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The surface chemical states of the perovskite-type compounds, strontium doped lanthanum cobalt oxides (La1?x Sr x CoO3), have been investigated using X-ray photoelectron spectroscopy (XPS). Catalytic oxidations of both methane and CO have also been investigated using flow methods. The chemical composition of the surface of La1?x Sr x CoO3 was very different from that in the bulk, which was measured by X-ray fluorescence spectroscopy (XRFS). The catalytic activity of La1?x Sr x CoO3 increased with an increase in the quantity of cobalt atoms on the surface. 相似文献
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Valence-band spectra of La2CuO4 and YBa2Cu3O7 were obtained by using X-ray photoemission varying the temperature of the measurement (35, 260, 300, and 500 C). In La2CuO4 the broad band centred around 4eV splits into two peaks at 260 C. At both 35 and 500 C the spectra show almost similar shape. In YBa2Cu3O7 the broad peak centred around 4eV splits into two peaks at 500 C. Below 300 C the spectra show almost similar shape. These splittings of the valence-band spectra may be due to the rearrangement of the crystal structure accompanying the phase transition from the orthorhombic to tetragonal symmetry. 相似文献
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Koichi OkadaShigemi Kohiki Suning Luo Daiichiro SekibaSatoshi Ishii Masanori MitomeAtsushi Kohno Takayuki TajiriFumiya Shoji 《Thin solid films》2011,519(11):3557-3561
Thin films of indium tin oxide (ITO) sputter-deposited by dc-plasma containing deuterium on glass substrate without any heat treatments exhibited gradual lowering in electrical resistivity with increasing the deuterium content [D2] in plasma gas by 1% and then demonstrated a jump in resistivity by further increase of [D2] than 1%. X-ray photoelectron spectroscopy revealed that hydroxyl-bonded oxygen in ITO grew continuingly with [D2]. Deuterium positioned at the interstitial site increased almost quantitatively with increasing [D2]. Rutherford backscattering spectroscopy showed gradual reduction in the oxygen content of ITO with increasing [D2] by 1% and then demonstrated an abrupt increase of the oxygen content with the increase of [D2] than 1%. The films with [D2] < 1% were oxygen deficient, but those with [D2] > 1% were excess of oxygen. The most oxygen deficient film of [D2] = 1% was the most conductive. Behavior in the resistivity with [D2] looks parallel to that in the oxygen content. A lower resistivity of the films corresponded well to oxygen vacancy rather than hydrogen interstitial. 相似文献
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Kyoko Hori Masahiro Fukuta Hirokazu Shimooka Shigemi Kohiki Toetsu Shishido Masaoki Oku Masanori Mitome Yoshio Bando 《Journal of Alloys and Compounds》2005,390(1-2):261-264
β-Ga2O3 nanocolumns straightened and crossed perpendicularly each other were deposited on MgO (1 0 0) substrate by vapor phase transport method. Growth of the nanocolumns was examined at steps of 1000, 1050, and 1200 °C in elevation of source-boat temperature. We have drawn out the substrate from deposition-tube at each source-boat temperatures of 1000, 1050, and 1200 °C. Scanning electron microscopy of the sample with source-boat temperature of 1200 °C demonstrated that the straightened and elongated nanocolumns are crossing perpendicularly each other. Typical lengths of the nanocolumns were in the range of several hundreds nanometers below 1050 °C, and those of 1200 °C were in the range of ten to fifteen hundreds nanometers. Diameters of the nanocolumns stayed in the range of few hundreds nanometers, notwithstanding variation of the source temperature. X-ray diffraction and transmission electron microscopy with energy dispersive X-ray spectroscopy revealed that the nanocolumns are monoclinic β-Ga2O3 crystal, and the (4 0 0) plane of β-Ga2O3 nanocolumns is parallel to the (1 0 0) plane of MgO substrate. 相似文献
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Suning Luo Koichi Okada Shigemi Kohiki Fuki Tsutsui Hirokazu Shimooka Fumiya Shoji 《Materials Letters》2009,63(6-7):641-643
Polycrystalline thin films of indium tin oxide sputter-deposited in the working gas containing hydrogen of 0.3–1.5% exhibited transmittance of ≥ 80% for visible lights and blue-shift of ≥ 0.1 eV in the optical absorption energy. The film deposited in the gas containing hydrogen of 1% demonstrated almost flat temperature-dependent resistivity and the lowest resistivity of ≈ 1.5 × 10? 4 Ω cm at room temperature. The carrier density showed an inverse V-shaped behavior with the maximum at the hydrogen concentration of 1%. The mobility stayed at almost constant below the hydrogen concentration of 1% and dropped rather rapidly above 1%. 相似文献
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The surface chemical states of the perovskite-type thorium- or strontium-doped lanthanum cobalt oxides (La1–x
Th
x
CoO3, La1–x
Sr
x
CoO3) have been investigated using X-ray photoelectron spectroscopy. Catalytic oxidations of CO have been also investigated by flow methods. The ionicity between cobalt and lattice oxygen was increased by substituting thorium for lanthanum, and had a peak atx = 0.02. The catalytic activity also had a peak atx = 0.02. However, the ionicity decreased for the case of strontium substitution, and the activity also decreased. 相似文献