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Modeling of crystal growth in heteroepitaxial systems
摘要： This paper investigates the elastic deformation of the structure containing InAs nanoclusters in a pyramid, grown on the substrate GaAs. So far the data have not been grown quantum dots (QDs), one of the reasons is significant difference of periods, which reaches 7%. Ideally atomic plane on the border of QDs and substrate must continuously sews. Due to the difference in lattice periods crosslinking occurring deformations and mechanical stresses, the magnitude of which is proportional to the number of atomic planes, the size of base of the pyramid. Therefore, when you reach a certain size islands (quantum dots), they may experience mechanical stresses sufficient for the appearance of structural defects - dislocations, fractures.
关键词： mechanical stresses,crystal growth,quantum dots,heteroepitaxial systems,elastic deformation
更新于2025-09-09 09:28:46
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Structural and optical properties of (Cu6PS5Br)1-(Cu7PS6) mixed crystals
摘要： The structure and optical properties of Bridgman-grown (Cu6PS5Br)1-x(Cu7PS6)x mixed crystals are reported. X-ray diffraction data reveal a face-centred cubic lattice (Fm-34 space group) for Cu6PS5Br-rich crystals (0<x<0.4) and a primitive cubic lattice (P213 space group) for Cu7PS6-rich (0.4<x<1) crystals. These structural data correlate with the Raman spectra where, besides the common features typical for the argyrodite-type Cu6PS5Br and Cu7PS6 crystals, weaker bands characteristic only for the end-point compounds are observed in the corresponding compositional intervals. Based on the spectral position of the short-wavelength edge of diffuse reflection spectra, the compositional dependence of the energy gap is studied exhibiting a nonlinear behaviour.
关键词： Inorganic materials,crystal growth,diffuse reflection,Raman scattering,X-ray diffraction,crystal structure
更新于2025-09-04 15:30:14
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Improved photocatalytic performance of flower-like BiOBr/BiOCl heterojuctions prepared by an ionic liquid assisted one-step hydrothermal method
摘要： Construction of heterojuctions is a promising and solid strategy to tune the photocatalytic performance of BiOCl. In this work, flower-like BiOBr/BiOCl heterojuctions (IL-BiOCl) was in-situ prepared by N-ethylpyridinium bromide ([BPy]Br) assisted one-step hydrothermal method. The samples were studied by a serials method. The results exhibit that [BPy]Br promotes the specific surface area and the separation rate of photoinduced carriers. Energy dispersive spectrometer (EDS) and high resolution transmission electron microscopy (HRTEM) results firmly reveal that BiOBr/BiOCl heterojuctions were successfully constructed. [BPy]Br provides Br source for BiOBr and influences the shape of the IL-BiOCl. Photocatalytic activity of the samples were evaluated, the results reveal that IL-BiOCl possesses higher photocatalytic activity than BiOCl toward decomposition of rhodamine B (RhB) under simulated sunlight irradiation.
关键词： Semiconductors,surfaces,crystal growth,ionic liquid,BiOCl
更新于2025-09-04 15:30:14
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Reference Module in Materials Science and Materials Engineering || SixGe1-x Bulk Crystals
摘要： Germanium–silicon (Ge1(cid:1)xSix) or silicon–germanium (SixGe1(cid:1)x) alloy, where x indicates the mole fraction of silicon, is a complete solid-solution semiconductor having the diamond cubic structure. The lattice parameters of the two elements differ by 4% and those of the solid solution closely follow Vegard's law from 0.564 (pure germanium) to 0.534 nm (pure silicon), while the bandgap changes from 0.72 (germanium) to 1.2 eV (silicon) according to composition. GeSi alloys are important for both microelectronic and optoelectronic devices and various functional materials because of the potential for bandgap and lattice parameter engineering they offer. The phase diagram of GeSi alloy is shown in Figure 1. The solidus and liquidus curves are widely separated. The equilibrium distribution coef?cient, k0 ? xs/xl (xs and xl being the solidus and liquidus concentration of silicon), is as large as 6 for germanium-rich solutions and about 2.2 at the average melting-point temperature of each element. Such a large gap between the liquidus and the solidus and the difference in the physical properties of the constituent elements, such as density, lattice parameter, and melting temperature, make the crystal growth of GeSi alloys very dif?cult. This article provides an outline of the applications and reviews the growth of bulk GeSi, discussing relevant problems, residual defects, impurities and dopants, and covers the structural properties of the alloys. The study of such alloys is also of interest from the fundamental view point of solidi?cation.
关键词： solid-solution semiconductor,crystal growth,microelectronic devices,optoelectronic devices,GeSi alloys
更新于2025-09-04 15:30:14
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Effects of n-butyl amine incorporation on the performance of perovskite light emitting diodes
摘要： The efficiency of perovskite light emitting diodes (PeLEDs) is crucially limited by leakage current and nonradiative recombination. Here we introduce n-butyl amine (BA) to modulate the growth of perovskite films as well as improve the performance of PeLEDs, and investigate in details the effects of BA incorporation on the structural, optical, and electrical characteristics of perovskite films. The results indicate that BA would terminate the grain surface and inhibit crystal growth, leading to increased radiative recombination. However, BA overload would make the films loose and recreate shunt paths. The electrical detriment of BA overload outweighs its optical benefit. As a result, optimal PeLEDs can be obtained only with moderate BA incorporation.
