Progress in Crystal Growth and Characterization of Materials最新文献

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.

Ice is one of the most abundant materials on the earth's surface, and its growth governs various natural phenomena. Hence, the molecular-level understanding of ice crystal surfaces is crucially important. However, it is generally acknowledged that the molecular-level observation of ice crystal surfaces by ordinary microscopy techniques, such as atomic force microscopy and scanning electron microscopy, is very difficult at temperatures near the melting point (0 °C). To overcome such difficulties, we have developed laser confocal microscopy combined with differential interference contrast microscopy (LCM-DIM). We proved that LCM-DIM can visualize individual elementary steps (0.37 nm in thickness) on a basal face by observing two-dimensional nucleation growth. Then we found by LCM-DIM that spiral steps on a basal face exhibit a double-spiral pattern, which can be expected from ice's crystallographic structure. In addition, we revealed that temperature dependence of growth kinetics of elementary spiral steps on a basal face exhibits complicated behaviors, which show the presence of unknown phenomena in the growth kinetics. Furthermore, we proved that surface diffusion of water admolecules on a basal face plays a crucially important role in the lateral growth of elementary steps when the distance between adjacent spiral steps is smaller than 15 µm. These findings will provide a clue for unlocking growth kinetics of ice crystals. In addition, through the use of LCM-DIM much progress has been made in studies on the surface melting of ice and the interaction between ice and atmospheric gasses.

In recent years, a series of investigations has been devoted to a possibility of using crystals based on CdTe with addition of magnesium (Mg), selenium (Se), or manganese (Mn) for X and gamma radiation detectors. In the literature there are contradictory data with respect to the segregation of Mg in (Cd,Mg)Te and Se in Cd(Te,Se) and to the possibility of obtaining materials with a homogeneous composition without grains and twins.

We have wide technological possibilities of preparing crystals and investigating some of their properties. Thus, we performed crystallizations of (Cd,Mg)Te, Cd(Te,Se), (Cd,Mn)(Te,Se), and (Cd,Mn)Te compounds. The aim of our studies was to check whether any of the investigated materials may be easily obtained by the Low Pressure Bridgman (LPB) method in the form of large, homogeneous, high resistivity single crystals with as few as possible twins, subgrains, and tellurium inclusions.

The crystallization processes were performed by using the LPB method. The elements used: Cd, Te, Mn, Mg, and Se were of the highest purity available at that time. In order to obtain reliable conclusions the crystallization processes were carried out under identical technological conditions. The details of our technological method and the results of the investigation of physical properties of the samples are presented below.

This review paper covers the low temperature wet growth of nano-engineered particles of ZnO-based mixed metal oxides, their growth mechanism, and characterization using X-ray diffraction, SEM, TEM and IR, UV–visible, and XPS spectral techniques. Main focus of this article is centered on low temperature semi-wet methods of synthesis that are suitable for large scale production of zinc oxide-based systems mixed with iron oxide, copper oxide, nickel oxide and cobalt oxide. These mixed metal oxides have broad industrial applications as catalyst, semiconductors, adsorbents, superconductors, electro-ceramics, and antifungal agents in addition to extensive applications in medicines. This paper discusses the low-cost and environment friendly synthesis of these mixed metal oxides, measurement of properties and applicability of these materials systems.

Molybdenum oxides (MoO_y) exhibit quite interesting structural, chemical, electrical, optical and electrochemical properties, which are often dependent on the synthetic procedures and fabrication conditions. The MoO_y materiails are promising in numerous current and emerging technological applications, which include nanoelectronics, optoelectronics, energy storage and micromechanics. However, fundamental understanding of the crystal structure and engineering the phase and microstructure is the key to achieving the desired properties and performance in all of these applications. Therefore, in this review, an attempt made to provide a comprehensive review by considering the illustrative examples to highlight the fundamental scientific issues, challenges, and opportunities as related to various Mo-oxides applicable to electrochemical energy applications. In the course of development of lithium batteries delivering high-power and high-energy density for powering electric vehicles, here in this paper, we examine the performances of Mo-oxides, which are candidates as electrodes materials primarily for lithium-ion batteries (LIBs), while some aspects considered in sodium-ion batteries (SIBs) or electrochemical supercapacitors (ECs). Due to the wide range of oxidation states (from +6 to +2) they are promising as both positive (cathode) and negative (anode) electrodes of electrochemical cells. Based on their specific structural, chemical, electrical, and optical properties, which are dependent on the growth conditions and the fabrication technique, this review highlights the progress made in improving and understanding the electrochemical performance of MoO_y compounds. Various materials (2.0 ≤ y ≤ 3.0) including anhydrous, hydrates, nanorods, nanobelts, composites and thin films of MoO_y are considered. Due to their higher oxidation states, MoO_y compounds undergo reversible topotactic lithium intercalation reactions; however, electrochemical features appear strongly dependent on the crystal quality and structural arrangement in the host lattice. Using in-situ and ex-situ X-ray diffraction and Raman spectroscopic data, structural characteristics of various MoO_y are discussed. While the reasons for first-cycle irreversible capacity losses identified and discussed elaborately, the approaches adopted for enhanced performance and/or improvements also summarized. Several sub-stoichiometric MoO_y positive electrodes exhibit excellent cycle life (up to 300 cycles) with high initial coulombic efficiency (80–90%) and large reversible capacity (>300 mAh g⁻¹). Molybdenum oxides also categorized as one of the conversion-type transition-metal oxides and applied as negative electrodes for LIBs and SIBs with a specific capacity approaching 1000 mAh g⁻¹. In addition to the discussion of the key aspects of crystal growth, characterization, an