Papers by Keyword: Crystals

Abstract: A method was developed for synthesis of a single phase lithium tantalate charge doped by rare earth elements (TR) from highly pure solutions containing tantalum. The method is based on obtaining and thermal treatment of citrate precursor containing Li, Ta and TR. Charge samples were obtained due to suggested technological scheme; the dopant had given concentration and was chemically uniformly distributed. The charge can be applied both in single crystal growing technology and at obtaining of functional ceramics based on LiTaO₃:TR.

Abstract: Oral rehydration fluids (ORS) are used to reverse dehydration that, in case of children, mostly is due to acute gastroenteritis. The key of successful dehydration treatment is to replenish the lost water and electrolytes. This is best done by consuming oral rehydration solution, containing both salt and sugar. ORS enhances fluid absorption because sodium and glucose transport in the small intestine are coupled, and glucose promotes absorption of both sodium ions and water. Studies show that children refuse ORS due to its salty-sweet taste and unpalatability. To improve oral rehydration therapy, we hypothesized that freezing ORS containing a fruit/berry juice to a likeable texture in “gelato” form could promote oral rehydration. The results provide a basis for further development of the ORS gelato with attention to flavor, sweetness and texture.

Abstract: In this article the self-hardening structure of stone based on calcium sulfate formation is described. Increase of strength of gypsum is possible by additional reinforcing of a stone ettringite crystals. The form and character of the formed crystals is defined by size рН. Dependence рН from the maintenance of additives was investigated in work. The limiting factor of formation of crystals of an ettringite of a necessary look is the maintenance of an additive. In work gypsum composites with the improved physical-mechanical properties on the basis of the modifying complex are received and investigated.

Abstract: X-ray imaging represents a very relevant tool in basic and applied research fields due to the possibility of performing non-destructive investigations with high spatial resolution. We present innovative X-ray imaging detectors based on visible photoluminescence from aggregate electronic defects locally created in lithium fluoride (LiF) during irradiation. Among the peculiarities of these detectors, noteworthy ones are their very high spatial resolution (intrinsic ∼2 nm, standard ∼300 nm) across a large field of view (>10 cm²), wide dynamic range (>10³) and their insensitivity to ambient light. The material photoluminescence response can be enhanced through the proper choice of reflecting substrates and multi-layer designs in the case of LiF films. The present investigation deals with the most appealing X-ray imaging applications, from simple lensless imaging configurations with commonly-available laboratory polychromatic X-ray sources to X-ray imaging-dedicated synchrotron beamlines in absorption and phase contrast experiments.

Abstract: The article examines the impact of nanodefects on the reduction of the crystals strength. A summary of the authors research results is illustrated by the analysis example of the NaCl crystal destruction process from the standpoint of strength quantum theory. As the base experiment is seen testing the dry and wet a salt crystal made by academician A. Ioffe. The authors research aim was a little-studied patterns of the crystal lattice destruction quantum mechanism. The article gives a brief historical background of the research in this area. The first section discusses the rystal cell dynamic characteristics change as a result of destruction. Assesses self-resonant frequency of an atom at a lattice point of the crystal before and after the destruction. In the second section of the article examines the relationship between the natural frequencies of the atoms in the lattice and elastic energy wich accumulated in the crystal body in the force loading process. The main attention is paid to theoretical modeling of the links strength between atoms in the crystal surface layer. We study the strength dependence of these relationships to the availability of nanodefects on the crystal surface. There are modeled bond strength to clean the crystal surface, as a result of the surface lattice electrification when atoms capture free electrons and for the case when jobs of atoms in the crack are filled with the external environment atoms. The calculations confirm the validity of the proposed theoretical model of reduction or the hanging of the crystals strength by the atoms interaction with the external environment.

Abstract: Ammonium dihydrogen phosphate (ADP) crystals is very interesting due to its nonlinear optical property. This study investigated on improving of material for academic use by adding boric acid to modify ADP crystals. Slow evaporation method in aqueous solutions of pure ADP and ADP doped with three concentrations of H₃BO₃ as 0.1, 1.0, 5.0 %wt were studied. The grown crystals were confirmed tetragonal structure by powder X-ray diffraction studies. The FTIR spectrum analysis presented various functional groups of boron in three conditions of doped ADP. TGA study was comfirned the temperature stability at 220 °C for both pure and doped ADP crytals. The machanical stress was analyzed by Vicker’s hardness measurement. The results of this analysis showed boric acid doped 1.0 %wt had superior machanical stress from 10 to 75 grams. ADP doped with boric acid at 1.0 %wt was accepted in all test properties.

Abstract: Storage properties of water-soluble salts in bastion historical brick are presented in this paper. Probably the most important factor affecting the material degradation represents water from rain, snowfalls or ice, which penetrates into the unprotected parts of building. Therefore, the deterioration of building materials is in many cases caused by water-soluble salts. The most common salts are on chloride, sulfate and nitrate origin. The aim of this article is influence of salts ions on masonry from bastions fortifications. The main practical impact will be in providing more precise information about material so it should lead to improvement the quality of reconstruction process of historical buildings.

Abstract: In the work, magnetization-induced second-harmonic generation (MSHG) effect has been appliedto investigate the magnetization distribution changes, induced by ion implantation into thethin surface layer of garnet film.The studies were performed on the (111)-orientedepitaxial garnet film (YSmLuCa)$_3$(FeGa)$_5$O$_{12}$ implanted with $1.5\times10^{16}$~cm$^{-2}$dose of H$_2^+$ ions at $60$~keV energy. The measurements of the MSHG effectwere performed as a function of amplitude of perpendicular external magnetic field. The observed complex field dependencesof the remagnetization processes for the implanted garnet film studied were described in theframe of a phenomenological model developed. The model of the MSHG effect allows to performdecomposition of measured dependences on separate contributions originating from magnetizationcomponents related to implanted and unimplanted film volumes.

Abstract: In this paper the author’s main goal was to determine if the roughness of the substrate (a Ti6Al4V alloy) shows any influence on the hydroxyapatite (HA) crystal morphology and distribution. Disks of Ti6Al4V, 24mm in diameter and 1mm thickness are sandblasted with Al₂O₃ particles with different mean size: 29, 45 and 110μm. The disks are analyzed prior coating by atomic force microscopy (AFM) to determine the surface roughness. The samples are then cleaned and coated with HA by immersion in a solution derived from [Ca (NO₃)₂.4H₂O] and P₂O₅ dissolved in ethylene glycol – the process was repeated 3 times. The coated samples are analyzed by scanning electron microscopy (SEM) to observe HA crystal shape, size and distribution.

Abstract: To calrify the combined effect of soft template and biominormolecule on the formation of hydroxyapatite (HAp), the study on the growth of HAp regulated by citrate and(or) hexadecyltrimethylammonium bromide (CTAB) solution was developed in a thermal aqueous. The as-obtained products were characterized by XRD, FT-IR and TEM, altogether with HRTEM and ED. Plate-like HAp crystals in nanosize with relative weak crystallinity were obtained in the presence of citrate. Nano-needle shape HAp crystals were produced in the presence of CTAB. Rod-like HAp crystals in a uniform nanosize were formed under the regulation of CTAB and citrate, which showed the same orientation as that of CTAB only. However, the possible mechanism of the growth of HAp was discussed in detail. CTAB micelles worked as a soft template modified by citrate, which guided to form HAp crystals in different morphology. The study is benefit to control the formation of HAp for its bioapplication.