By combining temperature-dependent x-ray diffraction (XRD) with temperature-dependent Raman scattering, we have characterized the structural transitions and lattice dynamics of the hybrid organic–inorganic perovskite CH3NH3PbI3. The XRD measurements cover distinct phases between 15 K and 370 K and demonstrate a general positive thermal expansion. Clear anomalies are found around the transition temperatures. The temperature evolution of the lattice constants reveals that the transition at 160 K/330 K is of the first-/second-order type. Raman measurements uncover three strong low-frequency modes, which can be ascribed to the vibration of the Pb/I atoms. The temperature evolution of the modes clearly catches these transitions at 160 K and 330 K, and confirms the transition types, which are exactly consistent with the XRD results. The present study may set an experimental basis to understand the high conversion efficiency in methylammonium lead iodide.

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In the present work, the high-rate epitaxial growth for superconducting YBa2Cu3O7-δ (YBCO) films on the substrates of LaMnO3(LMO)/IBAD-MgO/Y2O3/Al2O3/Hastelloy is achieved by fluorine-free metal organic deposition (FF-MOD) by rapidly switching the partial oxygen pressure (pO2) at a fixed temperature. Further investigation into the effects of temperature and switching pO2 on the phase transition of YBCO elucidates that the growth mode and microstructural characteristics of the studies films. BaMnO3 heterogeneous particles is observed in localized regions in the films by cross-sectional transmission electron microscopy (TEM), which may be generated by the interfacial reactions between the substrate and transient liquid phases. The present work implies the feasibility of FF-MOD for rapid growth of YBCO films on LMO buffered metallic substrates, regardless of interfacial reactions during the preparation.

For the difference between the traditional ontology and event ontology, this paper proposes a new event ontology storage mode and implements an event ontology system to manage the event ontology. The experiments show that the proposed mode has a higher query efficiency and lower data redundancy comparing to the XML storage mode. In addition, the new storage mode can preserve integrate semantic information of the event.

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Organo-phosphorus compounds S 0080 Synthesis and Structure Elucidation of New Spiro Compounds with Polyfluoroalkyl and Phosphonate Ester Groups. -The mechanism leading to novel spiro intermediates (V) is briefly discussed. -(SHI*, Z.; ZHAO, Y.; CAO, W.; ZHANG, S.; LIU, M.; Synth.