The Experts below are selected from a list of 118950 Experts worldwide ranked by ideXlab platform
Yoshio Bando - One of the best experts on this subject based on the ideXlab platform.
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conversion of a 2d lepidocrocite type layered Titanate into its 1d nanowire form with enhancement of cation exchange and photocatalytic performance
Inorganic Chemistry, 2019Co-Authors: Mohamed Esmat, Ahmed A Farghali, S I Eldek, M H Khedr, Yusuke Yamauchi, Yoshio BandoAbstract:Layered Titanates with one-dimensional (1D) shapes have been an important class of nanomaterials due to their combination of 1D and 2D fascinating properties. Among many layered Titanates, lepidocrocite-type layered Titanates have significant advantages such as superior intercalation and exfoliation properties, while the synthesis of the 1D-shape forms is still challenging. Here, we report on a facile one-pot hydrothermal conversion of a lepidocrocite-type layered Titanate into the corresponding nanowire-shape form. The reaction mechanism involves the decomposition of the starting layered Titanate into 1D small segments which assemble into the nanowire. This new nanowire shows properties resulting from the combination of 1D and 2D nanostructural features, excellent cation exchange ability, and high photoinduced charge separation and photocatalytic efficiency. As a demonstration, we evaluate the nanowire as a sequestrating material capable of collecting toxic cations, like Cd, from water and photoreducing them (immobilizing them tightly). We find that the nanowire shows an efficient and ultrafast photoimmobilization activity, whereas the starting layered Titanate and a benchmark TiO photocatalyst (P25) show no activity under the identical conditions. The photoimmobilization rate (within 1 min) is considerably faster than the cation exchange rates reported for state-of-the-art cation exchangers (with no photoimmobilization ability). The nanowire used for photoimmobilization reactions is easily recovered from water by decantation, showing the possible practical use for safe disposal of toxic cations in the environment.
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structural features of Titanate nanotubes nanobelts revealed by raman x ray absorption fine structure and electron diffraction characterizations
Journal of Physical Chemistry B, 2005Co-Authors: Katsutoshi Fukuda, Takayoshi Sasaki, Minoru Osada, Yoshio BandoAbstract:High-purity nanotubes and nanobelts could be controllably obtained in hydrothermal treatments of anatase TiO2 in concentrated NaOH solution depending on treating temperature and duration. Their structural features were studied employing X-ray diffraction, Raman, X-ray absorption fine structure, and electron diffraction characterizations. The results reveal that both the nanotubes and nanobelts might be of layered Titanate structure. The similarity and difference among the nanotubes/nanobelts and other bulk Titanates represented by triTitanate H2Ti3O7 and lepidocrocite-type H0.7Ti1.825□0.175O4.0·H2O were also presented.
Mitsuru Itoh - One of the best experts on this subject based on the ideXlab platform.
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enhanced piezoelectricity around the tetragonal orthorhombic morphotropic phase boundary in na k nbo3 atio3 solid solutions
Journal of Electroceramics, 2008Co-Authors: Rongping Wang, Tadashi Sekiya, Hanako Bando, Hirofumi Kawanaka, Koji Matsusaki, Kotaro Hanada, Mitsuru ItohAbstract:The high density perovskite Titanates-modified potassium–sodium niobate solid solutions (1−x)(Na0.5K0.5)NbO3−xBaTiO3 and (1−x)(Na0.5K0.5)NbO3−xSrTiO3 have been prepared by the solid state reaction method. The phase diagram summarized from the dielectric property measurement reveals that there exists a tetragonal/orthorhombic morphotropic phase boundary for both the solid solutions. The piezoelectric properties show enhanced behavior at around the tetragonal/orthorhombic morphotropic phase boundary. It is believed that the origin for the high piezoelectric performance (Na,K)NbO3-based lead-free piezoelectric ceramics is the same as that for the lead zinc niobate-lead Titanate solid solution.
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Enhanced piezoelectricity around the tetragonal/orthorhombic morphotropic phase boundary in (Na,K)NbO3–ATiO3 solid solutions
Journal of Electroceramics, 2008Co-Authors: Rongping Wang, Tadashi Sekiya, Hanako Bando, Hirofumi Kawanaka, Koji Matsusaki, Kotaro Hanada, Mitsuru ItohAbstract:The high density perovskite Titanates-modified potassium–sodium niobate solid solutions (1−x)(Na0.5K0.5)NbO3−xBaTiO3 and (1−x)(Na0.5K0.5)NbO3−xSrTiO3 have been prepared by the solid state reaction method. The phase diagram summarized from the dielectric property measurement reveals that there exists a tetragonal/orthorhombic morphotropic phase boundary for both the solid solutions. The piezoelectric properties show enhanced behavior at around the tetragonal/orthorhombic morphotropic phase boundary. It is believed that the origin for the high piezoelectric performance (Na,K)NbO3-based lead-free piezoelectric ceramics is the same as that for the lead zinc niobate-lead Titanate solid solution.
