55 research outputs found
Physico-Chemical Changes Occurring in Gamma Irradiated Flours Studied by Small-Angle X-ray Scattering
Commercial samples of wheat, rye and potato flour and flaked oats, as well as ground flaked oats and fresh potatoes were gamma-irradiated (20 or 30 kGy dose). The products and appropriate control samples were inves tigated by small-angle X-ray scattering (SAXS) in the range of 28 from 0.357 to 6.46 degree (CuKa radiation). The results were compared with those obta ined for pure potato starch. Effects of grinding and heating at 100° Con SAXS results were also examined.
Different scattering curves were obtained for various unirradiated products. Refl ect ions derived from starch were de tected for some uni rradiated :ls well as irradiated products. A reflection connected with long-range ordering in sta rch (co rresponding to the distance d =: 10 nm)was observed for potato, wheat, rye flour and potato powde r. A reflection corresponding to the distanced = 1.6 nm (due to short-range ordering) was observed in the cases of potato flour and potato powder. Comparison of diffractograms of gamma- irradiated and unirradiated products, have revea led changes of the reflection corresponding to d = 10 nm intensity and elevation of scattering curves, connected with changes of long-range ordering in starch gra nules. The effect of gamma-irradiation on long-range ordering in starch was also observed aft er heating of starch at 100°C. Heating at 100°C as well as grinding, cause diminution of long-range ordering m starch granules
Growth conditions, structure, and superconductivity of pure and metal-doped FeTe1-xSex single crystals
Superconducting single crystals of pure FeTe1 xSex and FeTe0.65Se0.35 doped
with Co, Ni, Cu, Mn, Zn, Mo, Cd, In, Pb, Hg, V, Ga, Mg, Al, Ti, Cr, Sr or Nd
into Fe ions site have been grown applying Bridgman's method. It has been found
that the sharpness of transition to the superconducting state in FeTe1 xSex is
evidently inversely correlated with crystallographic quality of the crystals.
Among all of the studied dopants only Co, Ni and Cu substitute Fe ions in
FeTe0.65Se0.35 crystals. The remaining examined ions do not incorporate into
the crystal structure. Nevertheless, they form inclusions together with
selenium, tellurium and/or iron, what changes the chemical composition of host
matrix and therefore influences Tc value. Small disorder introduced into
magnetic sublattice, by partial replacement of Fe ions by slight amount of
nonmagnetic ions of Cu (~ 1.5 at%) or by magnetic ions of Ni (~ 2 at%) and Co
(~5 at%) with spin value different than that of Fe ion, completely suppresses
superconductivity in FeTe1 xSex system. This indicates that even if
superconductivity is observed in the system containing magnetic ions it can not
survive when the disorder in magnetic ions sublattice is introduced, most
likely because of magnetic scattering of Cooper pairs.Comment: 18 pages, 12 figures, 3 table
The investigation of YAlO3-NdAlO3 system, synthesis and characterization
The binary phase diagram of the YAlO3 (YAP) - NdAlO3 (NAP) system was
determined by differential thermal analysis (DTA) and X-ray powder diffraction
(XRD) measurements. High purity nanocrystalline powders and small single
crystals of Y_{1-x}Nd_{x}AlO_3 (0 \leq x \leq 1) have been produced
successfully by modified sol-gel (Pechini) and micro-pulling-down methods,
respectively. Both end members show high mutual solubility >25% in the solid
phase, with a miscibility gap for intermediate compositions. A solid solution
with x \approx 0.2 melts azeotropic ca. 20 degrees below pure YAP. Such
crystals can be grown from the melt without segregation. The narrow
solid/liquid region near the azeotrope point could be measured with a "cycling"
DTA measurement technique.Comment: 12 pages, 8 figures, submitted to J. Alloys. Comp
Surface Fractal Dimension of Single-walled Carbon Nanotubes
Isolated single-walled carbon nanotubes (SWNTs), SWNT bundles, and ropes (or strands) show a structural self-similar characteristic. By calculating the Hausdorff dimension, it was found that their self-similar organization leads to surface fractality and the value of the surface dimension (Ds) depends on self-similar patterns. Experimentally, Ds obtained by nitrogen adsorption measurements at 77.3 K and by the small-angle x-ray scattering technique in our study proved our calculation that the surface dimension of SWNTs is nonintegral,
Short range order In Pd and PdO nanoparticles embedded In carbonaceous matrix studiem with the XAFS spectroscopy
WEAK FERROMAGNETISM OF Fe INTERCALATED FULLERIDES
The magnetic properties of C 60 Fex resemble spin glass with the freezing onset above 200 K. The unusual magnetization behavior at intermediate temperatures is ascribed to bonds reorganization
Weak Ferromagnetism of Fe Intercalated Fullerides
The magnetic properties of CFe resemble spin glass with the freezing onset above 200 K. The unusual magnetization behavior at intermediate temperatures is ascribed to bonds reorganization
Synthesis and luminescent properties of Sr<sub>2</sub>CeO<sub>4</sub>
Sr2CeO4 stanowi atrakcyjny materiał ze względu na praktyczną możliwość wykorzystania go w przemyśle np. w konstrukcji wyświetlaczy z emisją polową. Zsyntetyzowano luminofor za pomocą dwóch niezależnych metod. W każdej z nich zostały wykorzystane inne rodzaje substratów. Zbadano skład fazowy produktów za pomocą analizy rentgenowskiej XRD, mikrostrukturę za pomocą skaningowej mikroskopii elektronowej SEM oraz wykonano pomiary luminescencji.From an industrial perspective, Sr2CeO4 is a particularly promising material because of the possibility of its practical application, for example to the construction of field emission displays. In this work, phosphor was synthesized by two independent techniques, namely a solid state method and a sol-gel method using different starting chemicals. The phase composition was examined by an X-ray diffraction method (XRD), whereas microstructure by scanning electron microscopy (SEM). In the end, the luminescence spectra were recorded
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