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Thick BaTiO3 films were prepared on platinum metallic foils by the electrophoretic deposition (EPD) technique using BaTiO3 nanoparticles. In order to increase the density of the thick film, the green film was pressed under an isostatic pressure of 200 MPa before high-temperature sintering. The microstructures of deposited films were examined using X-ray diffraction and scanning electron microscopy techniques. Dielectric properties of the thick films were investigated. As the films grow thicker, the dielectric constant increases gradually and the dielectric loss decreases slightly. The experimental results indicate that isostatic pressing is an effective method to process thick films with dense microstructure and better dielectric properties. 相似文献
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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. 相似文献
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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。 相似文献
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Hanna Kähäri Merja Teirikangas Jari Juuti Heli Jantunen 《Journal of the American Ceramic Society》2014,97(11):3378-3379
Lithium molybdate disks were fabricated by moistening water‐soluble Li2MoO4 powder with deionized water and compressing it under a pressure of 130 MPa. Disks were postprocessed at room temperature, at 120°C, and at 540°C, which is a common sintering temperature for Li2MoO4. Regardless of the postprocessing temperature, densities as high as 87%–93% of the theoretical value were achieved. The X‐ray diffraction patterns of processed disks were all the same with no signs of hydrates or constitutional water. The samples also exhibited very similar microstructures and microwave dielectric properties with a relative permittivity of 4.6–5.2 and a Q × f value of 10 200–18 500 at 9.6 GHz, depending on the postprocessing temperature. 相似文献
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采用复合溶胶凝胶法制粉技术结合传统陶瓷制备工艺,制备了(1-x)BaTiO_3-xKNbO_3陶瓷,对其晶相特征、介电及压电铁电性能进行了研究。在1250℃下烧结的陶瓷形成了单一相的钙钛矿结构固熔体。介电常数随着KNbO_3含量的增加先减小后增加,KNbO_3的加入降低了陶瓷的介电损耗。样品的居里温度也在120℃之间波动。KNbO_3的加入使样品的压电常数d_33值逐渐减小。样品BT的d_33值最大,为140pC/N。样品的剩余极化强度(Pr)随着KNbO_3含量的增加而减小,由7μC/cm~2降为3μC/cm~2;矫顽场强(EC)随KNbO_3含量的增加呈现出变小的趋势,样品BT-KN10的矫顽场强(E_C)为4kV/cm。 相似文献
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Hong‐Yang Lu 《Journal of the American Ceramic Society》2014,97(7):2256-2263
Commercial EIA‐Y5V base‐metal‐electrode multilayer ceramic capacitors (BME‐MLCCs) made of (CaO+ZrO2)‐doped BaTiO3 are analyzed for the microstructure and investigated for its relation to dielectric properties. The characteristic diffuse scattering (DS) intensities observed in BaTiO3 ceramics and the featureless “solid‐solution” grains in Y5V capacitor chips are originated from multiple Ti sites in the dynamic BaTiO3 structure. The pseudo‐cubic (PC)‐grains retaining the overall cubic (C‐) symmetry metastably at room temperature are embedded with polar nanoregions (PNRs) in the ferroelectric (FE) tetragonal (T‐), and rhombohedral (R‐) phases, as revealed by high‐resolution transmission electron microscopy (HRTEM). The presence of PNRs contributes effectively to large relative permittivity εr ≈ 13 200 at 25°C. The FE T‐domains grow from within PC‐grains at the expense of embedded PNRs after prolonged annealing by extending “oxidizing firing” at 950°C in pO2 = 10?7 atm. These domains contain less Zr with otherwise homogeneously distributed solutes in PNR‐dispersed PC‐grains. Although preserving the relaxors characteristics, εr is reduced to ~11 000 after 12 h, and then to ~9000 after 24 h annealing. The reduction in εr is attributed to the annealing‐induced FE T‐domains grown at the expense of PNRs in PC‐grains. The Vögel–Fulcher analysis indicates that Y5V ceramics are in the relaxor FE category, containing PNRs derived from polarization frustration. 相似文献
