Field-induced splitting of the OH-Stretch absorption line in KTaO3 and KTaO3 :Li

Abstract

We have studied the electric field-induced splitting of a single OH stretch mode in KTaO₃ and KTaO₃ :Li. For the three prominent directions [100], [110] and [111] we observed polarized splitting patterns with up to six components. The line positions exhibit no mirror symmetry with respect to the zero-field frequency. This behaviour can be interpreted by taking into account a field-dependent shift of the Ta⁵⁺ ion and a change of the covalent character of the bond. Li-doped KTaO₃ samples show for [Li] < 2mol% a line broadening, while for [Li] < 3.5 mol% a field dependent phase transition has been observed with evidence for a 90 degree domain structure.     

Physicochemical investigation of some archaeometallurgical findings from locality Kmpije (Bor,Serbia)

Preliminary results of physicochemical investigation of some archaeometallurgical findings from Kmpije locality in vicinity of Bor (Serbia) are presented in this paper. Ancient samples of prehistoric origin were investigated using different instrumental analytic methods—chemical, differential thermal, X-ray diffraction, and energy dispersive X-ray fluorescence analysis. Obtained results indicate to the presence of ancient metallurgical activities, so locality Kmpije may be considered as an archaeometallurgical site, which should be investigated more in future for more precise details.     

Crystal structure of K[PtCl3(caffeine)] and its interactions with important nitrogen-donor ligands

The crystal structure of K[PtCl₃(caffeine)] was determined. The coordination geometry around platinum is square-planar formed by N9 of the caffeine ligand and three Cl^? ions. The bond lengths and angles of K[PtCl₃(caffeine)] were compared with those reported for [PtCl₃(caffeine)]^? and K[PtCl₃(theobromine)]. At the level of the statistical significance of the data we have compared, no differences in the bond distances and angles for any of these compounds were noticed. Weak interactions between K⁺ and Cl^? are responsible for the formation of 1-D polymeric chains in the crystal structure of the complex. The interactions of K[PtCl₃(caffeine)] with inosine (Ino) and guanosine-5′-monophosphate (5′-GMP) were studied by ¹H NMR spectroscopy at 295 K in D₂O in a molar ratio of 1 : 1. The results indicate formation of the reaction product [PtCl₃(Nu)] (Nu=Ino or 5′-GMP) with the release of caffeine from the coordination sphere of the starting complex. The higher stability of the bond between the Pt(II) ion and Ino or 5′-GMP compared to the stability of the platinum–caffeine bond is confirmed by density functional theory calculations (B3LYP/LANL2DZp) using as models 9-methylhypoxanthine and 9-methylguanine.     

Difference schemes for a general parabolic problem with interface

Stability and convergence of finite difference schemes approximating a general parabolic partial differential equation with interface are examined. Convergence rate estimates compatible with the smoothness of the input data are obtained. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

On the strong stability of differential equations and difference schemes

Paper deals with the construction of a priori estimates for the solution of Cauchy problem for an abstract linear differential equation in Hilbert space under perturbations of the initial condition, right-hand side, and operators of the problem. It is shown that a priori estimates of strong stability can be obtained directly on the basis of various a priori estimates for the solution of the Cauchy problem. The perturbations of the operators of the problem are estimated in the corresponding operator norms. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Dependence of the probability of biological effects per hit,induced by radiation emitted by <Superscript>222</Superscript>Rn,from alpha particle energies and the geometry of tracheobronchial tree

Biological effects of radiation in terms of their effect on living cells are considered in this work. In dosimetry of the human lung exist the need to include the influence of the biological effects. The aim of this work is to calculate the probability of biological effects (transformation cell and production of lesion) per hit induced by alpha particle radiation on sensitive cells of human lung. Probability was calculated by applying the analytical model cylinder bifurcation (Nikezić et al., Int J Radiat Biol 79(3):175–180, 2003; Nikezić and Yu, Radiat Environ Biophys 42:49–53, 2003) which was created to simulate the geometry of human lung with the geometric distribution of cell nuclei in the airway wall of the tracheobronchial tree. This analytical model of the human traheobronchial tree represent the exstension of the ICRP66 model, and follows it as much as possible. Reported probabilities are calculated for various targets and alpha particle energies in order to show dependence of the probability of biological effects (transformation cell and production of lesion) per hit from alpha particle energies and the geometry of tracheobronchial tree for the human lung.     

Optical and dielectric properties of fluorinated ethylene propylene and tetrafluoroethylene–perfluoro(alkoxy vinyl ether) copolymer films modified by low energy N and C ion beams

Fluorinated ethylene propylene (FEP) and tetrafluoroethylene–perfluoro(alkoxy vinyl ether) (PFA) copolymer films were irradiated in vacuum with 60 keV C⁴⁺ and N⁴⁺ ions to fluences ranging from 1.0×10¹² to 5.0×10¹⁵ cm⁻². Changes in optical and dielectric properties were analyzed by spectroscopic ellipsometry and ultraviolet–visible (UV–vis), Raman and dielectric relaxation spectroscopies. Direct and indirect energy band gap values were determined from the absorption edge in the 200–800 nm region using Tauc's relation. The values of the direct energy gap have been found to be greater than the corresponding values of the indirect energy gap. Significant changes in the index of refraction, and β and γ dielectric relaxations were observed in the case of N⁴⁺ irradiated FEP and PFA samples.     

Electrometric titrations with a single polarised electrode Determination of hydrogen peroxide and manganese

A simple electrometric method for end-point detection, based on the lack of response of the indicator electrode in the titrated irreversible system has been described. The end-point is reached at the beginning of depolarisation of the electrode, when the equilibrium in the pre-balanced circuit is destroyed, producing an offbalance current.