The effect of annealing process on the optical and microwave dielectric properties of transparent MgAl_2O_4 ceramics by spark plasma sintering

摘要

Transparent MgAl_2O_4 ceramics were fabricated by using spark plasma sintering (SPS). The effects of annealing temperature on the optical and microwave dielectric properties were investigated by positron annihilation technique and X-ray photoelectron spectroscopy (XPS). The results showed that the optimal annealing temperature for the optical property improvement was 900 ℃ and the in-line transmittance was improved to 74.9% at the wavelength of 550 nm. The further elevation of annealing temperature damaged the optical performance due to the combination of oxygen vacancies. The Q ×f values of transparent MgAl_2O_4 ceramics were an overall increase from 800 ℃ to 1200 ℃, but decreased at 1300 ℃. It can be concluded that the annealing temperature plays an important role in the Q × f value, while a certain annealing temperature is corresponding to the best microwave dielectric property.