Crystallization and electrical measurements of sintered qandilite (Mg2TiO4)-borosilicate glass composite

Abstract

AbstractQandilite Mg2TiO4 ceramic was prepared from MgO-TiO2 powder/borosilicate glass composite. Composite materials were prepared by nominal MgTiO3 alone and with 10, 30, and 50% borosilicate glass. The sintering process resulted in qandilite alone either in nominal Mg2TiO4 alone or with 10% glass. Incorporation of 30% and 50% glass gave crystalline magnesium titanate (MgTi2O5) in both sintered samples with either forsterite (Mg2SiO4) in 30% containing glass or rutile (TiO2) and enstatite (MgSiO3) in 50% containing glass. The microstructure of sintered samples presented clear tetragonal or octahedral which referred to qandilite in the case of nominal MgTiO3 alone or that containing 10% glass. Also, the later crystals appeared in the case of 70% glass-containing samples whereas in the case of 50% containing glass, in addition to the later clear crystals, rod-like crystals were embedded in glassy matrix. The dielectric constant of the studied composite samples was decreased with increasing the glass fraction until 30 wt%, and then increased to lead to the highest values of dielectric constant (⁓125 at room temperature and 1 kHz) at a glass fraction of 50 wt%. The activation energy (Ea) attained values in the range 0.145–0.438 eV. The results of Ea values and AC conductivity may indicate the dominance of electronic mechanism over the ionic transfer one in the studied sample. The prepared composite samples exhibited a semiconducting nature.