Papers by Keyword: Crystal Growth

Abstract: In this research we introduce an inexpensive method to produce highly crystalline GaN Nanowires (NWs) grown on porous zinc oxide (PZnO) using commercial GaN powder, either in argon gas or combination of nitrogen and Ar gas atmosphere, by thermal evaporation. Morphological structural studies using transmission electron microscope (TEM) and scanning electron microscopy (SEM) measurements showed the role of porosity and different gas flowing, in the alignment and nucleation of these NWs. The NWs grown under flow of mix gases have very different diameters of between 50 and 200 nm, but those which were grown in Ar gas atmosphere, have rather uniform diameter of around 50 nm. The length of the GaN NWs was uniform, (around 10 µm). Optical and structural characterizations were performed by energy-dispersive X-ray spectroscopy (EDX) and high resolution X-ray diffraction (HR-XRD). Results revealed that these NWs are of single-crystal hexagonal GaN with [oooı] and [ıoīı] growth directions for the NWs grown under Ar and mixed gas flow.

Abstract: Abstract. Recently, there has been increasting interest in the doping of nano-/microcrystal hosts with Sm³⁺. However, very few examples of Sm³⁺ doped YF₃ -based nanophosphors have been reported. In this paper, a variety of uniform YF₃:Sm nano-/microcrystals have been successfully prepared by a facile, effective, and environmentally friendly hydrothermal method. The morphology evolution process has been investigated by quenching the reaction at different time. Based on the results, a possible growth mechanism is presented in detail. The as-obtained YF₃:Sm nano-/microcrystals show strong yellow and red light emissions under room temperature, which is quite different from those reported previously and might find potential applications in fields such as light phosphor powers and advanced flat panel display devices.

Abstract: For the existing drawbacks in the crucible rotation vertical drop method, the control system is improved. Developed a new control system, overcome the drawbacks of original crystal growth control system, and improve the control precision, and simplify the programming program. Use to prove it reliable, stable, a more perfect crystal growth control system. Now has been formally put into use.

Abstract: Single crystals of lithium zinc titanate (Li₂ZnTi₃O₈) were grown in a double-mirror type optical floating-zone furnace for the first time. Single crystals were characterized by X-ray powder diffraction and Laue measurements. The ionic conductivity of the single crystals was measured in the temperature range of 400–700 K. Below 600 K, the ionic conductivity of the single crystal is one to two orders of magnitude higher than that of polycrystalline Li₂ZnTi₃O₈. In the temperature range of 550–600 K, the temperature dependence of the ionic conductivity shows non-Arrhenius behaviour.

Abstract: In this work, we investigate the effect of the N-doping on microstructure and electrical properties of chalcogenide Ge₂Sb₂Te₅ (GST) films for application to multilevel-storage phase change memory (PCM). Crystal size can be markedly reduced from 16 nm to 5 nm by N-doping into GST. The crystal growth suppression is believed to be controlled by distributed fine nitride particles. The resistivity of N-GST as a function of annealing temperature exhibits a gradual change due to the crystal growth suppression. The characteristics imply that N-GST is suitable for application to multilevel-storage PCM as the next-generation nonvolatile memory.

Abstract: This paper puts forward a simulation program of crystal growth, using TSSG method which is based on the finite element simulation technology. The core program FETSSG is developed on the basic of the finite element analysis software ANSYS. By using this program, we can simulate the process of crystal growth in all kinds of process conditions, and the numerical results include the single crystal furnace temperature field and fluid flow velocity field. These numerical results are in consistent with the laboratory results, which are valuable to the users.

Abstract: Electro Dynamic Gradient (EDG) method was utilized for TlBr crystal growth in this paper. The influence of crystal growth conditions such as temperature gradient and growth rate on optical and electrical properties of grown TlBr crystals was investigated. The quality of TlBr crystals was characterized by infrared (IR) transmittance spectrum, X-ray diffraction, and I-V measurements.

Abstract: For the existing drawbacks in the crucible rotation vertical drop method, the control system is improved. Developed a new control system, overcome the drawbacks of original crystal growth control system, and improve the control precision, and simplify the programming program. Use to prove it reliable, stable, a more perfect crystal growth control system. Now has been formally put into use.

Abstract: The aim of this work is to understand the early stages in the growth mechanism of invar (Fe64Ni34) alloys and also to study the influence of potential on the evolution of their crystalline structures. Fe64Ni34 layers were deposited onto copper substrates under optimal conditions using the electrochemical method of cyclic voltammetry (CV) and chronoamperometry (CA). The influence of the potential is examined and the nucleation kinetics is discussed. In this purpose, the obtained experimental data was interpreted by applying useful theoretical methods developed by Scharifker and Hills. X-ray diffraction experiments were performed on all samples in order to follow the structural evolution of Fe64Ni34 layers as a function of the potential.

Abstract: The experimental data present that primary silicon is precipitated from eutectic and hypoeutectic Al–Si alloy melts. It attributes to solute redistribution on the chemical driving force. Si atoms are easy to segregate to form Si-Si clusters, resulting in primary silicon precipitated from hypereutectic Al–Si alloy. Another reason is that primary silicon is precipitated from solid-liquid interface front once solute concentration in the solidification front exceeds eutectic composition. Solute redistribution equations are derivate from Jackson-Chalmers equation. The third reason is that precious little impurity turn Heterogeneous Nucleation of Si atoms.