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The purpose of this work is to understand, for Ce doped materials, how the effect of the local crystal environment of Ce compared to the character of the host cation, influences the scintillation and fluorescence of different materials. In the case of YAP (YAlO3) and LAP (LaAlO3) while very similar materials, YAP is a moderately bright Ce activated scintillator while LAP shows no Ce activation. It...
Structural parameters and physical properties are tabulated for >100 presently known simple and binary acentric chloride crystals. Distribution of the crystals over point symmetry groups has been defined in comparison with that of fluorides. A rosette of ellipses of acentricity has been outlined on the plane of the shortest chemical bond lengths metal-chlorine in the crystal lattice. A combination...
Crystals of K3WO3F3 in low temperature ferroelectric modification, space group Cm, have been created by chemical synthesis. Crystal structure of this modification has been found by Reitveld method. Electronic parameters of the constituent element core levels have been measured with X-ray photoelectron spectroscopy. Chemical bonding in WO3F3 groups have been discussed.
Neural net analysis is tested as a tool for prediction of acentricity of crystal structure. A set of input parameters is defined that gives the prediction with as high probability as ~80%. The neural net is used for prediction of new binary acentric molybdates.
Quantitative relation has been defined that relate long-wavelength and short-wavelength limits of a crystal with its mean refractive index. The long-wavelength and short-wavelength limits have been predicted for a set of binary oxide crystals which crystal structure is known. The compounds promising for pronounced spectral parameters have been selected.
Poly(trimethylene terephthalate) (PTT), a flexible polymer containing C=O dipoles in its main chain is synthesized by the polycondensation of 1,3-propanediol and terephthalic acid. Numerous studies on the crystal structure of PTT have been reported. Analysis of crystalline structure of PTT shows that the trimethylene glycol unit in PTT takes a highly coiled structure of trans-gauche-gauche-trans conformation...
Interrelation of crystal chemistry parameters, structure and nonlinear optical properties of the niobate and iodate crystals has been established. The combination of chemical bond lengths in these compounds, which is contributed to high optical nonlinearities, is found. This allows to design new promising crystals for optoelectronics.
The results on nanocomposition modifying in solutions and melts of salts and acids, as well as structural changes associated with the formation of nanocomposition (NC) structure of materials are presented. The associated protonation is a necessary condition for proton separation of primary structure of nanopolymers (PSN) in NC structure model. The shape and size of PSN in simple substances and compounds...
An empirical way to classify the known tungstates and molybdates MmEnWpOt is presented. As a basic criterion the shortest chemical bond length L(E, M-O) between cation and oxygen in crystal lattice is taken. Here the cations E and M are defined by the relation L(E-O) les 200 pm <L(M-O). On the plane L(M-O) - L(E-O) the acentric tungstate and molybdate crystals are positioned inside three partly...
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