Ion
transport properties of block copolymers with lamellar morphologies,
which contain ionic liquids (ILs), were investigated. By varying the
type of anion in the ILs, dissimilar substructures of lamellar microdomains
were identified using different elastic scattering techniques. By
decoupling the segmental motion of polymer chains from conductivity,
a wide range of normalized conductivities from 0.03 to 0.6 (theoretical
value of 1) were determined, depending on the type of IL. The highest
conductivity was achieved when ILs were confined within ionic domains
with a sharp interface, owing to the creation of less tortuous ion
conduction pathways. In contrast, a high degree of intermixing of
ionic and nonionic domains at the interface, because of IL incorporation,
revealed a reduction by 1 order of magnitude in the conductivity.
This work presents fascinating experimental insights into confinement-
and interface-driven modulation of ion transport properties for polymer
electrolytes and presents the future prospects for designing desired
nanostructures as efficient ion conductors.
Single phase nanoparticles (NPs) of CeO2, Ce0.5Zr0.5O2, Ce0.5Hf0.5O2 and Ce0.5Hf0.25Zr0.25O2 were successfully synthesized by co-precipitation method at constant pH and temperature. The X-ray diffraction results revealed that the additive atoms did not segregate to form secondary phases but led to grain size variation in the NPs. The 10 Dq values in the near edge X-ray absorption fine structure (NEXAFS) spectra at the O K-edge did not vary in the same way as the average grain size was changed for the doped CeO2 NPs. The deconvolution of Ce M5-edge and detailed analysis of O K pre-edge peak have shown the higher Ce(+3)/(Ce(+3) + Ce(+4)) ratio in the Zr- and Hf-doped samples. The local atomic structure around the Ce, Zr and Hf atoms was investigated using extended X-ray absorption fine structure (EXAFS) spectroscopy at Ce K-edge, Zr K-edge and Hf L3-edge, respectively, and the EXAFS data were fitted with the theoretical calculations. The 4f occupancy, Ce(+3)/(Ce(+3) + Ce(+4)) ratio of Ce ions, coordination number of Ce and Ce-Ce/Ce-O bond distances were sensitive to the additive atoms but not explicitly changed according to the grain size variation in the NPs.
The structural properties of normal-type spinel ZnCr 2 Se 4 have been studied as a function of temperature by means of X-ray diffraction using synchrotron radiation. It is found that a structural phase transition from cubic to orthorhombic symmetry occurs at 22.5 K (T c ). It is also found that, below T c , Se ions are cooperatively displaced in a pseudo-tetragonal (001) plane. Since the Cr 3+ ion has no orbital angular momentum, a CrSe 6 octahedron is not distorted by a crystal field produced by surrounding Se 2− anions. It is interpreted that the pseudo-tetragonal displacements of Se ions are induced by magnetostriction among Cr 3+ ions in CrSe 2 chains, in which Cr ions share two Se 2− with each other along 〈110〉.
We demonstrate a wideband circular polarization reflector fabricated as cascades of helical films with different pitch thickness by using glancing angle deposition (GLAD) technique. The full-width-at-half-maximum bandwidth of this reflector is measured from the reflectance spectra and is found about 200 nm indicating the feasibility of wideband reflector. A helical TiO(2) film with three sections, each of different pitch thickness, is also studied. It shows three Bragg peaks at different wavelengths. To select appropriate material for this circular reflector, the optical properties of 5-turns TiO(2), ZrO(2), and Ta2O(5) helical films and the porosity effect on the TiO(2) helical film are investigated.
Wafer-scale arrays of well-ordered Pb(Zr(0.2)Ti(0.8))O3 nanodiscs and nanorings were fabricated on the entire area (10 mm x 10 mm) of the SrRuO3 bottom electrode on an SrTiO3 single-crystal substrate using the laser interference lithography (LIL) process combined with pulsed laser deposition. The shape and size of the nanostructures were controlled by the amount of PZT deposited through the patterned holes and the temperature of the post-crystallization steps. X-ray diffraction and transmission electron microscopy confirmed that (001)-oriented PZT nanostructures were grown epitaxially on the SrRuO3(001) bottom electrode layer covering the (001)-oriented single-crystal substrate. The domain structures of PZT nano-islands were characterized by reciprocal space mapping using synchrotron x-ray radiation. Ferroelectric properties of each PZT nanostructure were characterized by scanning force microscopy in the piezoresponse mode.
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