Metallurgical and Materials Transactions A - We have examined spheroidization and coarsening of cementite in an initially pearlitic 2C-4Cr ultrahigh carbon steel containing a cementite network.... 相似文献
An insurmountable disadvantage of CuInSe2 is the low band gap, which limits the open-circuit voltage to value well below 500 mV in solar cells. The incorporation of sulfur into CuInSe2 thin film was investigated to establish a scientific basis for the graded band gap CuIn(Se1 − x,Sx)2 thin films. CuIn(Se1 − x,Sx)2 thin films were obtained by reactive annealing of Cu11In9 precursors in a mixture of sulfur and selenium atmosphere while post-sulfurization of single phase CuInSe2 did not result in CuIn(Se1 − x,Sx)2 thin films. A band gap of 1.36 eV, was obtained for the prepared CuIn(Se1 − x,Sx)2. 相似文献
β-In2S3 films were grown on glass as well as on quartz substrates by rapid heating of metallic indium films in H2S atmosphere. The effect of sulfurization temperature and time on the growth, structural, electrical and photoelectrical properties of β-In2S3 films has been investigated. Highly oriented single-phase β-In2S3 films were grown by the sulfurization technique. The morphology and composition of films have been characterized. The optical band gap of β-In2S3 is found to vary from 1.9 to 2.5 eV when the sulfurization temperature is varied from 300 to 600 °C or by increasing the sulfurization time. The electrical properties of the thin films have also been studied; they have n-type electrical conductivity. The photoelectrical properties of the β-In2S3 films are also found to depend on the sulfurizing temperature. A high photoresponse is obtained for films prepared at a sulfurizing temperature of 600 °C. β-In2S3 can be used as an alternative to toxic CdS as a window layer in photovoltaic technology. 相似文献
In today’s highly computerized society, detection and recognition of text present in natural scene images is complex and difficult to be properly recognized by human vision. Most of the existing algorithms and models mainly focus on detection and recognition of text from still images. Many of the recent machine translation systems are built using the Encoder-Decoder framework which works on the format of encoding the sequence of input and then based on the encoded input, the output is decoded. Both the encoder and the decoder use an attention mechanism as an interface, making the model complex. Aiming at this situation, an alternative method for recognition of texts from videos is proposed. The proposed approach is based on a single Two-Dimensional Convolutional Neural Network (2D CNN). An algorithm for extracting features from an image called the crosswise feature extraction is also proposed. The proposed model is tested and shows that crosswise feature extraction gives better recognition accuracy by requiring a lesser period of time for training than the conventional feature extraction technique used by CNN.
Linearly polarized emission has been observed from a crystalline one-dimensional (1D) microstructure fabricated from N,N′-dioctyl-3,4,9,10-perylenedicarboximide (PTCDI-C8) molecules via solution phase self-assembly. Rotating microscopy imaging of a 1D microstructure under crossed polarization was performed for the investigation of polarized emission. The anisotropy birefringence was maximum only when the 1D microstructure was aligned 45° to the direction of the polarizer and it was minimum when aligned parallel to the polarizer implying that the transmission axis of the 1D microstructure is perpendicular to its π–π stacking direction. A model has been proposed to explain linearly polarized emission from the microstructure. 相似文献
Electron channelling contrast imaging of threading dislocations in GaN (0002) substrates and epitaxial films has been demonstrated using a conventional polepiece-mounted backscatter detector in a commercial scanning electron microscope. The influence of accelerating voltage and diffraction vector on contrast features denoting specific threading dislocation types has been studied. As confirmed by coordinated transmission electron microscopy analysis, electron channelling contrast imaging contrast features for edge-type threading dislocations are spatially smaller than mixed-type threading dislocations in GaN. This ability to delineate GaN edge threading dislocations from mixed type was also confirmed by defect-selective etch processing using molten MgO/KOH. This study validates electron channelling contrast imaging as a nondestructive and widely accessible method for spatially mapping and identifying dislocations in GaN with wider applicability for other single-crystal materials. 相似文献
Electron channeling contrast imaging (ECCI) using a conventional pole-mounted backscatter detector in a commercial scanning
electron microscope (SEM) has been implemented to analyze extended defects. In-grown extended defects in bulk SrTiO3 (001) substrates such as dislocation loops, subsurface dislocations parallel to the surface, and surface-penetrating dislocations
have been distinguished by ECCI. The techniques of dislocation-selective etching and ECCI have been compared side-by-side,
where surface-penetrating dislocations have been shown to have one-to-one correspondence with ECCI spot features. g·b and g·b × u have been implemented for subsurface portions of intrinsic dislocations, being identified as screw dislocations with Burgers
vector in the 〈100〉 direction. 相似文献
In this study, two different melting methods were used to investigate effects of Nb modification on microstructure in ultrahigh carbon steel (UHCS). Nb-free and Nb-modified UHCS samples were produced by melting and resolidifying an industrially produced base UHCS with and without addition of Nb powder. Microstructure was characterized using scanning electron microscopy, X-ray diffraction, and electron dispersive spectroscopy. Equilibrium computations of phase fractions and compositions were utilized to help describe microstructural changes caused by the Nb additions. Nb combined with C to form NbC structures before and during austenite solidification, reducing the effective amount of carbon available for the other phases. Cementite network spacing in the Nb-free samples was controlled by the cooling rate during solidification (faster cooling led to a more refined network). Network spacing in the Nb-modified UHCS could be enlarged by NbC structures that formed cooperatively with austenite. 相似文献
A comparative study of AlGaN/GaN high-electron-mobility transistor (HEMT) surface passivation using ex situ and in situ deposited SiNx is presented. Performing ex situ SiNx passivation increased the reverse gate leakage and off-state channel leakage by about three orders of magnitude. The in situ SiNx layer was characterized using transmission electron microscopy (TEM) and capacitance–voltage (CV) measurements. Photoluminescence
(PL) spectra indicated a reduction of nonradiative recombination centers in in situ SiNx-passivated samples, indicating improved crystal quality. CV measurements indicated a reduction of surface state density as
well, and thus better overall passivation using in situ SiNx. Electroluminescence (EL) images of the channel regions in AlGaN/GaN HEMT devices operating in forward blocking mode with
up to 400 V drain bias demonstrated reduced channel emission profiles of in situ-passivated devices. Compared with a nonpassivated reference sample, the reduced EL emission profiles correlated with a reduced
channel temperature on ex situ SiNx-passivated devices. 相似文献
Transmission electron microscopy with in situ biasing has been performed on TiN/single‐crystal rutile TiO2/Pt resistive switching structures. Three elementary processes essential for switching: i) creation of oxygen vacancies by electrochemical reactions at low temperatures (<150 °C), ii) their drift in the electric field, and iii) their coalescence into planar faults (and dissociation from them) have been documented. The faults have a form of vacancy discs in {110} and {121} planes, are bound by partial dislocation loops, and are identical to Wadsley defects observed in nonstoichiometric TiO2 annealed at high temperatures. The faults can be regarded as a precursor to the formation of oxygen‐deficient Magnéli phases, but 3D secondary phase inclusions have not been detected. Together, the observations shed light on the behavior of oxygen vacancies in relatively low electric fields and temperatures, suggesting that, in addition to the rather accepted notion of oxygen vacancy motion during the writing processes in resistive switching devices, such motion may occur even during reading, and may be accompanied by significant oxygen vacancy creation at modest device excitation levels. 相似文献