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Preferred orientation of 2,7-dioctyl[1]benzothieno[3,2- <i>b</i> ][1]benzothiophene molecules on inorganic single-crystal substrates with various orientations
摘要： The organic molecule 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene (C8-BTBT) was deposited on quartz glass, e11 (cid:2)20T A-, (0001) C-, and e1 (cid:2)102T R-single-crystal Al2O3 (sapphire), and (100)-, and (111)-single-crystal MgO substrates by vacuum thermal evaporation, and structural characterizations were carried out by X-ray di?raction analysis and atomic force microscopy (AFM) observation. The (001) out-of-plane orientation with a similar in-plane orientation was obtained irrespective of the substrate material and orientation, and its formation was governed by π–π-stacking-induced molecular ordering. The degree of orientation was re?ected by the grain structure related to the substrate material. The growth model of the oriented C8-BTBT layer was speculated on the basis of experimental results.
关键词： π–π-stacking,vacuum thermal evaporation,X-ray diffraction,C8-BTBT,atomic force microscopy
更新于2025-09-23 15:21:21
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Structural, Electrical and Morphological Properties of Materials Type Sillenite Phase Bi12TiO20
摘要： This work reports the investigation of the ternary system Bi2O3–TiO2–MgO. Some compositions have been synthesized by solid state reaction at 800?°C and characterized by powder X-ray diffraction. The doping of (α-Bi2O3) allowed us to stabilize three compositions isotype of sillenite structure phase with formulas Bi0.9 Ti0.1 O1.55, Bi0,9 Ti0,05Mg0,05 O1,5, and Bi0.8 Mg0.1 Ti0.1 O1.5. The structural resolution of the synthesized materials was performed using Rietveld method by means of FullProf program. It crystallizes in the cubic system. The space group I23 and lattice parameter a = 10.1723(2) ?. The morphological proprieties of the synthesized compositions have been investigated by means of scanning electron microscopy (SEM). Sintered samples showed a dense and uniform microstructure. The density of sintered samples obtained is nearly 92% of the theoretical density. Various impedance model including capacity and Warburg impedances have been used to interpret the Nyquist representations of electrical analyses. The highest conductivity is observed for Bi0.9 Ti0.1 O1.55 (σ = 1.39E?07 at 600?°C).
关键词： Electrical Impedance,SEM,Spectroscopy,X-ray diffraction,Sillenite
更新于2025-09-23 15:21:21
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A noticeable effect of thickness on third order nonlinear properties of CBD grown CdS thin films investigated by Z-scan measurements
摘要： In current work, thin films of CdS with alike thickness were fabricated by chemical bath deposition by varying the deposition time. Thickness of films was measured to be ~ 200, 250 and 300 nm using Alfa step stylus profilometer. As thickness play significant role hence thickness dependent structural, vibrational, morphological, optical and third order nonlinear optical (TONLO) studies are exclusively explored. The XRD and FT-Raman studies revealed an enhancement in crystallinity with increasing thickness of films and also confirmed non existence of any impurity peak. Crystallite size evaluated from Scherrer's rule is found to be increased from 21 to 30 nm with increasing the thickness of films. Scanning electron microscopy images demonstrates the modification of spherical nanoparticles to nano needles with increase of thickness of films. Average size of grains are intuited to be in 30 to 65 nm range. Transmission spectra showed high transparency for films of 200 nm thickness and later reduced with increase of thickness. Direct energy gap was attained in range of 2.2 to 2.3 eV. Stable values of k and n indicates defect free films. The n2 and χ3 values are found to very high which are in range of 3.15 to 8.67 (×10-6) and 1.11 to 1.47 (×10-1), respectively. Such transparent films with higher TONLO susceptibility values are potential candidates for optoelectronic device applications.
