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Structural diversity in layered hybrid perovskites, A2PbBr4or AA′PbBr4, templated by small disc-shaped amines
Three new layered hybrid perovskites are reported. (TzH)2PbCl4 undergoes a unique structural phase transition, due to ‘rippling’ of perovskite-like layers.
The crystal structures of three new hybrid organic-inorganic lead halide compounds [IqH]PbI3, [4MiH]PbI3, and [BzH]PbI3 ([IqH+] = isoquinolinium, [4MiH+] = 4-methylimidazolium, [BzH+] = benzotriazolium) have been determined by single crystal x-ray diffraction. All three compounds have the same generic formula as perovskite, ABX3, but adopt a rare non-perovskite structure built from one dimensional (1D) edge-sharing octahedral chains. The bandgap of each compound was investigated by solid UV-Vis spectra. In comparison with previously reported hybrid compounds containing the same type of octahedral chains, [C10H7CH2NH3]Pbl3 and (C7H7N2)PbI3, all three new compounds have lower bandgaps (<2.4 ev), indicating that they may be promising for photovoltaic application.
Sintered molybdenum is widely used in the industry as an electrode for smelting furnace of glass and refractory, the crucible of rare earth metallurgy, and the thimbles for producing seamless steel tube and so on because of its strength at elevated temperature, good thermal properties, low sputtering yields and resistance to swelling. These unique properties of molybdenum make it a good candidate as a refractory metal. However, its further applications were limited by the brittleness characteristic and therefore many new molybdenum alloys were developed for improving ductility, among which the oxide dispersion strengthened molybdenum alloy (ODS Mo) is especially of interest. The ODS Mo, prepared by adding a proper amount of rare earth oxides (La 2 O 3 , Y 2 O 3 etc.) and by deforming to a large amount, exhibits a much higher recrystallization temperature than commercial pure molybdenum, [1±6] which makes ODS Mo show not only superior non-sag property and creep resistance at high temperatures but also superior strength and ductility at low temperatures as compared with the pure molybdenum. [7±9] Many explanations have been suggested on the strengthen mechanism of oxide dispersion strengthened molybdenum alloy. Hiraoka et al. attributed the improvement of low-temperature brittleness to the elongated coarse grain structure, [7] Deng shiqiang et al. thought that rare earth could decrease the density of C, N, O on the grain boundaries, [8] whereas
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