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

Qandilite 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 (E_a) attained values in the range 0.145–0.438 eV. The results of E_a 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.