- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
High infrared transmittance CdS single crystal grown by physical vapor transport
摘要： Φ55 × 15 mm2 CdS bulk single crystal with high infrared transmittance was grown by physical vapor transport. The single crystal has a consistent structure from top to bottom, which was confirmed by X-ray diffraction. The (002) full-width at half-maximum of the X-ray diffraction was measured to be 60.00 arcsec, indicating a good quality of the structure. Hall mobility, specific resistivity, and carrier concentration for the top and bottom of the crystal were observed as well. Transmittance for the CdS single crystal was measured to be higher than 70% from 2.5 to 4.5 μm, making the single crystal an important candidate for infrared window materials. Furthermore, the absorption mechanism of the CdS single crystal was analyzed.
关键词： physical vapor transport,X-ray diffraction,semiconducting materials,single crystal growth
更新于2025-09-23 15:23:52
-
Growth of perovskite nanocrystals in poly-tetra fluoroethylene based microsystem: On-line and off-line measurements
摘要： Cesium lead halide perovskite nanocrystals are photoelectric nanomaterials that have potential applications in a variety of areas due to their excellent photoelectric and tunable photo luminescent properties. In this work, we investigate the synergetic effects of reaction temperature, reaction-capillary length and flow rate on the growth kinetics of perovskite nanocrystals in PTFE-based microsystem and the photoluminescence characteristics of the synthesized nanocrystals both online and offline. The on-line measurement finds that increasing the reaction temperature leads to the increase of the wavelength of the PL emission peak of the nanocrystals synthesized at different reaction temperatures decreases with the increase of the flow rate. The off-line measurement reveals that increasing the flow rate generally leads to the blueshift of the PL emission peaks and the decrease of the average size of the perovskite nanocrystals synthesized at the reaction temperature of 160 oC in the capillary length of 60 cm. Increasing temperature leads to the increase of the emission wavelength of the perovskite nanocrystals from 560 nm to 608 nm. The temperature dependence of the average size of the synthesized nanocrystals with the same synthesis conditions at different temperatures can be described by the Arrhenius relationship with an activation energy of 8.54 kJ/mol. Five different cross-sections of the synthesized perovskite nanocrystals are observed, including rhombus, hexagon, rectangle, square and quadrangle with three of them being observed for the first time.
关键词： microreaction system,morphologies,growth kinetics,reaction parameters,perovskite nanocrystal
更新于2025-09-23 15:23:52
-
A novel growth strategy of TiO<sub>2</sub> anodic films using surface residual stress as driving force
摘要： The relationship between residual stress and growth behavior of anodic titanium oxide films (TiO2) was investigated in terms of defect chemistry and the nanocrystalline materials thermodynamic. The results showed that the surface residual stress can be controlled by acting on the duration of the surface mechanical attrition treatment (SMAT). When samples are processed by grinding for 30 min, the residual stress value reaches a maximum of 73.13 MPa, approximately 7.2 times higher than the one obtained with untreated sample. Under these conditions, the thickness of the anodic film was about 1200 nm, three times that of the TA2 anodic film. Furthermore, the results of electrochemical tests showed that following the surface mechanical attrition treatment, the anodic film show lower density vacancies, higher resistance to the diffusion of Cl-, higher density, and an improved corrosion resistance when compared to TA2. Generally speaking, the growth behavior of the anodic film can be improved by identifying the suitable residual stress.
关键词： Surface mechanical attrition treatment,Anodic oxidation,Corrosion resistance,Growth mechanism
更新于2025-09-23 15:23:52
-
Growth, optical, mechanical and thermal behavior of unidirectionally grown L-Glutaminium p-Toluenesulfonate crystal
摘要： Organic crystal of L-Glutaminium p-Toluenesulfonate (LGPT) was grown unidirectional by Sankaranarayanan and Ramasamy (SR) method. The grown crystal belongs to monoclinic crystal system with noncentrosymmetric space group P21. High resolution XRD confirms crystalline perfection of the grown crystal. Optical transmission shows that unidirectional grown crystal has higher transmittance and the lower cut-off wavelength is 290 nm. The emission wavelength of grown crystal is 410 nm and emission region is confirmed by luminescence spectra. The laser damage threshold value of unidirectional crystal has increased by 0.3 GW/cm2. The grown LGPT crystals belong to hard material category and it confirms the normal indentation size effect. The grown LGPT crystal is thermally stable upto 165 oC and decomposition of the molecules were elucidated by using TGA and DSC. Powder second harmonic generation measurement confirms the efficiency of the grown LGPT crystal is 0.8 times that of KDP.
关键词： Nonlinear optical materials,Crystal growth,Recrystallization,Optical properties
更新于2025-09-23 15:23:52
-
Structural and vibrational properties of PVT grown BiTeCl microcrystals
摘要： High-quality BiTeCl microcrystals are grown by the physical vapor transport (PVT) method without using a foreign transport agent. The plate-like microcrystals with a developed (0001) surface are up to ~500 μm in diameter. The grown crystal phase composition was identified by the X-ray single crystal structure analysis in space group P63mc: a = 4.2475(6) ?, c = 12.409(2) ?, Z = 2 (R = 0.0343). The BiTeCl microcrystal phase purity was verified by Raman microspectrometry under excitation at λ = 632.8 and 532.1 nm.
