晶粒大小为1μm左右,介电常数在100Hz 10V测试条件下达到3.9×105。     

纳米钛酸钡薄膜的制备及介电性能

以纳米钛酸钡粉体为原料,采用电泳沉积法制备得到较薄的钛酸钡薄膜。研究了电压、沉积时间和悬浮液浓度对钛酸钡薄膜成膜效果的影响,确定了钛酸钡薄膜的最佳成膜工艺条件:乙酰丙酮-乙醇的混合溶液质量浓度为75 g/L,直流电压为50 V,电泳5 min。采用反复电泳沉积和反复烧结的方法可以有效避免薄膜烧结过程中裂纹的产生。实验还发现钛酸钡薄膜的介点常数具有与钛酸钡陶瓷类似的温度特性。     

基于掺杂改性的钛酸钡基陶瓷介电性能的研究进展

首先概述了制备工艺即研磨时间、预烧温度、烧结温度、保温时间以及烧结工艺和制备方法即高温固相法、溶胶凝胶法、水热法、沉淀法以及其它新型制备方法对钛酸钡基陶瓷介电性能的研究进展;其次综述了单一元素及多种元素对钛酸钡陶瓷掺杂的研究进展;重点介绍了不同种类的元素及其含量对钛酸钡介电常数及介电损耗的影响;介绍了稀土元素的含量与其进入晶格间位的关系;最后对这一研究方向的未来及其发展做了展望。     

低温烧结BaTiO3基介电陶瓷的研究进展

低温烧结钛酸钡基陶瓷材料,有利于适应MLCC和LTCC的发展要求,并且降低能耗。本文综述了钛酸钡基陶瓷低温烧结方面的研究进展,包括各种低温烧结方法、机理和研究现状,着重介绍了助烧剂的作用机理,最后展望了钛酸钡基陶瓷低温烧结的发展趋势。     

掺杂改性对钛酸钡基陶瓷储能密度的影响

钛酸钡基陶瓷具备优良的电性能,是现代功能技术陶瓷应用最广泛的一类材料,是电子陶瓷元器件的主要原材料之一。本文综述了材料储能密度及影响因素、掺杂改性对钛酸钡基陶瓷介电性能的影响、钛酸钡基陶瓷材料的应用,并对钛酸钡基陶瓷材料Nb、Gd掺杂改性的研究进行了展望。     

退火温度对BaTiO_3薄膜的结构和介电性能的影响

采用溶胶-凝胶法制备Si（100）基片上的BaTi03陶瓷薄膜,并用红外光谱（IR）、x射线衍射（XRD）、扫描探针（SPM）等技术分析了钛酸钡凝胶的热解过程,以及不同退火温度下薄膜的晶粒、晶相、表面形貌、介电性能等指标。实验结果表明：高温有利于钛酸钡由立方相向四方相的转化;温度升高到1023K时,钛酸钡薄膜的表面形貌平整、均匀并具有良好的介电性能。     

退火温度对BaTiO3薄膜的结构和介电性能的影响

采用溶胶-凝胶法制备Si(100)基片上的BaTiO3陶瓷薄膜,并用红外光谱(IR)、x射线衍射(XRD)、扫描探针(SPM)等技术分析了钛酸钡凝胶的热解过程,以及不同退火温度下薄膜的晶粒、晶相、表面形貌、介电性能等指标.实验结果表明:高温有利于钛酸钡由立方相向四方相的转化;温度升高到1023 K时,钛酸钡薄膜的表面形貌平整、均匀并具有良好的介电性能.     

PTCR陶瓷材料的介电频响特性

研究了一种以钛酸钡为基的PTCR陶瓷在30kHz至300MHz频率范围内的室温介电频谱。该介电响应可近似地用Debye弛豫方程加以描述,但低频时电导率对介电常数虚部起主导作用。根据介电频谱的测量结果,分别得出了晶粒和晶界的电阻率和介电常数。     

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。     

Relation between electrical properties of aerosol-deposited BaTiO3 thin films and their mechanical hardness measured by nano-indentation

ABSTRACT: To achieve a high capacitance density for embedded decoupling capacitor applications, the aerosol deposition (AD) process was applied as a thin film deposition process. BaTiO3 films were fabricated on Cu substrates by the AD process at room temperature, and the film thickness was reduced to confirm the limit of the critical minimum thickness for dielectric properties. As a result, the BaTiO3 thin films that were less than 1-μm thick showed unstable electric properties owing to their high leakage currents. Therefore, to overcome this problem, the causes of the high leakage currents were investigated. In this study, it was confirmed that by comparing BaTiO3 thin films on Cu substrates with those on stainless steels (SUS) substrates, macroscopic defects and rough interfaces between films and substrates influence the leakage currents. Moreover, based on the deposition mechanism of the AD process, it was considered that the BaTiO3 thin films on Cu substrates with thicknesses of less than 1 μm are formed with chinks and weak particle-to-particle bonding, giving rise to leakage currents. In order to confirm the relation between the above-mentioned surface morphologies and the dielectric behavior, the hardness of BaTiO3 films on Cu and SUS substrates was investigated by nano-indentation. Consequently, we proposed that the chinks and weak particle-to-particle bonding in the BaTiO3 thin films with thicknesses of less than 0.5 μm on Cu substrates could be the main cause of the high leakage currents.     