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candidate compounds with perovskite structure for high lithium ionic conductivity
Solid State Ionics, 1994Co-Authors: Yoshiyuki Inaguma, Mitsuru Itoh, Liquan Chen, Tetsurō NakamuraAbstract:Abstract Compounds with perovskite structure which were candidates for high ionic conductivity were searched and synthesized on the basis of the knowledge of lanthanum lithium Titanates and their ionic conductivity was investigated. The free volume for lithium ions to migrate, and the lithium and vacancy concentrations on the A-site play important roles for the ionic conductivity in the perovskite structure. Lanthanum lithium Titanate substituted with 5 mol% Sr had a larger free volume and showed higher ionic conductivity of the bulk part ( σ =1.5×10 −3 S cm −1 at 300 K) than the pure lanthanum lithium Titanate.
Mohamed Esmat - One of the best experts on this subject based on the ideXlab platform.
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conversion of a 2d lepidocrocite type layered Titanate into its 1d nanowire form with enhancement of cation exchange and photocatalytic performance
Inorganic Chemistry, 2019Co-Authors: Mohamed Esmat, Ahmed A Farghali, S I Eldek, M H Khedr, Yusuke Yamauchi, Yoshio BandoAbstract:Layered Titanates with one-dimensional (1D) shapes have been an important class of nanomaterials due to their combination of 1D and 2D fascinating properties. Among many layered Titanates, lepidocrocite-type layered Titanates have significant advantages such as superior intercalation and exfoliation properties, while the synthesis of the 1D-shape forms is still challenging. Here, we report on a facile one-pot hydrothermal conversion of a lepidocrocite-type layered Titanate into the corresponding nanowire-shape form. The reaction mechanism involves the decomposition of the starting layered Titanate into 1D small segments which assemble into the nanowire. This new nanowire shows properties resulting from the combination of 1D and 2D nanostructural features, excellent cation exchange ability, and high photoinduced charge separation and photocatalytic efficiency. As a demonstration, we evaluate the nanowire as a sequestrating material capable of collecting toxic cations, like Cd, from water and photoreducing them (immobilizing them tightly). We find that the nanowire shows an efficient and ultrafast photoimmobilization activity, whereas the starting layered Titanate and a benchmark TiO photocatalyst (P25) show no activity under the identical conditions. The photoimmobilization rate (within 1 min) is considerably faster than the cation exchange rates reported for state-of-the-art cation exchangers (with no photoimmobilization ability). The nanowire used for photoimmobilization reactions is easily recovered from water by decantation, showing the possible practical use for safe disposal of toxic cations in the environment.
D. A. Payne - One of the best experts on this subject based on the ideXlab platform.
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Extended x-ray absorption fine structure determination of local structure in sol-gel-derived lead Titanate, lead zirconate, and lead zirconate Titanate
Journal of Materials Research, 1995Co-Authors: S. S. Sengupta, D. L. Adler, D. A. PayneAbstract:We report on extended x-ray absorption fine structure (EXAFS) measurements for partially heat-treated gels in the lead zirconate Titanate system (PZT). Self-consistent results obtained from the titanium and zirconium K -edges and the lead L _Ill-edge were used to determine bonding pathways between cations. For lead titantate (PT) and PZT gels, separate networks of predominantly Ti-O-Ti, Zr-O-Zr, and Pb-O-Pb linkages were observed. For lead zirconate (PZ) gels, both Zr-O-Pb and Zr-O-Zr linkages were observed. The results indicate heterogeneity at the molecular level. These findings are discussed in terms of the evolution of structure for PZT materials prepared by our sol-gel method.
Pavel Chráska - One of the best experts on this subject based on the ideXlab platform.
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Dielectric relaxation in calcium Titanate-containing ceramics prepared by plasma spraying
Ceramics International, 2003Co-Authors: Pavel Ctibor, Josef Sedláček, Karel Neufuss, Pavel ChráskaAbstract:Abstract The relative permittivity and loss factor frequency dependence in a weak electric field of plasma sprayed perovskite and ilminite polycrystalline ceramic materials—pure synthetic calcium Titanate, as well as magnesium Titanate—calcium Titanate mixture, were studied. It was observed that plasma-sprayed Titanates exhibit a strong relaxation of permittivity and loss factor decrease when they are measured in an as-sprayed state. The frequency dependence of the earlier properties is influenced by chemical composition and spraying parameters, but the relaxation character in general is preserved in all cases. The volume resistivity of the samples in an as-sprayed as well as subsequently annealed state was studied also. Several aspects of the structural features of plasma deposits and their possible influence on dielectric properties are discussed.
