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Direct in situ observation of electric field assisted densification of ZnO by energy dispersive X-ray diffraction
摘要： Electric field assisted sintering techniques are used to enhance the densification process, reducing sintering time and temperature. Here, we report the in situ characterization of non-isothermal densification behavior of zinc oxide under simultaneous application of thermal and electric field by energy dispersive X-ray diffraction. 99% density was achieved under the electric field of 50 V/mm in the 588–843 °C range in a short time without grain growth. The in-situ energy dispersive X-ray diffraction study revealed the abnormal volumetric unit cell expansion of 0.9% at 843 °C associated with the observed sudden rise of the power absorption by the specimen during densification. Moreover, the variation in peak broadening as a function of time exhibited singularity in the 588–843 °C range implying the formation and rearrangement of defects correlated with densification during electric field assisted sintering.
关键词： Sintering,ZnO,Flash,in situ diffraction
更新于2025-09-23 15:22:29
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Structure and properties of layered perovskites Ba1-Ln Fe1-Co O3-δ (Ln = Pr, Sm, Gd)
摘要： A series of samples of overall composition Ba1-xLnxFe1-yCoyO3-δ (Ln = Pr, Sm, Gd) with x = 0.3-0.4; y = 0-0.5 were prepared by glycerin nitrate technique in air. The crystal structure of single-phase Ba1-xLnxFe1-yCoyO3-δ (Ln = Pr, Sm, Gd) determined by XRD was described as cubic (sp. gr. Pm3(cid:1)m). However, transmission electronic microscopy revealed that both Sm- and Gd-doped oxides possess tetragonal structure with 5-fold and 3-fold increased c parameter respectively. Oxygen content in the complex oxides has been determined in air over wide temperature range by means of thermogravimetry and iodometric titration. The change in oxygen content with temperature for the phases with five-layered ordering was significantly smaller than for the disordered phases.
关键词： oxygen nonstoichiometry,X-ray diffraction,oxide materials,transmission electron microscopy,crystal structure
更新于2025-09-23 15:22:29
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Fabrication of AlN templates on SiC substrates by sputtering-deposition and high-temperature annealing
摘要： High-quality AlN templates fabricated by sputtering-deposition and post-deposition high-temperature annealing have great potential for deep ultraviolet light-emitting device applications. In this work, we fabricated AlN films on 6H-SiC substrates by sputtering and face-to-face annealing and characterized the structural quality of the AlN films before and after annealing. As reported in previous studies, to accomplish high-quality AlN films on SiC substrates using conventional methods, such as molecular beam epitaxy or metalorganic vapor phase epitaxy (MOVPE), it is important to grow the AlN on the SiC coherently. However, in this work, although the annealed AlN films were fully relaxed from the SiC substrates, or even had tensile strain, the AlN films indicated high crystallinity. The X-ray rocking curve full width at half maximum (XRC-FWHM) values of the 200-nm-thick annealed AlN film were 17 and 246 arcsec for the AlN (0002) and (10–12) diffraction, respectively. Though the annealed AlN film indicated rough surfaces with bunched step structures, the surface morphology was remarkably improved by MOVPE growth and clear atomic step-and-terrace structures were formed. The XRC-FWHM values of the MOVPE-grown AlN were 90 and 239 arcsec for the AlN (0002) and (10–12) diffraction, respectively.
关键词： A1. Stresses,A1. Atomic force microscopy,B1. Nitrides,B2. Semiconducting III-V materials,A1. X-ray diffraction
更新于2025-09-23 15:22:29
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Constructing CH <sub/>3</sub> NH <sub/>3</sub> PbI <sub/>3</sub> and CH <sub/>3</sub> NH <sub/>3</sub> PbBr <sub/>3</sub> Perovskite Thin Film Electronic Structure from Single Crystal Band Structure Measurements
摘要： Photovoltaic cells based on halide perovskites and possessing remarkably high power conversion efficiencies have been reported. To push the development of such devices further, a comprehensive and reliable understanding of their electronic properties is essential, but presently not available. To provide a solid foundation for understanding the electronic properties of polycrystalline thin films, we employ single crystal band structure data from angle-resolved photoemission measurements. For two prototypical perovskites (CH3NH3PbBr3 and CH3NH3PbI3) we reveal the band dispersion in two high symmetry directions, and identify the global valence band maxima. With these benchmark data, we construct 'standard' photoemission spectra from polycrystalline thin film samples and resolve challenges discussed in the literature of determining the valence band onset with high reliability. Within the framework laid out here, the consistency of relating the energy level alignment in perovskite-based photovoltaic and optoelectronic devices with their functional parameters is substantially enhanced.
关键词： single crystal and thin film perovskites,angle-resolved photoemission,low-energy electron diffraction and density functional theory
更新于2025-09-23 15:22:29
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Additional phase transition in a PbZr <sub/>0.87</sub> Ti <sub/>0.13</sub> O <sub/>3</sub> single crystal
摘要： PbZr1-xTixO3 (PZT) ceramics are one of the most known and widely used piezoelectric materials. In order to understand the origin of the high piezoelectricity it is essential to also understand its phase diagram. Many recent papers reported on the modification of PZT phase diagram based on ceramic experimental data. This is due to difficulties to get good quality single crystal samples. We have succeeded in getting a good quality single crystal with x= 0.13. Based on temperature changes of elastic properties we confirmed the existence of additional phase transition appearing in the PbZr0.87Ti0.13O3. The temperature dependence of the elastic properties was investigated by means of piezoelectric measurements and Brillouin light scattering. We discussed the correlation between anomalies of the elastic properties found in these measurements, and suggested that, except for the two well-known phase transitions, these anomalies point to another phase transition below Tc. The structure and symmetry of this crystal have been tested with use of the x-ray diffraction at the room temperature.