关键词： CdS films,FT-Raman spectroscopy,Optical properties,X-ray diffraction,third order nonlinear properties
更新于2025-09-23 15:21:21
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Study of materials structure physics of isomorphic LiNbO <sub/>3</sub> and LiTaO <sub/>3</sub> ferroelectrics by synchrotron radiation X-ray diffraction
摘要： Electron charge density studies of stoichiometric LiNbO3 and LiTaO3 ferroelectrics have been carried out by analyzing the synchrotron radiation X-ray powder di?raction data using a combination of the Rietveld and maximum entropy methods. The clear relationships between the Nb(Ta)–O bond length, the electron charge density on the Nb(Ta)–O bond, and the phase transition temperature TC are revealed for isomorphic structures. Nb(Ta)–O bonding plays an important role in the elevation of TC. The TC in LiNbO3 being higher than that in LiTaO3 is attributed to the larger lattice distortion of the Nb–O oxygen octahedron in LiNbO3. The validity of estimating TC for LiNbO3 family crystals from the degree of lattice distortion in the ferroelectric structure is discussed.
关键词： ferroelectric,LiTaO3,X-ray diffraction,synchrotron radiation,LiNbO3,phase transition temperature,electron charge density
更新于2025-09-23 15:21:21
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The effect of Zn3N2 phase decomposition on the properties of highly-doped ZnO: Al, N films
摘要： Study of Al-N simultaneous doping and thermal annealing influence on the properties of ZnO films is very important for achievement as p-type conductivity in the films as for improvement the performance of ZnO-based ultraviolet detectors. Highly-doped ZnO:Al,N films containing the Zn3N2 phase (ZnO:Al,N-Zn3N2) were grown on Si substrates by magnetron sputtering using a layer-by-layer growth technique. Our work presents a comparative study of the structure, optical and electronic properties of highly-doped as-grown and annealed ZnO:Al,N films. It was shown that the thermal annealing of ZnO:Al,N-Zn3N2 film at atmospheric conditions allows to decompose the Zn3N2 phase. The features of this phenomena on the properties of ZnO:Al,N films were investigated and discussed in detail by using X-ray diffraction, energy dispersive X-ray analysis, Raman scattering, photoluminescence, X-ray photoelectron spectroscopy and X-ray emission spectroscopy.
关键词： Radio-frequency magnetron sputtering,Zinc oxide,Nitrogen-aluminum doping,Photoluminescence,X-ray photoelectron spectroscopy,Thin films,X-ray diffraction,Raman scattering
更新于2025-09-23 15:21:01
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Thermal stability study of transition metal perovskite sulfides
摘要： Transition metal perovskite chalcogenides, a class of materials with rich tunability in functionalities, are gaining increased attention as candidate materials for renewable energy applications. Perovskite oxides are considered excellent n-type thermoelectric materials. Compared to oxide counterparts, we expect the chalcogenides to possess more favorable thermoelectric properties such as lower lattice thermal conductivity and smaller band gap, making them promising material candidates for high temperature thermoelectrics. Thus, it is necessary to study the thermal properties of these materials in detail, especially thermal stability, to evaluate their potential. In this work, we report the synthesis and thermal stability study of five compounds, a-SrZrS3, b-SrZrS3, BaZrS3, Ba2ZrS4, and Ba3Zr2S7. These materials cover several structural types including distorted perovskite, needle-like, and Ruddlesden–Popper phases. Differential scanning calorimeter and thermogravimetric analysis measurements were performed up to 1200 °C in air. Structural and chemical characterizations such as X-ray diffraction, Raman spectroscopy, and energy dispersive analytical X-ray spectroscopy were performed on all the samples before and after the heat treatment to understand the oxidation process. Our studies show that perovskite chalcogenides possess excellent thermal stability in air at least up to 550 °C.
关键词： differential scanning calorimeter,thermoelectric materials,Transition metal perovskite chalcogenides,thermal stability,thermogravimetric analysis,Raman spectroscopy,Ruddlesden–Popper phases,X-ray diffraction,energy dispersive analytical X-ray spectroscopy
更新于2025-09-23 15:21:01
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Growth of high purity zone-refined Boron Carbide single crystals by Laser Diode Floating Zone method
摘要： We report the growth of 4 mm diameter x 50 mm long Boron Carbide (B4C) with large single crystal regions using a Laser Diode Floating Zone (LDFZ) method at varying growth rates of 5-20 mm/hr. These materials were grown using polycrystalline B4C as a seed. Microstructural characterization shows the presence of a significant number of twinning-boundaries along the growth direction ([001]h) oriented in the (1210)h plane. At faster growth rates >10 mm/hr, the crystal orientation was reproducible, suggesting a twin-plane mediated growth mechanism. On the contrary, at slower growth rates <10 mm/hr the crystal orientation was not reproducible, suggesting a critical rate for twin-plane mediated growth to dominate. Zone refinement of these crystals led to a significant reduction of trace impurities to better than 99.999 wt % purity, at the expense of increased twinning. Powder x-ray diffraction confirms that the bulk is rhombohedral B4C, consistent with the microstructural analysis. The X-ray reciprocal space maps reveal the growth direction to be close to the [001]h direction, and the corresponding ω-rocking curve width is ~530arcsec. The rocking curve consisted of 3 distinct peaks, indicating in-plane mosaicism, consistent with the twinning observed. Berkovich nano-indentation of the key (001)h plane showed 41 ± 1 GPa hardness, with a Young’s modulus of 520 ± 14 GPa, comparable to literature reports.
