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《Ceramics International》2022,48(17):24439-24453
Lead-free multiferroic 3–0 type particulate composites with a composition (1?x)(Ba0.85Ca0.15Zr0.1Ti0.9O3) – x(Ni0.7Zn0.3Fe2O4) [(1?x)BCZT – xNZFO with 0 ≤ x ≤ 100 at%] were prepared using solid state reaction method. Structural and microstructural analysis using XRD, FESEM and Raman techniques confirmed the phase formation of the ferroelectric (BCZT) and magnetostrictive (NZFO) phases without any detectable presence of impurity phases. Rietveld refinement of the XRD data revealed a tetragonal (P4mm) and a cubic structure (Fdm) for the BCZT and NZFO phases, respectively. Elemental compositions of the constituent phases were assessed by EDS and XPS analyses. Electrical, magnetic, and magnetoelectric (ME) measurements were performed. The composites exhibit typical well-saturated magnetic hysteresis (M?H) loops at room temperature, having very low coercive field () values, indicating their soft ferromagnetic behavior. Various parameters extracted from the M?H curves including , magneto-crystalline anisotropy, squareness, and magnetization were found to depend on x. Frequency dependence of capacitance and admittance exhibited a resonance behavior corresponding to the radial mode of the electromechanical resonance (EMR). ME coefficients were studied in both longitudinal () and transverse () modes. The highest coupling coefficients, ~14.5 mV/Oe.cm and ~13 mV/Oe.cm were obtained for composite with 50 at% NZF at off-resonance frequency of 1 kHz. At the EMR frequency of 314 kHz, the value in 0.5BCZT-0.5NZFO composite enhanced enormously to ~5.5 V/Oe.cm. The studies conclude that x = 0.5 is an optimum atomic fraction of NZFO in the particulate composite for maximum ME coupling. 相似文献
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Marina G. Shelyapina Denis Y. Nefedov Artem V. Kostromin Oleg I. Silyukov Irina A. Zvereva 《Ceramics International》2019,45(5):5788-5795
To study protons localization in H1.83K0.17La2Ti3O10·0.17H2O and their motional characteristics, complementary Nuclear Magnetic Resonance (NMR) techniques have been applied. 1H Magic Angle Spinning NMR evidences the presence of different proton containing species. By analyzing the temperature dependence of the 1H MAS NMR spectrum we attribute the observed lines to interlayer H+ in regular sites (isolated and in water rich environment), water protons and protons from various defects. The temperature behaviors of the spectral lines intensities and widths point out that intercalated water molecules are involved in translational motion that is confirmed by spin lattice relaxation rate () and spin-lattice relaxation rate in rotating frame () measurements. It has been shown that for a correct determination of the proton motional parameters the Kohlrausch-Williams-Watts correlation function must be used. Its application results in the following parameters of proton motion in the interlayer space of H1.83K0.17La2Ti3O10·0.17H2O: ?=?0.194(2) eV, ?=?0.28(1), ?s. 相似文献
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Jing Ge Weixin Li Lei Zhao Yuxuan Li Xuan He Wei Fang Hui Chen Fuqing Zhang 《Ceramics International》2019,45(3):3715-3722
A novel three dimensional (3D) cellular network structured film is developed for CdS/CdSe quantum dots sensitized solar cells (QDSSCs). The vertically net-connected hollow photoanode is synthesized via a stepwise hydrothermal method. Benefiting from the hierarchical architecture, the specific surface area is dramatically enhanced thus allowing for loading more quantum dots. Besides, the optical characteristic results demonstrate that the light scattering ability is improved which could be ascribed to the easily trapped incident light in the cellular net-connected . Furthermore, the one dimensional (1D) structure inherited from nanorods arrays provides direct channels for electron transport accompanied with less recombination. The measured power conversion efficiency (PCE) of the QDSSCs based on this cellular photoanode is 4.54%, which is 2.2 times higher than that of the QDSSCs based on the original nanorods photoanode. The enhanced photovoltaic performance is ascribed to the higher light harvesting efficiency, improved light scattering property and promoted electron transport. The net-connected photoanode with 1D structure could offer the design of tailored architecture targeting various solar cells. 相似文献
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Peixin Qiao Youfeng Zhang Xuefeng Chen Mingxing Zhou Genshui Wang Xianlin Dong 《Ceramics International》2019,45(6):7114-7119
