Structural and dielectric comparative studies of geopolymers prepared with metakaolin and Tunisian natural clay

Metakaolin and calcined Tunisian natural clay were used as potential aluminosilicate sources to synthesize phosphoric acid - inorganic polymers known as geopolymers. Structural and dielectric properties of these two kinds of clay were studied. X-ray diffraction patterns showed that the main phases presented for both clays were quartz and illite. Besides, these two specimen showed a great similarity in their dielectric properties in a frequency range [10(2)-10(6)] Hz. Nevertheless, a dissimilarity was observed at low frequencies [1-10(2)] Hz as a result of the difference in their mineral compositions. In a second time, a comparative study between two geopolymers made of metakaolin and the calcined natural clay was realized. New crystalline phases, produced during geopolymerization reaction were detected in both geopolymers X-ray diffraction patterns. Dielectric results revealed a difference in their dielectric parameters in the low frequency range. It resulted from a variation in charge distribution into the two geopolymer structures. However, for high frequencies a great similarity was observed for both geopolymers. (C) 2017 Elsevier B.V. All rights reserved.