摘要:

The NMR pulsed field gradient technique was used to study molecular transport in porous glasses. The adsorbent materials were produced by leaching phase‐separated sodium‐boron‐silica glasses of different composition, then heat‐treating. The pore diameters of the glass samples produced were within the interval 0.8 to 50 nm. Water, methanol, dodecane, and do‐decene were used as adsorbates. The coefficients of adsorbate self‐diffusion were found to decrease with decreasing pore diameter. In comparison with the neat liquids, a reduction in the adsorbate mobility (up to two orders of magnitude) was observed. For the larger pores, that decrease may be attributed to the tortuosity of the adsorbent, whereas the low diffusivities in the porous glasses with small pores are a consequence of the stabilizing effect of the rigid adsorben

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1983.tb09971.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

The structure of a borosilicate glass containing simulated nuclear waste on a distance scale up to several tens of nanometers was investigated using neutron scattering techniques. Comparison of samples with and without waste suggests that the nature of the basic network of SiO4tetrahedra and BO3triangles is largely unchanged by addition of the waste. The real‐space correlation function for the glass plus waste has clear features at distances below 0.5 nm, which can be attributed to the above network building units. Study of a partially devitrified sample shows diffraction effects due to polycrystalline and vitreous phases. Vitreous and partially devitrified glass containing waste produced a significant amount of small‐angle scattering corresponding to regions of inhomogeneity which are 10 nm and lar

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1983.tb09972.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

MgO compacts were sintered from 900° to 1395°C in dry argon and in argon with 2.3 kPa of water vapor. The surface area and pore size distributions measured by mercury porosimetry showed large changes during the first minute of sintering, indicating that rearrangement instead of coalescence of small particles is the controlling process in the early stage. Rearrangement was found to be temperature‐dependent and to extend through the initial stage of sinter

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1983.tb09973.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY