Люминофоры холодного голубого излучения на основе оксида алюминия, допированного диспрозием

Al2О3:Dy3+ oxides with different colors luminescence were synthesized using precursor technology. The phase composition and crystal structure of the obtained materials were established by X-ray powder diffraction analysis. The excitation and emission spectra, decay curves, thermal quenching of luminescence were studied. Under UV excitation, the phosphors exhibit blue, purplish blue, white emission depending on the concentration of dysprosium and the temperature of annealing of the Al1-xDyx(OH)(HCOO)2 precursor in air.

Large interaction energy for the homodimer and the heterodimer extracted from the supramolecular chain of a bent trinuclear zinc(II) complex with a reduced Schiff base ligand

A bent trinuclear zinc complex, [Zn{ZnIL}2]•DMF {H2L = 2,2'-[(2,2-Dimethyl-1,3-propanediyl)bis(iminomethylene)]bis[6-methoxyphenol]} was synthesized and characterized by standard spectroscopic methods and X-ray diffraction analysis. The existence of coordinated amino groups and iodide counter...

A6Mo2P4O19 (A = Rb, Cs) and Rb2MoP2O9: New molybdophosphates with distinct polyanionic configurations

The exploration in the A-Mo-P-O (A = Rb, Cs) systems has allowed several new Mo(V) phosphates, Rb2MoP2O9, Rb6Mo2P4O19 and Cs6Mo2P4O19 synthesized through the spontaneous nucleation method. Single-crystal X-ray diffraction analysis...

History and Prospects for the Application of X-Ray Diffraction Analysis in Seed Breeding and Seed Study

Introduction. X-ray analysis has been applied for visualizing the internal structure of various objects for over 100 years. However, this method began to be used for assessing the quality of plant seeds only in the early 1980s. The main impediment was a lack of specialized instruments, particularly X-ray sources, that could provide informative images. Advancements in the field of microfocus radiography allowed significant results to be achieved, including the preparation of the National Standard GOST R 596032021 "Agricultural Seeds. Methods of digital radiography".Aim. An analytical review of Russian research studies in the field of X-ray diffraction analysis of plant seeds.Materials and methods. Key stages in the development of microfocus X-ray diffraction analysis of seeds and individual parts of plants for agricultural and other purposes are considered. The design of instruments, including digital ones, created for the implementation of the method are described.Results. In order to obtain informative X-ray diffraction images of plant seeds, which objects are generally characterized by small sizes and small density, the focal spot of the X-ray tube should not exceed several tens of microns under the voltage of not higher than several tens of kilovolts. As a system for visualizing a latent X-ray image, it is preferable to use image receivers based on a screen with a photostimulated phosphor or flat-panel solid-state X-ray detectors. These instruments have been successfully used to identify and describe the radiographic signs of a normal seed and nine main types of defects for 600 plant species.Conclusion. In comparison with the conventional contact radiography, microfocus radiography produces X-ray images of seeds with a projection magnification of the image up to several tens of times. Such images permit highly detailed visualization of the structure of seeds that differ slightly in density.

Scattering of X-ray Ultrashort Pulses by Complex Polyatomic Structures

The scattering of X-ray ultrashort pulses (USPs) is an important aspect of the diffraction analysis of matter using modern USP sources. The theoretical basis, which considers the specifics of the interaction of ultrashort pulses with complex polyatomic structures, is currently not well developed. In general, research is focused on the specifics of the interaction of ultrashort pulses with simple systems—these are atoms and simple molecules. In this work, a theory of scattering of X-ray ultrashort pulses by complex polyatomic structures is developed, considering the specifics of the interaction of ultrashort pulses with such a substance. The obtained expressions have a rather simple analytical form, which allows them to be used in diffraction analysis. As an example, it is shown that the obtained expressions can be used to study the structures of deoxyribonucleic (DNA) and ribonucleic (RNA) acids.

Aplicación del refinamiento Rietveld para la identificación de fases del ZnO obtenido por precipitación química

El óxido de zinc (ZnO), es un material semiconductor del tipo II-VI, el cual posee una energía de banda prohibida (Ebp) de 3.37 eV a 298.15 K y la estructura cristalina termodinámicamente más estable es la del tipo de la wurtzita (hexagonal). Con estas características, el ZnO es un candidato excelente para múltiples aplicaciones industriales tales como; la electrónica, magnética, fotocatalítica, optoelectrónica, metalúrgica, alimentaria, cosmética, farmacológica, cerámica, polimérica y muchas otras más. En el presente trabajo, se identificaron y cuantificaron las fases cristalinas presentes en muestras sólidas obtenidas por precipitación química, considerando la relación estequiométrica en medio alcalino. Para el análisis de las fases cristalinas presentes en los sólidos obtenidos se empleó la técnica de Difracción de rayos-X (DRX), los difractogramas se obtuvieron en un intervalo de 4 a 90 de 2θ, a una velocidad de paso de 0.02y de la aplicación del método de Refinamiento Rietveld se llevó a cabo con el empleo del software Materials Using Diffraction Analysis (MAUD). Los resultados cualitativos permitieron considerar la presencia predominante de fase wurtzita (ZnO), la smithsonita (ZnCO3), hidróxido de zinc (Zn(OH)2) y acetato de zinc (ZnC4H6O4). Los resultados del refinamiento permitieron identificar la presencia de fases secundarias de ZnO en estos sólidos, tales como la estructura de roca de sal (halita) y la blenda de zinc.