Direct integration of dielectric all-ceramic thick films on a polymer substrate using room temperature fabrication

Direct integration of all-ceramic thick films and a polymer substrate has been realized for the first time without high temperature processing using the Room Temperature Fabrication method.Printable Li₂MoO₄-BaTiO₃ composite pastes with 0, 10, and 20 vol.% of BaTiO₃ were fabricated from the respective ceramic powders and water without organic additives or vehicles. The pastes were stencil printed on a polyimide substrate and dried at 120 °C without pressing or lamination.Using scanning electron microscopy, the films were observed to be in seamless contact with the substrate and to have a uniform microstructure. Relative permittivities of the ceramic films increased from 4.2 to 7.2 (at 2.5 GHz) and 4.5 to 7.5 (at 9.9 GHz) according to the vol.% content of the added BaTiO3, with corresponding dielectric losses from 10⁻³ to 10^-2.The results show that the room temperature fabrication method enables 2D printing of all-ceramic thick films on temperature-sensitive substrates.     

Ferroelectric BaTiO3/SrTiO3 multilayered thin films for room-temperature tunable microwave elements

Ferroelectric BaTiO₃/SrTiO₃ with optimized c-axis-oriented multilayered thin films were epitaxially fabricated on (001) MgO substrates. The microstructural studies indicate that the in-plane interface relationships between the films as well as the substrate are determined to be (001)_SrTiO3//(001)_BaTiO3//(001)_MgO and [100]_SrTiO3//[100]_BaTiO3//[100]_MgO. The microwave (5 to 18 GHz) dielectric measurements reveal that the multilayered thin films have excellent dielectric properties with large dielectric constant, low dielectric loss, and high dielectric tunability, which suggests that the as-grown ferroelectric multilayered thin films can be developed for room-temperature tunable microwave elements and related device applications.     

Preparation by chemical solution deposition and transparent conducting properties of LaRh1-xNixO3 thin films

Transparent conducting thin films have been widely used in lots of fields. The absence of high-performance hole-type transparent conducting thin films, however, seriously limits the wider applications. LaRhO₃ as a type of perovskite material shows hole-type conduction with semiconductor-like properties and no investigations have been carried out about transparent conducting properties on LaRhO₃ thin films. Here, LaRh_1-xNi_xO₃ (x = 0, 0.05, 0.1) thin films were firstly deposited by chemical solution deposition, showing epitaxial growth on single crystal SrTiO₃ (001) substrates with the epitaxial relationship of LaRhO₃(001)[110]||SrTiO₃(001)[110]. With the doping of Ni element, the surface morphology became denser. Hall measurements confirmed that the hole concentration was enhanced with Ni doping, resulting in the decreased resistivity. Low resistivity of 17.3 mΩ cm at 300K was obtained for the LaRh_0.9Ni_0.1O₃ thin films. The electrical transport mechanisms were investigated, showing thermal activation at high temperatures and variable range hopping model for the doped thin films at low temperatures. The transmittance within the visible range for all thin films was higher than 50%. The results will provide a feasible route to deposit hole-type transparent conducting LaRhO₃-based thin films.     

钛酸钡系无铅压电陶瓷的研究进展

钛酸钡（BaTiO3）压电陶瓷具有优异的电性能和低污染性，长期以来是人们重点研究的对象。本文综述了近年来BaTiO3系无铅压电陶瓷研究开发的几种体系与进展，着重介绍了BT--BNT和BT-BKT二元系无铅压电陶瓷的结构及性能。同时对BaTiO3系无铅压电陶瓷的发展趋势作了评述。     

BaTiO3基陶瓷PTC效应理论模型研究

综述了近年来提出的各种PTCR效应模型解释。但是从各种与传统模型相背的异常试验现象来看,建立完善的PTCR效应解释模型还需要做大量的工作。     

退火处理对钛酸钡微弧氧化铁电薄膜物相的影响

以工业纯钛板作为阳极,在Ba(OH)2溶液中微弧氧化制得BaTiO3薄膜。研究了BaTiO3薄膜的表面形貌和物相组成,着重研究了退火处理对BaTiO3薄膜物相的影响。微弧氧化所得薄膜表面凹凸不平,且存在大量分布不均的孔洞,主要由六方相BaTiO3组成,经不同温度退火后,其物相组成发生很大变化。在1 100°C下退火1 h后,薄膜中开始出现四方相BaTiO3;随着热处理温度的升高和保温时间的延长,更多的BaTiO3由六方相向四方相转变。但高温退火过程中基体Ti与微弧氧化膜反应形成的氧化物层会影响薄膜的铁电性能。     

钛酸钡系薄膜的制备方法、性质及应用

综述了制备钛酸钡系薄膜的各种方法，如：溶胶-凝胶法、有机金属化学气相沉积法、射频磁控溅射法、脉冲激光沉积法等，其中主要对溶胶-凝胶法和射频磁控溅射法的制备原理及工艺特点进行了讨论。介绍了钛酸钡薄膜的性质和掺杂后(主要是锶掺杂)对薄膜电性能的影响，对它们的应用现状进行了概括，并对钛酸钡系薄膜的发展趋势做了展望。