Currently, there is an urgent need of extraordinary comprehensive pyroelectric materials for the wide application in detectors and energy harvesters. In this study, the (Pb1–1.5xLax)(Zr0.86Ti0.14)O3 (abbreviated as PLZT, x?=?0.02, 0.03, 0.04 and 0.05) ceramics located in ferroelectric-antiferroelectric (FE-AFE) phase boundary were designed and synthesized by using conventional solid-state reaction method. The microstructures, phase structures, dielectric, ferroelectric, thermal depolarization and pyroelectric properties of the PLZT ceramics with different La content were investigated thoroughly. The XRD results show that the PLZT ceramics change from FE phase to AFE phase with increasing La content. The significant improvement of pyroelectric coefficient and figures of merit (FOMs) are achieved in the PLZT ceramics with the increase in La content because of the increased metastable ferroelectric phase under the application of electric field. The (Pb0.955La0.03)(Zr0.86Ti0.14)O3 (x?=?0.03) ceramic exhibits not only high of and high depolarization temperature (Td) of 179?℃ but also excellent FOMs with , , and . In addition, the highest of is achieved in (Pb0.94La0.04)(Zr0.86Ti0.14)O3 (x?=?0.04) ceramic. These results demonstrate that the PLZT ceramics of x?=?0.03 and 0.04 are promising candidates for pyroelectric applications. 相似文献
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《Ceramics International》2022,48(15):21221-21234
In this work, the Pechini method was used to synthesize - type perovskites, evaluating the effect of the type of cation and composition on the structural, morphological and textural properties. The use of similar rare earth cations was studied to promote weak bonds between the reactive surface and adsorbed oxygen species that could facilitate the oxygen reduction reaction and thus improve electrochemical performance of SOFC devices. To achieve this goal, different compositions of Pr or Sm ions (x = 0.1, 0.3, 0.5 or 0.6) were used for the partial substitution of lanthanum at the A site. The results indicated that the substitution of La by Pr or Sm did not modify the original orthorhombic perovskite structure of Ca-doped lanthanum manganites. However, a shift in the main reflections can be obtained as the content of both cations increases due to cell distortion. Rietveld refinement confirms that the crystal structure belongs to the Pnma space group with a large distortion along the b-axis but no secondary phase formation. The compensated charge neutrality of the Mn3+/Mn4+ ratio influences the octahedral sites of MnO6 and cell volume. Orthorhombic distortion () occurs through Jahn-Teller mechanism promoting a hole-doped system for electrical conductivity. The adsorption-desorption isotherms reveal that in any composition of Pr, a mesoporous isotherm (type IV) is obtained. In contrast, the isotherms changed from micro- to meso-porous features depending on the amount of Sm substitution at the A-site. All the prepared samples showed a soft granular structure with agglomerates ranging between 200 and 300 nm with well-interconnected pores. Comparing the La substitution by Pr or Sm, it was found that Sm can form perovskites that can better promote oxygen vacancies and triple boundary phase formation, which is essential in SOFC devices. 相似文献
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polycrystalline nanoparticles with various compositions and were prepared using sol–gel techniques, for which zinc acetate dihydrate and erbium 2–4 pentanedionate are used as precursors. Nanoparticles were pressed under a pressure of ?tons for ?min into disk-shaped compacts with 2?mm thicknesses and 10?mm diameters. The pressed samples were annealed at 400?°C for ?min. X-ray diffraction (XRD), scanning electron microscopy (SEM), and Vickers microhardness analyses of the produced Er-doped bulk nanomaterials were performed. Specifically, in this study we focused on the analysis of their mechanical properties. Undoped and Er-doped bulk samples were investigated according to Meyer's law; the proportional sample resistance (PSR), elastic/plastic deformation (EPD), and indentation-induced cracking (IIC) models; and the Hays–Kendal (HK) approach. As a result, the IIC model was more suitable to determine the micromechanical properties and the reverse indentation size effect () behavior of Er-doped semiconductors. 相似文献
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Jiří Čapek Šárka Batková Stanislav Haviar Jiří Houška Radomír Čerstvý Petr Zeman 《Ceramics International》2019,45(7):9454-9461
High power impulse magnetron sputtering of a Ta target in various gas mixtures was utilized to prepare amorphous tantalum oxynitride (Ta–O–N) films with a finely controlled elemental composition in a wide range. We investigate the effect of film annealing at in vacuum on structure and properties of the films. We show that the finely tuned elemental composition in combination with the annealing enables the preparation of crystalline Ta–O–N films exhibiting a single TaON phase with a monoclinic lattice structure, refractive index of and extinction coefficient of (both at the wavelength of ), optical band gap width of (suitable for visible light absorption up to ), low electrical resistivity of (indicating enhanced charge transport in the material as compared to the as-deposited counterpart), and appropriate alignment of the band gap with respect to the redox potentials for water splitting. These films are therefore promising candidates for application as visible-light-driven photocatalysts for water splitting. 相似文献