Progress in Crystal Growth and Characterization of Materials最新文献

In this review article, we focus on the synthesis process and properties of Fe-Si-B-based soft magnetic alloys that exhibit superior magnetic properties. The process parameters related to the synthesis and characterization of these types of alloys are studied widely and investigated the properties observed in nanocrystalline Cu and Nb-dopped Fe-Si-B-based magnetic alloys. The properties of these materials are an exceptional combination of high permeability, high Curie temperature, low core losses and anisotropy energy, and near zero effective magnetostriction suitable for various applications such as magnetic field sensors, sensors for non-destructive evaluation of materials, motors, transformer cores, electric vehicles, etc. A significant number of research works have been conducted so far and more research is continued to improve their properties in various ways including engineering of materials composition, optimization of synthesis processes, and parameters for easy integration into modern devices. This review article aims to demonstrate a comparison study of the properties of Fe-Si-B- based soft magnetic alloys and to provide the latest updates on their developments toward tailoring the extrinsic (coercivity, and permeability) and intrinsic (Curie temperature and saturation magnetization) properties for conquering the subsequent area of applications.

Under alkaline conditions, silica forms self-assembled mineral compounds which are similar in morphology, nanostructure, and texture to the hybrid biomineral structures that, millions of years ago gave to life. In this review we propose that, during the earliest history of this planet, there was a geochemical scenario that led to large-scale production of both simple and complex organic compounds, many of which were important for prebiotic chemistry. The production was based on a high concentration of silica and high pH. Two main factors affected this process: a) a source of simple carbon molecules that were either synthesized abiotically from reactions associated with serpentinization, or carried by meteorites and produced by their impact on Earth, and b) the formation of self-organized silica-metal mineral compounds that catalyzed the condensation of single molecules in a reduced methane-rich atmosphere. We discuss the plausibility of this geochemical scenario and its catalytic properties and the transition towards a slightly alkaline to Neutral Ocean.

Step pattern stability of the vicinal surfaces during growth was analyzed using various surface kinetics models. It was shown that standard analysis of the vicinal surfaces provides no indication on the possible step coalescence and therefore could not be used to elucidate macrostep creation during growth. A scenario of the instability, leading go macrostep creation, was based on the dynamics of the step train, i.e. the step structure consisting of the high (train) and low (inter-train) density of the steps. The critical is step motion at the rear of the train which potentially leads to the step coalescence i.e. creation of the double and multiple step. The result of the analysis shows that the decisive factor for the step coalescence is the step density ratio in and out of the train. The ratio lower than 2 prevents double step formation irrespective of the kinetics. For higher ratio the coalesce depends on step kinetics: fast incorporation from lower terrace stabilizes the single steps, fast incorporation from upper leads to step coalescence. The double step is slower than the single steps, so the single steps behind catch up creating multistep and finally macrostep structure. The final surface structure consists of the macrosteps and superterraces, i.e. relatively flat vicinal segments. The macrostep alimentation from lower superterrace leads to emission of the single steps which move forward. Thus the single step motion is dominant crystal growth mode in the presence of the macrosteps. These steps finally are absorbed by the next macrostep. The absorption and emission of single steps sustain the macrostep existence, i.e. the macrostep fate is determined the single step dynamics. The condition for single step emission was derived. In addition, the macrosteps are prone to creation of the overhangs which results from surface dynamics coupling to impingement from the mother phase. The angular preferential access of the bulk material to the macrostep edge, leads to the overhang instability and creation of inclusions and dislocations.

This article highlights the electrodeposition of metals, in crystalline or amorphous form, that are monentous in the present era of science and technology. Available literature related to nucleation and growth of metal crystals has been reviewed to gain insight into the mechanism and kinetics. The progress made in the electrodeposition technique, using an ionic liquid (IL) medium, has been detailed for selected metals using different ILs for achieving the controlled growth mechanism driven by electrochemical potential. Theoretical models for nucleation and growth of crystals by electrodeposition have been explained and the effect of crystallization overpotential on the growth of crystal growth has been discussed. Finally, the factors affecting the growth process and the mechanism have been identified and critically analyzed based on the available literature, fundamental knowledge-base, chemistry of ILs, and electrodeposition.

The crystallization technique where an electric field is applied is an extremely powerful tool to control the crystallization processes of various materials. In particular, the method with application of an external electrostatic electric field can have a significant effect on the phase equilibrium of the liquid and solid phases. This review demonstrates that the crystallization processes of proteins are significantly impacted by the application of an external electrostatic electric field: (1) Control of both the increase and decrease in the nucleation rate can be achieved by changing the applied frequency of the external electrostatic electric field. (2) The effect of the external electrostatic electric field on the nucleation rate can be controlled by regulating the thickness of the electric double layer (EDL) formed at the interface. (3) The quality of the grown crystals can be improved by an increase in the step free energy under application of an external electrostatic electric field at 1 MHz. The effect of the external electrostatic electric field on nucleation and growth kinetics during crystal growth of proteins is also discussed based on a thermodynamic perspective.

