Both DC and AC resistivities of some silicate glass fibres containing 10 to 30 mol.% sodium and subjected to a sodium to or from silver ion-exchange treatment have been investigated. Ion-exchanged fibres exhibit resistivity and activation energy values lower than those of the untreated ones. A suitable combination of temperature and electric field brings about a further semi-permanent reduction in resistivity and activation energy values. Typical values of room temperature resistivity and activation energy in this high conducting state are approximately 50 Omega cm and 0.04 eV respectively. Such behaviour is explained on the basis of formation of an interconnected silver-rich phase under the combined influence of temperature and a suitable electric field. The properties exhibited by these materials are comparable to some of the conventional fast ion conducting glasses containing a higher silver concentration than those in the present system.

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Novel shielding materials for electromagnetic radiations have been formulated using two different approaches using red mud and processed red mud based systems. The crystallographic aspect of multicomponent and multishielding phases, in the formulated shielding materials, on the shielding efficiency has been studied. The formulated shielding materials have been evaluated for radiation attenuation using Co-60 gamma ray irradiation source and were found to reduce the shielding thickness, i.e. half value thickness, to about 40-60% of concrete. The X-ray diffraction studies confirmed the presence of bafertisite, sanbornite, celsian and troilite as the major shielding phases and phosphates of aluminium and iron as the binder phases. The SEM revealed the highly compacted and continued integrated morphological features of various shielding phases. The unique combination of these different phases is responsible for providing bonding to the ceramic matrix leading to the effective shielding and mechanical properties.