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通过测定超重力法制备的纳米钛酸钡悬浮体的Zeta电位和团粒尺寸分布,确定了纳米BaTiO3在水中稳定分散的基本条件,制备了不同体积分数的悬浮体并研究了其流变学特性. 该纳米BaTiO3在水中的等电点约为pH 2.8,加入分散剂PAA-NH4后,颗粒零电点向更低pH值移动;当分散剂用量为干粉量的1.2%(w)时,悬浮体中平均团粒尺寸最小,分散效果最佳. FT-IR分析证明颗粒表面上PAA-NH4的吸附为物理化学吸附. 制备了体积分数高达45%的纳米BaTiO3悬浮体,其流变特性表现为剪切变薄行为,流延成型的BaTiO3陶瓷生坯片具有较高的相对密度(55.4%). 相似文献
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《Ceramics International》2016,42(10):11692-11699
Sm/Mn codoped BaTiO3 ceramics were investigated for their microstructure and dielectric characteristics. The powders were prepared by the conventional solid state procedure. The concentration of Sm2O3 as a donor dopant has been kept from 0.1 up to 5.0 at%. The content of MnO2 as acceptor was kept constant at 0.05 at% Mn in all samples. The specimens were sintered at 1290 °C, 1320 °C and 1350 °C in an air atmosphere for two hours.A mainly uniform and homogeneous microstructure with average grain size ranging from 0.3 µm to 2.0 µm was observed in low doped samples. In highly doped samples, apart from the fine grained matrix, the appearance of local area with secondary abnormal grains was observed.The dielectric properties were investigated as a function of frequency and temperature. The low doped samples exhibit the high value of dielectric permittivity at room temperature and the greatest change at the Curie temperature. The highest value of dielectric constant (εr=6800) was measured for 0.1Sm/BaTiO3 samples sintered at 1350 °C. A nearly flat permittivity-temperature response and lower values of εr were obtained in specimens with 2.0 and 5.0 at% additive content. The dielectric constant increases with the increase of sintering temperature. The dissipation factor ranged from 0.01 to 0.22 and decreases with the increase of sintering temperature. The Curie constant (C), Curie-Weiss temperature (T0) and critical exponent of nonlinearity (γ ) were calculated using a Curie-Weiss and modified Curie-Weiss law. The highest value of Curie constant (C=9.06·105 K) was measured in 0.1 at% doped samples. The Curie constant decreased with increasing dopant content. The γ values, ranging from 1.001 to 1.58, point out the sharp phase transition in low doped samples, and the diffuse phase transition in heavily doped BaTiO3 samples. 相似文献
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Isabel Santacruz Jon Binner Maria I. Nieto Rodrigo Moreno 《International Journal of Applied Ceramic Technology》2010,7(Z1):E135-E143
The zeta potential and the rheological behavior of aqueous suspensions of a commercial nanosized BaTiO3 powder were studied. The influence of the volume fraction of solids, the kind and concentration of dispersant, the homogenization technique, and times were investigated. Because the as-received powder contained ∼5 wt% organics, the powder was calcined to 350°C/0.5 h. After calcination, a good dispersion was achieved for suspensions with up to 80 wt% solids using a polyacrylic-based dispersant combined with tetramethylammonium hydroxide and 10 min of ultrasound. Green bodies obtained by slip casting had relatively low densities (2.6 g/cm3, 43% TD), but homogeneous, agglomerate-free microstructures. 相似文献
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Ye Zhao Qian Wang Jun-Hu Lv Xian Zhao Chun-Ming Wang 《Ceramics International》2021,47(13):18610-18618
The electrocaloric effect (ECE) is a promising candidate to replace the vapor-compression cooling technology, which has reached its end of improving the energy utilization efficiency. In the present work, the Y-modified BaTiO3 ceramics with nominal compositions of Ba(Ti1-xYx)O3 (abbreviated as BT-100xY, where x = 0.0125, 0.025, 0.0375, 0.050 and 0.0625) have been prepared through the conventional solid-state reaction sintering method. The dielectric properties and electrocaloric effect of BT-100xY ceramics have been investigated in detail. The XRD patterns indicate that all the BT-100xY ceramics possess pure perovskite structure without secondary phases. The