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Seo, Dong Wan,Lim, Young Don,Islam Mollah, M. S.,Lee, Soon Ho,Moon, Sang Ho,Pyun, Sang Young,Kim, Whan Gi Trans Tech Publications, Ltd. 2009 Materials science forum Vol.620 No.-
<P>Poly(ether sulfone)s (PES) containing 25-75 mol % valeric acid were prepared with bisphenol A, bis(4-chlorophenyl)sulfone and 4,4-Bis(4-hydroxylphenyl)valeric acid using potassium carbonate in DMAc (dimethylacetamide) at 160 °C. Copolymers containing carboxylacid group were reduced to hydroxy group by BH3 solution 1M in THF and NaBH4 co-catalyst. Sulfonated poly(ether sulfone)s (S-PES) were obtained by reaction of 1,3-propanesultone and the reduced copolymer (PES-OH) with potassium t-butoxide. A series of copolymers were studied by 1H-NMR spectroscopy, differential scanning calorimetry (DSC), and thermo gravimetric analysis (TGA). Sorption experiments were conducted to observe the interaction of sulfonated polymers with water and methanol. The S-PES membranes exhibited proton conductivities from 1.20 10-3 to 3.40 10-3 S/cm, water swell from 12.25 to 31.50 %, IEC from 0.43 to 0.72 meq/g and methanol diffusion coefficients from 3.60 10-7 to 4.90 10-7 cm2/S at 25 °C.</P>
X-ray Absorption and Emission Spectroscopic Studies of BiMn2-xTixO5 (0 ≤ x ≤ 0:5)
K. H. Chae,P. Thakur,황정남,G. S. Chang,D. K. Shukla,S. Mollah,Ravi Kumar 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.3
The electronic structure of the multiferroic BiMn2-xTixO5(0 ≤ x ≤ 0:5) system was studied by using X-ray absorption spectroscopy (XAS) and X-ray emission spectroscopy (XES). The polycrystalline bulk BiMn2-xTixO5 samples were synthesized using a conventional solid-state reaction technique. XAS and XES spectroscopic studies on the O K-, Mn K-, L3;2- and Ti L3;2-edges of the BiMn2-xTixO5 samples and of the reference compounds were performed and the results were compared in order to determine the exact chemical states of functioning ions. The O K-edge XAS and XES results demonstrate a competition between the Mn 3d and the Ti 3d orbitals on hybridizations with the O 2p orbital. The Mn K- and Mn L3;2-edge XAS spectra suggest that the Mn3+ /Mn4+ ratio increases with increasing Ti doping and drives the system towards octahedral symmetry. On the other hand, Ti ions remain at 4+ states for all compositions, as shown by the Ti L-edge XAS. Here, we present and discuss the detailed electronic structures of the BiMn2-xTixO5 samples.