关键词： optical and electrical characteristics,butyl amine,crystal growth,bulky organic cations,perovskite light emitting diodes
更新于2025-09-04 15:30:14
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Synthesis, physicochemical and quantum chemical studies on a new organic NLO crystal: Cinnamoylproline
摘要： Cinnamoylproline was synthesized and the crystal was grown from solution by the slow evaporation method. The crystal belongs to the trigonal crystal system with non-centrosymmetric space group P31. The calculated geometry and experimental geometry from single crystal X-ray data were compared. Intermolecular interactions were studied using Hirshfeld surface analysis and its real space functions were calculated using Atoms In Molecules (AIM) and its isosurfaces were visualized using Non-covalent interaction analysis. Optical transparency of the crystal was analyzed by UV-Vis analysis and it was found that the crystal has good optical transparency in the visible range and the lower cut-off wavelength was found to be 326 nm. In the photoluminescence spectrum, a broad emission peak at 369 nm was observed. The functional groups were analyzed using FTIR techniques and the vibrational frequencies from experimental and theoretical values were compared. It was inferred from the TG-DTA studies that the crystal was thermally stable up to 375°C. Kurtz-Perry powder SHG analysis was also carried out with KDP as a reference. It showed that the crystal has 1.08 times greater efficiency than KDP. The first hyperpolarizability tensor of the molecule was calculated theoretically and theoretical second order susceptibility was obtained and compared with the experimental susceptibility.
关键词： Non Covalent Interaction (NCI),Crystal growth,Hirshfeld surface analysis,cinnamic acid,QTAIM,First hyperpolarizability
更新于2025-09-04 15:30:14
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Optical, dielectric properties and thermal analysis on sodium sulfanilate dihydrate nonlinear optical single crystal
摘要： Nonlinear optical sodium sulfanilate dihydrate (SSD) single crystal was grown by slow evaporation solution method at ambient temperature. Unit cell parameters were elucidated with the study of single crystal X-ray diffraction. Fourier transform infrared spectroscopic analyses were performed to indentify a variety of functional groups present in the grown SSD crystal. The level of optical transmittance of the grown SSD crystal was investigated by UV–Vis–NIR spectral analysis. The lower cut off wavelength of the grown crystal was observed at 243 nm and the band gap energy is found to be 5.23 eV. The spectral study of photoluminescence was carried out for the grown crystal which shows a sharp emission peak at 485 nm resulting blue–green emission that is suitable for the optical communication applications. Mechanical strength was measured by utilizing Vickers microhardness test and the value of n is found to be 2.25 asserting that the crystal belongs to soft material category. The dielectric properties were studied as a function of frequency at various temperatures and also the grown SSD crystal has been correlated with electro-optic properties. Thermogravimetric analysis was undertaken by a thermal analyzer with the temperature starting from 30 to 800 °C and TGA/DTA results show that the crystal has good thermal stability and useful for laser applications. Etching analysis also was performed for the grown SSD single crystal proving that it has good crystalline nature with fewer defects.
关键词： Thermal analysis,Sodium sulfanilate dihydrate,Nonlinear optical materials,Dielectric properties,Optical properties,Crystal growth
更新于2025-09-04 15:30:14
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Studies on growth and characterization of (E)-N′-[4-(dimethylamino) benzylidene]-4-hydroxybenzohydrazide hemihydrate: a nonlinear optical material
摘要： Hydrazone compound (E)-N′-[4-(dimethylamino) benzylidene]-4-hydroxybenzohydrazide hemihydrate (DMABHBH) was synthesized and single crystals of DMABHBH were grown by solvent evaporation method at room temperature. Molecular structure of DMABHBH compound was confirmed by 1H and 13C nuclear magnetic resonance techniques. The presence of functional groups was confirmed by Fourier transform infrared and FT Raman spectral analyses. The X-ray crystal structure was elucidated at 173 K by single crystal X-ray diffraction and the results were compared with the corresponding values obtained at 298 K. The compound crystallizes in the chiral monoclinic space group P21. Mechanical stability of the grown crystals was estimated from the Vicker’s microhardness test. Powder second harmonic generation efficiency of DMABHBH is about 1.1 times that of potassium dihydrogen phosphate. DMABHBH is found to show optical limiting behavior at high input light intensities, the third order nonlinear optical absorption coefficient measured using open aperture Z-scan studies, is 0.95 × 10?11 m/W. Anti-bacterial activity was studied using the well and disc diffusion methods.
关键词： X-ray diffraction,Mechanical properties,Nonlinear optical material,Thermal analysis,Antibacterial activity,Hydrazone,Crystal growth
更新于2025-09-04 15:30:14