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EN
Derivatographic, dielectric and complex impedance studies of Rb_{4}LiH_{3}(SeO_{4})_{4} crystals revealed a superionic phase transition at T_{s} ≈ 448 K. The bulk conductivity rises from 10^{-6} to 10^{-4} (Ωm)^{-1} at T_{s}, and the activation energy of conductivity in the direction of crystal axes a and b (where a = b for tetragonal symmetry) W_{a} = W_{b} decreases from 0.94 eV in the low temperature phase to the value of 0.27 eV at T > T_{s}. The analysis of the results of X-ray studies at room temperature and at 450 K indicates that the fast ion transport, characterized by low activation energy, is related to the delocalization of the H2 protons in the O(12)-H2-O(24) bonds linking the Se(1)O_{4} and Se(2)O_{4} tetrahedra. The "cogwheel" mechanism is suggested to be involved in the fast proton transport.
EN
Magnetic and dielectric properties of hexagonal ferrites important for applications in microwave absorbers are strongly determined by the processing conditions. We studied dielectric and magnetic response of Sr_{1-x}Nd_{x}Fe₁₂O₁₉ (x=0, 0.03, 0.05, 0.07, 0.09) solid solutions obtained by coprecipitation method. The structure of the samples was controlled by X-ray diffraction and scanning electron microscope images revealed that the powder is a mixture of small nanograins and crystallites of 500 nm-1 μm in size. Nd³⁺ doping was found to result in an increase in the coercive field which we would like to relate to the domain wall pinning. The doping-induced changes are monotonous with x up to 0.07. The observed dispersion of permittivity was found to be correlated with the frequency behaviour of electric conductivity of the samples.
EN
GaAs:Zn whiskers grown by the gas-transport method are characterized by diffraction methods using white and monochromatic radiation. The methods applied include the white-beam topography at ESRF synchrotron source and Laue patterns, 4-circle Bond diffractometry and high-resolution diffractometry at conventional X-ray sources. The results obtained concern the growth morphology and defect structure. It is found that GaAs:Zn whiskers grown by the described method have the form of long needles and blades of the morphologies represented by growth direction and largest lateral face ⟨112⟩{111} and ⟨111⟩{112}, respectively, with a single exception of a blade of uncommon morphology ⟨111⟩{110}.
EN
Transmission electron microscopy and X-ray diffraction proved chain ladder incommensurate single crystal structure of investigated samples. The incommensurate ratio was determined from the X-ray and electron diffraction being equal to 0.704. Diffuse scattering intensities localised on the planes perpendicular to the c*-axis and passing through the spots originating from the periodicity of chain sublattice were detected. High-angle grain boundary or twinning formed by rotation of 33.3° around [100] direction was observed. High-resolution electron microscopy images revealed the stacking faults in ac planes.
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