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Full-Text Articles in Physical Sciences and Mathematics
Cacu3ti4o12: Low-Temperature Synthesis By Pyrolysis Of An Organic Solution, Jianjun Liu, Yucheng Sui, Chun-Gang Duan, Wai-Ning Mei, Robert W. Smith, John R. Hardy
Cacu3ti4o12: Low-Temperature Synthesis By Pyrolysis Of An Organic Solution, Jianjun Liu, Yucheng Sui, Chun-Gang Duan, Wai-Ning Mei, Robert W. Smith, John R. Hardy
Chemistry Faculty Publications
The giant-dielectric-constant material CaCu3Ti4O12 (CCTO) has been synthesized by pyrolyzing an organic solution containing stoichiometric amounts of the metal cations, which is done at lower temperature and shorter reaction time than the conventional solid-state reaction. A stable solution was prepared by dissolving calcium nitrate, copper(II) nitrate, and titanium(IV) isopropoxide in 2-methoxyethanol. This solution was pyrolyzed and heat-treated to achieve single-phase CCTO. The phases, microstructures, and dielectric properties of intermediate and final samples were characterized by X-ray diffraction, scanning electron microscopy, and dielectric spectroscopy.
Electrical Properties And Raman Scattering Study Of Single Crystal Cs2nb4o11, Jianjun Liu, E. P. Kharitonova, Chun-Gang Duan, Wai-Ning Mei, Robert W. Smith, John R. Hardy
Electrical Properties And Raman Scattering Study Of Single Crystal Cs2nb4o11, Jianjun Liu, E. P. Kharitonova, Chun-Gang Duan, Wai-Ning Mei, Robert W. Smith, John R. Hardy
Chemistry Faculty Publications
We studied temperature dependence of complex capacitance, impedance, and polarized Raman spectra of single crystal Cs2Nb4O11. First, we observed a sharp-shaped peak at 165 oC in the complex capacitance, then found drastic changes in the Raman spectra in the same temperature range. Utilizing the pseudosymmetry search of structure space group, we attributed the observed anomalies to a structural change from the room temperature orthorhombic Pnn2 to another or- thorhombic Imm2. We also measured room temperature polarized Raman spectra in different symmetries of normal vibrations and assigned high wavenumber Raman bands to the internal vibrations of NbO6 octahedra and NbO4 …