Crystal Research and Technology最新文献

Ultrapure gallium up to 99.9999%/ 99.99999% (6N/7N) purity level is a highly demanding material needed for the growth of gallium-based group III–V semiconductor compounds and optoelectronic devices. However, general extraction of gallium from Bayer liquor contains high impurity content and ultra-purification of the same cannot be accomplished by a single step. Thus, the purpose of this review is to assess various purification processes for the production of ultra-pure gallium and to critically examine its applications in the optoelectronics industry. Through this research survey, it is found that zone refining of the zone melting process stands tall over other methods in purifying materials even up to 13N. Hence, scientists are adopting detailed mathematical models and simulation tools for designing unique zone refining systems for material purification. Current-day technology even adopts intelligence methods such as machine learning, which sheds light on the importance of different zone refining parameters that influence the purification process. Here, the practical aspects of zone refining and how the feedback from the theoretical models or performance prediction through intelligence methods can be effectively incorporated into practice have also been emphasized

The full potential linearized augmented plane wave (FP-LAPW) method is used to compute structural, electronic, and optical properties of III-V semiconductor ternary alloys GaP_1-xSb_x (0≤x≤1) using first-principle calculations within density functional theory. To calculate the ground state parameters of the structure, the energy exchange-correlation Wu-cohen generalized gradient approximation is employed in the wiek2k program. The Tran–Blaha-modified Becke–Johnson (TB-mBJ) pseudopotential is employed in addition to the Wu-Cohen generalised gradient approximation to achieve a precise bandgap. After this, WC-mBJ is used to examine optical properties such as real and imaginary parts of the dielectric constant, and energy loss. This study illustrates the nonlinear dependency on the various Sb compositions by examining the composition impacts on the bandgap, bulk modulus, and lattice constant. Using WC-mBJ, the estimated band structures for alloys GaP_0.75Sb_0.25, GaP_0.50Sb_0.50, and GaP_0.25Sb_0.75 show direct energy bandgaps of 2.008 eV (617 nm), 1.482 eV (836 nm), and 1.055 eV (1174 nm), respectively. As a result, this material system has enormous potential for use in applications spanning the visible to infrared spectrum.

Magnesium and sulfate are a determinant key in CaCO₃ mineralization. However, the works of the literature have failed to provide a clear understanding of how these ions influence the nucleation-growth of CaCO₃ precipitation. Our study uses an electrochemical method, having for principle to impose a dissolved oxygen reduction potential on gold (111) films. This technique that allows the exclusive and controlled crystallization of epitaxial calcite established an ideal system for the study of foreign ions influence. The polymorph, composition and morphology of crystals are characterized using scanning electron microscopy (SEM) coupled with X-ray energy dispersive spectroscopy (EDS) and Raman spectroscopy. The results demonstrate that the increase of calcium concentration in calcocarbonic pure solution enhances the nucleation and then the growth of calcite crystals without affecting their morphology and their orientation. However, the magnesium directly modifies the surface morphology of calcite as a consequence of Mg substitution to calcium ions and the inhibitive effect of magnesium is assured by an incorporation mechanism. In the matter of sulfate ions influence, the experimental results indicate that SO₄²⁻ slows down the epitaxial calcite nucleation by substituting itself to carbonate ions preferentially in the center of the crystals facets causing an enlargement of the lattice parameter.

Due to the sensitivity of the electronic structure of semi-metals to small distortions of the crystal lattice, the study of the electrical and galvanomagnetic properties of bismuth films requires taking into account the deformation that occurs in the film-substrate system due to the difference in the thermal expansion of the film and substrate materials. The magnitude of these deformations plays an important role in analyzing the temperature dependencies of the transport properties of charge carriers. The paper presents an experimental study of the magnitude of deformation of bismuth films on various substrates at 300 and 77 K using X-ray diffraction. Changes in the lattice constant $�c$ of crystallites, the trigonal axis of which is perpendicular to the film plane, depending on the substrate material, are obtained. A comparison between the assessment of the deformation of these crystallites in the film plane based on Hooke's law and the difference in the coefficients thermal expansion of the film and substrate materials is made.

Cover image provided courtesy of Jianguang Zhou, Research Center for Analytical Instrumentation, Institute of Cyber-Systems and Control, State Key Laboratory of Industrial Control Technology, Zhejiang University, China.

