Influence of B₂O₃ doping on synthesis of MgTiO₃ ceramics from recycled magnesia-hercynite materials

Abstract Herein, magnesium metatitanate (MgTiO₃) ceramics were synthesised using recycled magnesia-hercynite (MH) bricks as the raw materials to achieve solid waste reusing of cement kiln refractories. The recycled MH materials were mixed with anatase TiO₂ to investigate the effect of addition of doped B₂O₃ during the synthesis of MgTiO₃ ceramics at 1400 °C. Phase compositions and microstructural studies were performed using x-ray diffraction (XRD) and scanning electron microscope (SEM), respectively. In addition, energy-dispersive spectroscopy (EDS) was conducted and the dielectric properties of the samples were studied. Results show that the addition of B₂O₃ can promote sintering, improve shrinkage, promote densification, stabilise MgTiO₃ lattice, and inhibit the formation of MgTiO₃. In addition, the presence of appropriate amount of B₂O₃ can accelerate the material diffusion and result in grain growth through the formation of intercrystalline liquid phase. Results also suggest that an increase in dielectric constant results in a decrease in dielectric loss. It was concluded that 2 wt% was the optimum amount of B₂O₃ required to obtain the most favourable synthesis rate of MgTiO₃ (98.2%). The samples exhibited a maximum density of 3.69 g·cm⁻³ and excellent microwave dielectric properties at ε _r = 18.28 and tanδ = 0.086.