关键词： A2. Single crystal growth,A1. Defects,A1. X-ray diffraction,A1. Characterization,A2. Growth from melt
更新于2025-09-23 15:21:01
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Growth and investigation on novel single crystal of ?2-cyclodextrin 2, 4-dinitrophenylhydrazine for optical sensors applications
摘要： Nonlinear optical (NLO) 2, 4-Dinitrophenylhydrazine (DNPH) single crystal was grown by slow evaporation solution growth method at ambient temperature. The characterization of Powder X – Ray diffraction peaks was con?rmed the new crystalline system. Fourier transform infrared spectroscopic analysis (FTIR) was used to the identi?cation of various functional groups present in the grown crystal. The range of optical transmittance exhibited by the grown bCD-DNPH crystal was investigated by UV Visible – NIR spectral analysis. The lower cut off wavelength of the grown crystal is observed at 270 nm. The SEM ?gures are recorded in different magni?cation. It is clear that the surface of the grown crystal appears very smooth although it has pots and microcrystal on the surface. The grain boundaries are clearly seen which shows the perfect growth of the crystal. The weight percentage (wt %) of C, N and O as obtained from EDAX analysis is in concurrent with the theoretical values. The SHG ef?ciency of the grown crystal was determined.
关键词： Optical properties,X-ray diffraction,Crystal growth
更新于2025-09-23 15:21:01
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Microstructure characteristics of non-monodisperse quantum dots: On the potential of transmission electron microscopy combined with X-ray diffraction
摘要： Although the concept of quantum confinement was introduced more than thirty years ago, a wide application of the quantum dots is still limited by the fact that monodisperse quantum dots with controlled optoelectronic properties are typically synthesized on a relatively small scale. Larger scale synthesis techniques are usually not able to produce monodisperse nanoparticles yet. In this contribution, we illustrate the capability of the combination of transmission electron microscopy and X-ray diffraction to reveal detailed and scale-bridging information about the complex microstructure of non-monodisperse quantum dots, which is the first step towards a further upscalling of the techniques for production of quantum dots with controlled properties. As a model system, CdSe quantum dots synthesized using an automated robotic hot-injection method at different temperatures were chosen. The combined microstructure analytics revealed the size and shape of the CdSe nanocrystals and the kind, density and arrangement of planar defects. The role of the planar defects in the particle coarsening by oriented attachment and the effect of the planar fault arrangement on the phase constitution, on the crystallographic coherence of the counterparts and on the optoelectronic properties are discussed.
关键词： microstructure,optoelectronic properties,planar defects,transmission electron microscopy,X-ray diffraction,quantum dots,oriented attachment,CdSe
更新于2025-09-23 15:21:01
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High Responsivity Visible Blind Pd/Al2O3/MoS2/ITO MISM UV Photodetector
摘要： In the present paper, Pd/Al2O3/MoS2/ITO MISM UV photodetector structure is proposed and analyzed. For the proposed photodetector, responsivity is 488 A/W, detectivity is 8.22×1013Jones and external quantum efficiency (EQE) is 1.9×105%, at wavelength 308nm, 1V bias and light intensity 13.6μW/cm2. Thus, proposed MISM photodetector device gives significant performance improvement over other UV photodetectors.
关键词： Molybdenum di-sulphide (MoS2),Responsivity,Photodetector,X-ray diffraction (XRD)
更新于2025-09-23 15:21:01