Comment on “Stable phase domains of the TiO2–Ti3O5–Ti2O3–TiO–Ti(CxOy)–TiC system examined experimentally and via first principles calculations” by J. Kim and S. Kang, J. Mater. Chem. A, 2014, 2, 2641

The free energy of mixing in the Ti(O,C) shows negative deviation from ideality. A recent paper, Journal of Materials Chemistry A, 2014, 2, 2641, erroneously shows a large positive deviation from ideality.

Identity-reaction proton transfers from oxygen acids yielding localized vs. delocalized conjugate bases. An ab initio study

Identity-reaction proton transfers from a series of oxygen acids to the corresponding conjugate bases have been studied by ab initio methods at the MP2/6-31+G*//MP2/6-31+G* level. The acids are H3O+, CH3OH2+, CH2 = OH+, HC(O)OH2+, CH2 = CHOH2+, H2O, CH3OH, HOOH, HOCH2OH, FOH, FCH2OH, HC(O)OH, and CH2 = CHOH. Gas-phase acidities were calculated at the G2(MP2) level in order to have benchmark values for all acidities regardless of whether experimental values were available. Barriers to proton transfer relative to the separated reactants, ΔHTS, show a straight-line relation to acidity for all but two of the neutral acids and for all but one of the cationic acids. Two neutral acids, HOOH and FOH, show negative deviations that can be attributed to polarizability of the atoms attached to the proton donor oxygens. The cationic acid HC(O)OH2+ shows a large positive deviation, which probably arises from substantial heavy-atom reorganization from reactant to TS. Charges provide evidence of a lag in delocalization in the reaction of CH2 = CHOH2+, though it does not show an elevated ΔHTS.Key words: ab initio, oxygen acids, proton transfer, acidity.

Magnetization and Interactions of Single Domain Sm2Co17 Particles Embedded in CaO Matrix

ABSTRACTInvestigation of the interactions in two magnetic composite systems composed of ∼8 vol% isolated Sm2Co17 nanoparticles of different size ranges in a CaO matrix has been made by comparing the isothermal remanent magnetization curves (IRM) with the dc demagnetization curves (DCD) using Wohlfarth remanence relation. The presence of a weak demagnetizing field was evidenced in the sample with smaller magnetic particles (7-90nm), indicating the magnetostatic interaction between the magnetic particles was dominant in this sample. The large positive deviation from Wolhfarth relation in the sample with larger particles (10-250nm) suggests the presence of multigrain particles in which neighboring grains interact strongly with each other. The hysteresis curves of the two composite systems were measured at temperatures between 5 and 350K. A nearly linear temperature dependence of the coercivity was observed in both samples up to 350 K. From these results it is shown that although the sizes of the Sm2Co17 particles are well below the critical size for single domain particle, there is no evidence that the magnetization reversals in these particles are coherent rotation.