摘要:

The swelling of a layered protonic titanate H0.7Ti1.825□0.175O4· H2O (□:vacancy) upon contact with the system of tetrabutylammonium (TBA) ion and H2O has been studied by X-ray diffraction. The TBA-intercalated titanate revealed three distinct gallery heights of 1.47, 1.75 and 2.1 nm, depending on water vapor pressure and drying temperature. These are attributable to crystalline swelling, i. e., zero-, mono-and bi-layer hydrates.

ISSN:1058-725X    

DOI:10.1080/10587259808042419

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

New intercalation compounds, AgxIwBi2Sr2Can-1CuaOy(0.75 <x< 1.2, n = 1 2, and 3) have been prepared by the stepwise intercalation of I and Ag into the layered high-Tcsuperconductor, Bi2Sr2Can-1CunOy. For all three cases (n = 1, 2, and 3), powder XRD analysis indicated that the Ag-I intercalation expanded the [Bi-O]2double slabs within host block by ∼7.3 Å, with subtle changes in physical properties of the pristine. From the Fourier 1-dimensional electron density mapping and the extended X-ray absorption fine structure (EXAFS) analysis to configure the interlayer structure of AgxIw, sublattice, it was revealed that the two-dimensional AgxIwspecies retained a similar iodine skeleton as found in β-AgI, but with a slightly distorted Ag+position. The Ag+ionic conductivity of AgxIwBi2Sr2Can-1CuaOywas turned out to be comparable with that of well known superionic conductors.

ISSN:1058-725X    

DOI:10.1080/10587259808042420

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

A series of layered perovskite oxides, LiLnTa2O7(Ln˭La, Nd and Sm) was prepared by ion-exchange reaction of RbLnTa2O7powders with molten salt of LINO3. According to Rietveld analysis, it is found that the tantalum ions are remarkably displaced from the center of TaO6octahedra, resulting in a short Ta-Oapexbond due to high covalent bonding character. On replacing the large constituting ion in Ln site with smaller one, TaO6octahedron becomes more distorted, which gives rise to a remarkably shorter Ta-Oapexbond An increasing trend of Ta-Oepexbond strength observed by Raman spectra is well consistent with the reverse trend of Ta-Oapexbond distance from the Rietveld analysis. As the large La ion is replaced by the smaller one (from La to Nd, Sm), the ionic conductivity increases with a decrease of activation energy It is therefore concluded that the strong Ta-Oapexbond leads to a weakening of Li-Oapexbond in view point of bond competition, giving rise to an enhancement of Li ion conduction.

ISSN:1058-725X    

DOI:10.1080/10587259808042421

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

In this work we report on the intercalation of single crystals of Bi2Sr2CaCu2O8with iodine to form the stage-1 intercalated complex IBi2Sr2CaCu2O8, and on the electrical resistivity of this final product, both as a function of temperature,T, (between 10 K and 300 K) and magnetic field,H, (going up to 15 T). Both ρab, the resistivity in theab-plane, and ρc, the resistivity along thec-axis have been studied forH // abandH // c. We find that the metallic character of electrical conduction along the c-axis observed in the normal state in intercalated samples (as compared with the semiconducting character in the pristine host) is maintained when a magnetic field is applied, confirming that, in the normal state, a reduction in the anisotropy accompanies the intercalation process. In the superconducting state, however, we find that the magnetic field causes a broadening of the superconducting transition (as in non-intercalated Bi2Sr2CaCu2O8), especially whenH // c, indicating that the superconducting state retains a highly anisotropic character after intercalation. The resistivity data in the flux-flow regime have also allowed us to estimate values of the activation energy for vortex movement.

ISSN:1058-725X    

DOI:10.1080/10587259808042422

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The present work is aimed at investigating hydrogen transport through amorphous WO3(a-WO3) and crystalline WO3(c-WO3) films prepared by rf-magnetron sputtering onto indium tin oxide(ITO) glass under impermeable boundary condition in 0.1 M H2SO4solution by using Fourier transform infra-red(FTIR) spectroscopy, cyclic voltammetry, potentiostatic current transient technique and ac-impedance technique. The FTIR spectra showed that thea-WO3film contained water, apart from thec-WO3. From the results obtained form the electrochemical experiments, it was suggested that the different behaviours in cyclic voltammograms betweena-andc-WO3films result from an open-structured nature ofa-WO3film containing H2O, which does not exist in thec-WO3film and there are three kinds of hydrogen injection sites in the films, i.e., reversibly active site, shallow trap site(reversible trap site) and deep trap site(irreversible trap site). The Mott-Schottky approach permitted us to semi-quantitatively determine the amount of the deep trap site.

ISSN:1058-725X    

DOI:10.1080/10587259808042423

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

I would first of all like to express the thanks of all the participants to the Local Organizing Committee for the truly magnificent work of preparation that preceded ISIC 9. For this job, particularly well done, thank you.

ISSN:1058-725X    

DOI:10.1080/10587259808042424

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

ISSN:1058-725X    

DOI:10.1080/10587259808042358

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor