Papers by Keyword: Porous Glass

Abstract: The influence of the size effect on the features of ADP-KDP-porous glasses composites was studied. The dielectric permittivity results of mixed ADP and KDP embedded into porous glasses with different average pore sizes in a wide temperature range are presented. The data obtained indicate that pore size affects the nature of the dielectric anomaly in the vicinity of phase transition regions.

Abstract: Hydrothermal treatment has been conducted to create porous glass or ceramics as value-added materials for the recycling of slag and glass. Under hydrothermal conditions, slag and glass react with a high pressurized H₂O and hydrate glass phase containing plenty of H₂O is formed to connect raw materials particles to make ceramic materials. The hydrothermal process takes advantages of energy costs, because it can be operated at a low temperature compared to conventional sintering processes. Since the hydrothermal process uses H₂O to fabricate ceramic materials, it can be regarded as energy-saving, eco-friendly, and spontaneous materials processing. In the present study, we introduce some applications of hydrothermal treatments to slag / glass to produce functional porous ceramic materials.

Abstract: Silica aerogels have been studied with the objective of understanding the mechanical behavior of these extremely porous (pore volume higher than 85%) glassy materials. Elastic and plastic behaviors are investigated using Hg porosimetry. Because of the peculiar structure of these materials, Hg liquid cannot enter their porous network and consequently induces an isostatic pressure. Due to the high compliance of the solid network, under isostatic pressure aerogels display an irreversible shrinkage caused by plastic deformation. The magnitude of the plastic shrinkage and the increase of the associated mechanical properties depend on the different parameters (porosity, elastic properties and structural features). The structural features are followed by X Rays scattering. The irreversible compaction can be explained by siloxane bond formation between clusters constituting the porous materials, retaining the strained structure. The pore collapse mechanism is favored by the large pores structure and loose cluster structure (low fractal dimension). This densification process could offer a new way to synthesize porous glasses at room temperature.

Abstract: Positron annihilation lifetime spectroscopy (PALS) is used to study a series of controlled pore glasses (CPG). The lifetime spectra were decomposed into four components using the routine LifeTime, version 9.0 (LT9). The largest lifetime τ4, which is attributed to the annihilation of ortho-positronium (o-Ps) localized at mesopores, varied at 300 K between 21 and 131 ns. The size of mesopores (mean free path), D, was determined by N2 adsorption and Hg intrusion techniques to vary between 1.8 and 56 nm. It is shown that the Tao-Eldrup model extended to cylinders of infinite length and diameter d = D describes well the experiment for an overlap parameter δ fitted to be δ = 0.193 nm. The spectra were also analyzed allowing a distribution of o-Ps lifetimes. A method is developed to calculate the pore size distribution n(d) from the τ4 distribution. This method is of particular interest since PALS is very sensitive to pores being too small to be exactly analyzed by conventional porosimetry.

Abstract: To improve ion mobility in solid inorganic electrolyte for lithium ion battery, the hybrid electrolytes were developed in the form of the organic-inorganic meso-scale hybridization by the infiltration of liquid electrolyte into meso-porous inorganic glass membrane. Glass electrolyte membranes with nanopores were prepared by spinodal decomposition and subsequent acid leaching. The most suitable glass electrolyte membranes could be fabricated from the 7.5Na2O-46.25B2O3 -46.25SiO2 (mol%). The effect of leaching temperature, leaching time and leaching acids on the preparation of the membranes were investigated. The microstructure of the cross-section of 7.5Na2O-46.25B2O3-46.25SiO2 glass electrolytes were examined with a scanning electron microscope. Then, liquid electrolyte was infiltrated by dipping method into etched glasses electrolyte. Full cells were fabricated by LiCoO2 for cathode materials and MCMB for anode materials. Conductivity and charge-discharge test of the porous glass electrolyte membrane was measured.