Low dimensional structures, including bulk crystals, thin films, nanowires and nanotubes, have received remarkable attention due to their novel functionality and potential applications in various areas of optics, electronics, photonics, and sensing devices and photovoltaic field. Recently, remarkable progress and modification have been achieved in the synthesis process of crystalline material by vapor transport technique. In this review, we introduce an improved concept of the closed tube Chemical Vapor Transport (CVT) technique for the single crystal growth of ZrSTe, TiSTe and TiSeTe. A modified reverse temperature profile has reported the growth of ZrSTe, TiSTe and TiSeTe results show the good crystalline quality of synthesized materials. The single-crystal X-ray diffraction data reveals all three samples have trigonal unit cell structure with a space group of P31. The Semiconducting behavior of grown crystals of ZrSTe, TiSTe and TiSeTe was verified by two probe resistivity measurements, Hall Effect measurements and optical absorption at room temperature in the spectral range of 200 nm - 2200 nm. In this review, we highlight the recent progress in the transition of metal chalcogenides for their advanced application in solar energy conversion, thin-film electronics, optoelectronic devices and quantum communication devices. Moreover, different experimental challenges within the described growth technique are probed. Additionally, a survey was done for the possible enhancement of Transition Metal Chalcogenide (TMC) crystalline materials grown by the Chemical Vapor Transport technique based on various growth parameters.

As known currently, in the formation of the Earth, minerals have played a pivotal role going from the formation of the hydrosphere, the lithosphere, and all Earth components until the origin, evolution, and maintenance of life. The first signs of magnetism are found in komatiites. In the origin of life, minerals were responsible for concentrating, aligning, and acting as templates and catalyzers, allowing for the formation of bonds among the first biomolecules to form polymers, which eventually became assembled to give rise to the pioneer organism in the Precambrian. Besides, minerals allowed the DNA to be the information storing molecule, even though it was not the first biomolecule. Another function of minerals was to protect the organic complexes against ultraviolet radiation and hydrolysis, a fundamental action to preserve life in the Precambrian where high UV radiation prevailed. Minerals not only favored the origin of life but also became part of the organisms that inhabit the Earth, including species of the five kingdoms, comprising from microorganisms to higher organisms. How minerals participated in the origin of life still has unresolved questions, for which to understand the minerals’ participation since the formation of the Earth until becoming part of the structure of organisms from the five kingdoms, we reviewed the following topics, which will contribute to the understanding of the implication of minerals in the origin of our planet and life on it: i) the synthesis of the chemical elements from which the first mineral were obtained in the Earth, ii) the factor that favored the formation of minerals in the Earth, iii) the implication of minerals as the basis for the synthesis of the first biomolecule and, eventually, the pioneer organism, as well as the biomineralization mechanism that has been proposed to account for the mineral part contained in the structure of the organisms from the different kingdoms, and iv) the models that allow emulating the mechanisms by which minerals participated in the synthesis of the first biomolecule; in this way, for example, the Precambrian microfossils are so simple morphologically (spheres, subspheres, and hemispheres) that they can easily be imitated by hollow mineral growths, known as biomorphs. Although these can interfere with the study of actual microfossils, they remain as key points for the study of the origin of life.

This contribution deals with a practical overview of some popular and sophisticated crystallization methods that help increase the success rate of a crystallization project and introduces a newly developed method involving low intensity electromagnetic fields. Aiming to suggest a methodology to follow, the present contribution is divided into two main parts in a logical order to get the best crystals for high resolution X-ray crystallographic analysis. The first part starts with a short review of the chemical and physical fundamentals of each crystallization method through different strategies based on physicochemical approaches. Then, practical non-conventional techniques for protein crystallization are presented, not only for growing protein crystals, but also for controlling the size and number of crystals. These include crystal growth in gels, counter-diffusion, seeding, and macromolecular imprinted polymers (MIPs). The second part shows the effects of coupling low intensity electric fields (in the scale of units of  μAmperes) with weak magnetic fields (in the scale of milli Tesla) applied to protein crystallization. This approach consists of a novel experimental set up, which was used to study the influence of the coupled fields on the crystallization of lysozyme in solution and in gel media. This new approach is based on the classical theories of transport phenomena and offers a more accessible strategy to obtain suitable crystals for X-ray characterization or Neutron diffraction investigations.