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

Abstract

Herein, magnesium metatitanate (MgTiO _3 ) 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 TiO _2 to investigate the effect of addition of doped B _2 O _3 during the synthesis of MgTiO _3 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 B _2 O _3 can promote sintering, improve shrinkage, promote densification, stabilise MgTiO _3 lattice, and inhibit the formation of MgTiO _3 . In addition, the presence of appropriate amount of B _2 O _3 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 B _2 O _3 required to obtain the most favourable synthesis rate of MgTiO _3 (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 tan δ = 0.086.

Keywords

• recycled magnesia-hercynite bricks
• MgTiO3 ceramic
• B2O3
• solid waste reuse
• dielectric properties