关键词： PVT crystal growth,crystal structure,topological insulator,SEM,BiTeCl,Raman spectroscopy
更新于2025-09-23 15:23:52
-
Hydrothermal synthesis of tellurium nanorods by using recovered tellurium from waste electronic devices
摘要： Tellurium (Te) nanostructures with controlled morphology have received considerable attention in various applications owing to tunable optic, thermoelectric, photoelectronic, piezoelectric, and electrochemical properties. Herein, we introduce the cost-effective and eco-friendly synthesis of Te nanorods (Te NRs) from end of life electronic devices via hydrothermal methods. The Te NRs show the average diameter of 44.6 nm and a length of 358 nm in presence of polyvinylpyrrolidone, as a stabilizing agent. Moreover, the bismuth and intact p-type semiconductor (i.e., Bi0.5Sb1.5Te3) are selectively recovered as intermediated products. The Te NRs exhibit the NO2 gas sensing properties with concentration as low as 1 ppm at room temperature and fast response/recovery times of 1.59 and 2.10 s at 1 ppm, respectively. We believe that this powerful approach can be expanded to not only selective recovery of valuable materials but synthesis of various nanomaterials from waste electronic devices.
关键词： Recycling,Grain growth,Chemical properties,Powders: chemical preparation,Sensors
更新于2025-09-23 15:23:52
-
Thermal analysis and crystal growth of doped Nb2O5
摘要： The systems Nb2O5–Ta2O5 and Nb2O5–V2O5 were investigated using thermal analysis, X-ray powder diffraction and thermodynamic simulations. Solid solution formation is possible for both systems; furthermore, both contain one intermediate compound, VNb9O25 or Ta2Nb4O15, respectively. Phase relationships for pure niobium(V)-oxide and tantalum(V)-oxide were studied under ambient pressure. It was found that both compounds can occur in two stable solid modifications. For niobium(V)-oxide this are the monoclinic high-temperature modification (H-Nb2O5) and an orthorhombic low-temperature modification (T-Nb2O5) and for tantalum(V)-oxide a tetragonal high-temperature form (α-Ta2O5) and an orthorhombic low-temperature form (β-Ta2O5). Based on these results, crystal growth experiments with various compositions from both systems were carried out using the optical floating zone (OZF) technique.
关键词： B2. dielectric materials,A2. growth from melt,A1. doping,A1. phase diagrams,B1. niobates
更新于2025-09-23 15:23:52
-
[IEEE 2018 IEEE International Conference on Manipulation, Manufacturing and Measurement on the Nanoscale (3M-NANO) - Hangzhou, China (2018.8.13-2018.8.17)] 2018 IEEE International Conference on Manipulation, Manufacturing and Measurement on the Nanoscale (3M-NANO) - Growth and Optical Properties of ZnSe Nanofilms Obtained from Modified Ammonia-free Chemical Bath Solution
摘要： ZnSe nano thin films were obtained with chemical bath deposition in an modified aqueous alkaline solution in which ammonia was eliminated complexing agent in our present work. The as-deposited films are transparent, specula reflective and homogenous. Energy-dispersive X-ray spectroscopy indicated that films were in near stiochiometric Zn:Se ratio. Measured by spectroscopic ellipsometry, thickness of 50~370nm film can be obtained, the ZnSe were in nano-films, morphology and the film formation process discussion indicated that the film grow through nano-cluster by nano-cluster deposition rather than ion by ion mechanism. Absorption of the annealed films in visible light area indicated that bandgap is around 2.8eV for the annealed ZnSe film obtained from modified ammonia free solutions, corresponding to the standard band gap for bulk ZnSe materials.
关键词： Growth Kinetics,ZnSe Films,Optical Properties,Chemical Bath solution
更新于2025-09-23 15:23:52
-
Hetero-Orientation Epitaxial Growth of TiO2 Splats on Polycrystalline TiO2 Substrate
摘要： In the present study, the effect of titania (TiO2) substrate grain size and orientation on the epitaxial growth of TiO2 splat was investigated. Interestingly, the splat presented comparable grain size with that of substrate, indicating the hereditary feature of grain size. In addition, hetero- and homo-orientation epitaxial growth was observed at deposition temperatures below 400 °C and above 500 °C, respectively. The preferential growth of high-energy (001) face was also observed at low deposition temperatures (≤ 400 °C), which was found to result from dynamic nonequilibrium effect during the thermal spray deposition. Moreover, thermal spray deposition paves the way for a new approach to prepare high-energy (001) facets of TiO2 crystals.
关键词： hetero-orientation epitaxial growth,preferential growth,crystal morphology,homo-orientation epitaxial growth,deposition temperature,hereditary feature
更新于2025-09-23 15:22:29
-
Homogeneous Large-area Quasi-freestanding Monolayer and Bilayer Graphene on SiC
摘要： In this study, we first show that the argon flow during epitaxial graphene growth is an important parameter to control the quality of the buffer and the graphene layer. Atomic force microscopy (AFM) and low-energy electron diffraction (LEED) measurements reveal that the decomposition of the SiC substrate strongly depends on the Ar mass flow rate while pressure and temperature are kept constant. Our data are interpreted by a model based on the competition of the SiC decomposition rate, controlled by the Ar flow, with a uniform graphene buffer layer formation under the equilibrium process at the SiC surface. The proper choice of a set of growth parameters allows the growth of defect-free, ultra-smooth and coherent graphene-free buffer layer and bilayer-free monolayer graphene sheets which can be transformed into large-area high-quality quasi-freestanding monolayer and bilayer graphene by hydrogen intercalation. AFM, scanning tunneling microscopy, Raman spectroscopy and electronic transport measurements underline the excellent homogeneity of the resulting quasi-freestanding layers. Electronic transport measurements in four-point probe configuration reveal a homogeneous low resistance anisotropy on both μm- and mm scales.
关键词： SiC terrace steps,polymer assisted sublimation growth,Epitaxial graphene,freestanding bilayer graphene,argon gas flow,graphene buffer layer,monolayer graphene,resistance anisotropy,large-scale graphene growth,freestanding monolayer graphene
更新于2025-09-23 15:22:29