temperature dependence of dielectric permittivity reveals that the BT-1.25Y, 2.5Y, 3.75Y and 5.0Y are normal ferroelectrics, and the BT-6.25Y is a relaxor ferroelectric. The ECE is calculated through the indirect equation based on Maxwell relation. The BT-2.5Y exhibits the largest ΔT = 1.26 K and the largest ΔS = 1.68 J/kg · K among all the BT-100xY ceramics, and the BT-2.5Y also exhibits the largest ΔT/ΔE = 0.296 × 10?6 K · m/V and the largest ΔS/ΔE = 0.394 × 10?6 J · m/kg · K?V. The ECE in our work is comparable with or even larger than that of BaTiO3-based ceramics previously reported, which indicates that the BT-100xY ceramics are promising ECE materials. 相似文献
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Highly concentrated BaTiO3 suspensions in benzaldehyde were investigated for adaptation toward tape casting. Effects of particle concentration, total particle mass, gravitational forces, and particle size distribution on sediment density were studied. 相似文献
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Hironori Hatono Tomokazu Ito Kengo Iwata Jun Akedo 《International Journal of Applied Ceramic Technology》2006,3(6):419-427
Aerosol deposition (AD) is applicable as a fabrication technology for microstructures comprising different materials. We used this method for electronic devices that consist of ceramic films and metal electrodes. Various ceramic thick films (5–50 μm thickness), for example, Al2 O3 , 2MgO·SiO2 , and BaTiO3 , were deposited on substrates using room-temperature aerosol deposition. The dielectric constant of BaTiO3 was 78 at 1 MHz. Multilayer constructions with ceramic films and copper electrodes were obtained using aerosol deposition and sputtering. During deposition, photoresist film masks were applied to produce patterns of ceramic films and connections between upper and lower electrodes through the ceramic films. 相似文献
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受功能梯度材料设计理念的启发,采用聚合物微纳层叠共挤装置,提出了交替多层介电复合材料的假设,设计了(聚偏氟乙烯/钛酸钡)(PVDF/BaTiO3)/PVDF交替多层介电复合材料,研究了复合材料的结构和性能。结果表明,复合材料中PVDF以α、β两种晶型共存;随着BaTiO3含量的增加,体系的结晶度逐渐降低;介电常数先增大后减小,在BaTiO3质量分数为7.5%时,介电常数达到最大61.43 F/m(25℃,1 MHz);介电损耗因数先减小后增大,但介电损耗因数都小于0.1。因此,利用微纳多层共挤技术,设计的交替多层介电复合材料满足要求。 相似文献
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Dy2O3和La2O3掺杂对BaTiO3铁电陶瓷介电特性的影响 总被引:16,自引:0,他引:16
对BaTiO3和BaTiO3-Co2O3系组成进行了Dy2O3和La2O3稀土改性的研究,考察了该系统的介电温度特性和耐电性能,观察了样品的显微结构,讨论了Dy2O3和Dy2O3和La2O3在改变BaTiO3铁电温谱特性的作用,结果表明:Dy2O3和La2O3的掺杂效果存在差异,Dy2O3掺杂明显促进BaTiO3细晶化,而La2O3掺杂呈现出对BaTiO3基介质材料的Curie峰更强的压峰和移峰效应,在BaTiO3-Nb2O5-Co2O3-Dy2O3系统中可获取高介高压特性瓷料,其介电常数≈3000,tgδ<1.5%,介电温谱符合“X7R”标准,击穿强度可达7-8kV/mm。 相似文献
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S. Sipahioğlu S. Madakbaş L. Arda K. Esmer 《Journal of Inorganic and Organometallic Polymers and Materials》2013,23(2):333-339
Barium titanium oxide/polyaniline (BaTiO3/PANI) nano-composites were obtained in two different processes by the use of PANI and BaTiO3 nano-particles synthesized by the sol–gel technique. FT-IR, XRD, SEM and TGA measurements were taken for structural properties of all samples. The molecular interaction between BaTiO3 nanoparticles and PANI was between the H atoms in the N–H bond and the OH molecules in the solution environment. The said interaction was coordinated with BaTiO3 molecules over O atoms. XRD results confirmed that the synthesized BaTiO3 had a characteristic cubic perovskite structure and that its structure had not changed. TGA results revealed that the composites became more stable as the BaTiO3 amount increased. The dielectric measurement results are consistent with the structural results at higher frequencies. Dielectricity increased as BaTiO3 ratio increased in the environment. The change in the real part of the dielectric permittivity by frequency was stable at high frequencies. According to these results, it is concluded that the composite samples could have very high electromagnetic wave absorption values at higher frequencies (GHz). 相似文献