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

Abstract 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.