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排序方式: 共有2597条查询结果,搜索用时 375 毫秒
1.
AbstractBa0.95Ca0.05Ti1-xZrxO3 (BCTZO) ceramics were prepared by a solid state reaction method. The samples were characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM) and X-ray absorption near edge structure (XANES). The ceramics exhibit a pure perovskite structure. The average grain size gradually decreases with increasing Zr concentration. XANES results indicate that the intensities of pre-edge peaks dropped with increasing Zr concentration. The BCTZO ceramic of x?=?0.05 has the optimum electrical properties with the maximum dielectric constant (ε'm), remanent polarization (2Pr), coercive electric field (2Ec) and piezoelectric charge constant (d33) of 7,244, 12.54 (μC/cm2), 5.29 (kV/cm) and 288 (pC/N), respectively. 相似文献
2.
《Ceramics International》2022,48(13):18278-18285
We report the improved energy storage density and efficiency after 2.5% of Samarium substitution in ferroelectric Pb[(Mg1/3Nb2/3)0.80Ti0.20]O3 (PMNT) electroceramic. The microstructure and surface morphology were analyzed and correlated with various functional properties. The energy storage density, leakage current density, ferroelectric and dielectric properties were investigated thoroughly, indicating that Samarium's substitution significantly modified the microstructure, the dielectric strength, breakdown electric field, and turned ferroelectric PMNT to relaxor ferroelectrics. Due to the relaxor nature, the gap between remanent polarization and maximum polarization increases with the substitution of Samarium in PMNT matrix, which further increases the recoverable energy storage density and energy efficiency. A nearly 100% increase in recoverable energy density and efficiency was obtained at an electric field strength of 35 kV/cm at room temperature (~296 K). The electroceramic shows maximum energy density near the ferroelectric phase transition temperature (325 K–345 K) region and provides a moderate energy storage density for possible applications in power microelectronics. 相似文献
3.
Previous studies indicate that the properties of graphene oxide (GO) can be significantly improved by enhancing its graphitic domain size through thermal diffusion and clustering of functional groups. Remarkably, this transition takes place below the decomposition temperature of the functional groups and thus allows fine tuning of graphitic domains without compromising with the functionality of GO. By studying the transformation of GO under mild thermal treatment, we directly observe this size enhancement of graphitic domains from originally ≤40 nm2 to >200 nm2 through an extensive transmission electron microscopy (TEM) study. Additionally, we confirm the integrity of the functional groups during this process by a comprehensive chemical analysis. A closer look into the process confirms the theoretical predicted relevance for the room temperature stability of GO and the development of the composition of functional groups is explained with reaction pathways from theoretical calculations. We further investigate the influence of enlarged graphitic domains on the hydration behaviour of GO and the catalytic performance of single atom catalysts supported by GO. Additionally, we show that the sheet resistance of GO is reduced by several orders of magnitude during the mild thermal annealing process. 相似文献
4.
Yang Yang Yibei Zhou Juan Ren Qiaoji Zheng Kwok Ho Lam Dunmin Lin 《Journal of the European Ceramic Society》2018,38(2):557-566
Perovskite ferroelectrics possess the fascinating piezoelectric properties near a morphotropic phase boundary, attributing to a low energy barrier that the results in structural instability and easy polarization rotation. In this work, a new lead-free system of (1-x)BaTiO3-xCaHfO3 was designed, and characterized by a coexistence of ferroelectric rhombohedral-orthorhombic-tetragonal (R-O-T) phases. With the increase amount of CaHfO3 (x), a stable coexistence region of three ferroelectric phases (R-O-T) exists at 0.06 ≤ x ≤ 0.08. Both large piezoelectric coefficient (d33~400 pC/N), inverse piezoelectric coefficient (d33*~547 pm/V) and planar electromechanical coupling factor (kp~58.2%) can be achieved for the composition with x = 0.08 near the coexistence of three ferroelectric phases. Our results show that the materials with the composition located at a region where the three ferroelectric R-O-T phases coexist would have the lowest energy barrier and thus greatly promote the polarization rotation, resulting in a strong piezoelectric response. 相似文献
5.
铁电存储器的研究进展 总被引:1,自引:1,他引:0
介绍了铁电存储器的存储原理,同时对两种铁电存储器(铁电随机存取存储器和铁电场效应晶体管存储器)的研究进展、当前存在的问题以及我国目前在这一领域的研究现状进行了简单介绍,并对今后的技术发展进行了展望。 相似文献
6.
We present our machine learning system, that uses inductive logic programming techniques to learn how to identify transmembrane
domains from amino acid sequences. Our system facilitates the use of operators such as ‘contains’, that act on entire sequences,
rather than on individual elements of a sequence. The prediction accuracy of our new system is around 93%, and this compares
favourably with earlier results.
This work was carried out with the support of a research grant from ISIS, Fujitsu Laboratories. 相似文献
7.
形状记忆聚氨酯的结构与性能研究 总被引:1,自引:0,他引:1
以 2 ,4 -甲苯二异氰酸酯 (2 ,4 -TDI)、不同分子量的聚己二酸丁二醇酯 (PBAG)和 1,4-丁二醇 (BDO)为原料合成了具有形状记忆功能的聚氨酯材料。通过DSC、弯曲实验和力学实验 ,研究了形状记忆聚氨酯的性能 ,发现软段高度结晶和硬段聚集形成硬段微区是其具有较好形状记忆性能的必要条件。 相似文献
8.
L. V. El’nikova 《Journal of Superconductivity and Novel Magnetism》2007,20(2):197-199
We describe the lyotropic liquid crystalline phase transitions in the lipid mixture dipalmitoil-PC/dilauroy-PC/cholesterol
by 3D spin-1 lattice model. The formation of nanoscale domains with the characteristic size about 300 nm was studied in experiments
on confocal fluorescence microscopy (CFM) (G. V. Feigenson and J. T. Buboltz, Biophys. J.
80, 2775 (2001)). The structure parameters of the lamellar vesicle in dipalmitoil-PC-rich phase, corresponding to these regions,
are verified by numerical Monte Carlo simulations on the lattice. We point its superconductivity analogy properties at the
region of phase stability for composition-dependent nanoscopic region. 相似文献
9.
X7R弛豫复相铁电陶瓷的研究 总被引:1,自引:0,他引:1
以PZN-BT(低温相)、PMN-PT(高温相)为起始组元,采用混合烧结法制备了具有X7R介电特性电子瓷料,其介电温谱在55~+125℃范围内相当平坦,室温相对介电常数高达3 877,并从离子的键型分析了影响介电温度稳定性的原因,初步探讨了提高介电温度稳定性的机制。 相似文献
10.
纤维素酶分子的计算机辅助序列分析 总被引:3,自引:0,他引:3
利用生物大分子数据库(EMBL、SWALL和PDB)及软件技术(DNASIS和AntheProt)对嗜热子囊菌(Thermoascus aurantiacus)的产生的一种纤维素酶分子进行了序列分析及结构预测;通过多种来源的纤维素酶的比较研究,分析了其催化区、活性位点及局部保守序列。 相似文献