Exploring new haloplumbate hybrids and understanding the structure-activity relationships are of great significance for further promoting their applications in the photovoltaic fields. Herein, with the in situ-formed [Hmd]⁺ (md = 2-methyl-1,3-diazinane) templates, a new organic–inorganic hybrid iodoplumbate, namely [Hmd]PbI₃ (1), is successfully constructed and then structurally characterized using multiple technical approaches. X-ray crystallography studies show that compound 1 features the typical 1D chain-like motifs of [Pb₂I₆]_n²ⁿ⁻, generating the 3D supermolecular network by the extensive hydrogen bond interactions. Interestingly, compound 1 exhibits the semiconductive behavior, with an optical band gap of 2.72 eV. More attractively, the title compound has good photoelectric switching performances under the alternating light irradiation, whose photocurrent densities compete well with or surpass those of many metal halide counterparts. Further theoretical analyses reveal that the title compound has a more dispersive band structure (especially the value band) that facilitates the transport of charge carriers, which may be the main origin of its excellent optoelectronic performance. Presented in this paper also bring the studies of Hirshfeld surface, X-ray photoelectron spectroscopy (XPS) as well as thermogravimetric analysis.

The development of eco-friendly, high-efficiency polyoxometalates (POMs) catalysts is vital for advancing catalytic oxidation and electrochemical detection in environmental protection. Herein, a POM-based Cu^II-containing complex with the molecular formula [H(4-AP)]₈[Cu₂(H₂O)₄(P₂Mo₅O₂₃)₂]·8H₂O (1) (4-AP = 4-aminopyridine) is synthesized using the hydrothermal method, and the crystal structure is determined by single X-ray diffraction (SXRD), infrared (IR) spectroscopy, and powder X-ray diffraction (PXRD). Structurally, complex 1 exhibits a one dimension (1D) chain arrangement, composed of Cu^II ions and Strandberg-type (P₂Mo₅O₂₃)⁶⁻ anionic clusters. These 1D chains are further interconnected through [H(4-AP)]⁺ ligands, resulting in the formation of a two dimension (2D) supramolecular network. Complex 1 serves as an outstanding heterogeneous catalyst for the oxidation of methyl phenyl sulfide (MPS), demonstrating a remarkable conversion rate of 99% for MPS and a selectivity of 98% toward methyl phenyl sulfoxide (MPSO). In addition to its catalytic capabilities, complex 1 is also employed in the electrochemical detection of Fe^III and Cr^VI ions, with low limits of detection (LODs) at 4.92 µm for Fe^III and 7.82 µM for Cr^VI.

As a biodegradable and biocompatible polymer material, polyglycolic acid is attracting more and more attention in the field of polymeric and biomedical materials. Consequently, the study of the transformation between different crystal forms of glycolide, the monomer of polyglycolic acid, is of great importance, because crystal forms of glycolide determine the stabilities and properties of polyglycolic acid products polymerized under different conditions in industry. Herein, this article reports the synthesis and crystallization of α- and β-glycolide controlled by the type of organic solvents and/or temperatures, during which an intermediate crystal form of β′-glycolide is newly observed. The transformation between α-, β-, and β′-glycolide is investigated in detail, and the stabilities of different crystal forms are illustrated via the controlled experiments under different relative humidity (RH) as well as the theoretical calculations, which should provide fundamental concepts and guidance for the industrial production of glycolide and optimization of polyglycolic acid products.

Direct InN growth is demonstrated and characterized on a sapphire (Al₂O₃) substrate by plasma-enhanced metal–organic chemical vapor deposition using high-density nitrogen (N₂) microstrip-line microwave plasma. N₂ plasma irradiation at 650 °C for 20 min forms AlN on Al₂O₃ substrate. No peak regarding metallic In droplets is detected from InN/Al₂O₃ regardless of N₂ plasma irradiation. InN is found to be rotated 30° with their a-axis oriented to become $��\left[��10�\overline{1}�0��\right]�$ InN // $��\left[��11�\overline{2}�0��\right]�$ Al₂O₃. The transition layers are confirmed at the InN/Al₂O₃ interface regardless of N₂ plasma irradiation. The surface of InN consisted of large undulations with root mean square values >30 nm, suggesting that strain relaxation introduces misfit dislocations.