Microwave-activated formation of lattice defects in alumina polycrystals consolidated by spark plasma sintering

A wet-chemical synthesis and microwave calcination approach was found to be efficient for synthesizing α-alumina powders and polycrystals with high levels of lattice defects. The defects of the as-produced powders were determined from the optical transmittance of spark-plasma-sintered compacts with an identical microstructure using a conventional calcination method. The existence of a high lattice defect concentration was verified by positron annihilation lifetime analysis and X-ray diffraction. The microwave-activated lattice defect phenomenon has potential applications in the production of semiconductor materials or films with high chemical activity or crystal doping.