关键词： x-ray diffraction,phase transitions,elastic properties,piezoelectricity,PZT single crystals
更新于2025-09-23 15:22:29
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[IEEE 2018 IEEE International Conference on Computational Electromagnetics (ICCEM) - Chengdu (2018.3.26-2018.3.28)] 2018 IEEE International Conference on Computational Electromagnetics (ICCEM) - Monostatic GTD Model for Double Scattering due to Specular Reflections or Edge Diffractions
摘要： GTD model is a good candidate to extract the features of radar targets, which describes the frequency dependence of scattering centers for many geometries or mechanisms and can represent the attribute information of the geometrical structures. The mechanisms associated with this model have been proven to include single reflection, single diffraction and multiple reflections from dihedral and trihedral corner reflectors. However, multi-scattering mechanisms from more complex structures are not studied adequately. In this paper, we expand the GTD model to any double scattering due to specular reflections or edge diffractions, and derive the related frequency-dependence factor. Finally, a simulation validates the theory.
关键词： specular reflection,multiple scattering mechanism,frequency-dependence factor,flat surface,straight edge,doubly-curved surface,GTD model,curved edge,edge diffraction,singly-curved surface
更新于2025-09-23 15:22:29
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Specific Features of the Molecular Structure of A New 3-(Benzo[d]Oxazole-2-Yl)- 1-(2-(1,3,3-Trimethylindoline-2-Ylidene) Ethylidene)Naphthalene-2(1H)-One Zinc Chloride Complex
摘要： X-ray diffraction is used to determine the structure of a new 3-(benzo[d]oxazole-2-yl)-1-(2-(1,3,3-trimethylindoline-2-ylidene)ethylidene)naphthalene-2(1H)-one zinc chloride complex 1. It is demonstrated that the ligand molecule in complex 1 has a trans–trans–cis conformation in which the indoline nitrogen atom is oriented in the same direction as the chelate ring, which could promote an additional coordination with the complexing atom.
关键词： 3-trimethylindoline-2-ylidene)ethylidene)naphthalene-2(1H)-one zinc chloride,3,3-(benzo[d]oxazole-2-yl)-1-(2-(1,spiropyrans,X-ray diffraction study
更新于2025-09-23 15:22:29
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[IEEE 2017 International Renewable and Sustainable Energy Conference (IRSEC) - Tangier (2017.12.4-2017.12.7)] 2017 International Renewable and Sustainable Energy Conference (IRSEC) - Mapping of the Composition of Soils Naturally Deposited on PV Modules Anywhere in Morocco
摘要： This article constitutes a preliminary phase for the performance of a national cartography of the composition of soils naturally deposited on photovoltaic modules installed in sites of different climates. To do this, a climatic zoning of Morocco according to the De Martonne index was adopted in order to select representative sites concerned with the collection of samples. For the moment, four samples have been collected in Rabat, Errachidia, Agadir and Oujda. These samples were prepared and analyzed. Several analyzes were carried out to determine the physical, chemical and mineralogical composition of these samples. The mineralogical composition was determined via X-Ray Diffraction (XRD) and X-Ray Fluorescence analysis (XF), while characterization of the physical and chemical composition was identified using Differential Scanning Calorimetry (DSC) and Spectroscopy Infrared (IR). The results show the existence of the same abundant constituents namely: Quartz, Calcite, Dolomite, Kaolinite whose percentages differ from a climate to another.
关键词： Soils,Quartz,Calcite,Differential Scanning Calorimetry (DSC),Kaolinite,Climatic zoning,Infrared spectroscopy (IR),X-Ray Diffraction,Photovoltaic modules,Dolomite,Cartography,X-Ray Fluorescence
更新于2025-09-23 15:22:29
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Correlation Between Currents, X-ray Diffraction Patterns and Transfer Characteristics of SnO <sub/>2</sub> Thin Film Transistor
摘要： SnO2 thin film transistor (TFT) was prepared with SiOC as a gate insulator on n-type Si and the correlation between bonding structures, the contact properties of SnO2 thin films and the transfer characteristics of TFTs was researched. The current of SnO2 thin films increased with increasing the crystallinity and the crystallinity of SnO2 was increased by annealing. The SnO2 deposited with much oxygen gas flows became an amorphous structure after annealing due to lowered crystallinity. On the other hand, the current decreased in the amorphous structure SnO2 with high oxygen vacancies. However, the ambipolar transfer characteristics of SnO2/SiOC TFT with an amorphous structure had higher stability-mobility than that of TFT with the crystallinity, because of the increment effect of the diffusion current at the depletion layer as the amorphous structure with high Schottky barrier (SB).
关键词： Amorphous Structure,SnO2,Capacitance,TFT,X-ray Diffraction
更新于2025-09-23 15:22:29
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Synthesis and Properties of Novel Thiophene-Based Liquid Crystalline Conducting Polymers
摘要： Side-chain liquid crystalline polythiophenes were synthesised and the effects of the mesogenic units on the structure and electronic properties of the polymers were studied. The liquid crystal properties of the polymer films were studied using polarised hot-stage optical microscopy and differential scanning calorimetry, and X-ray diffractometry was used to investigate the effect of a magnetic field on the monomers and polymers.
关键词： Polythiophene,Conducting polymers,Liquid crystals,X-ray diffraction,Magnetic field
更新于2025-09-23 15:22:29