Microstructure and optical properties of transparent alumina

Effects of the nature of the doping salt and of the thermal pre-treatment and sintering temperature on Spark Plasma Sintering of transparent alumina

“…The grain size and the transparency of the pure alumina sintered at 1230 8C are in good agreement with the results found by Kim et al [18]. When the temperature was decreased to 1150 8C, the transparency was improved in the visible range but decreased in the IR corroborating our results at 1180 8C.…”

“…However, these measurements were taken at the centre of the pellets. According to the same authors [18], rapid grain growth occurs in the centre of 30 mm diameter pellets compared to the outer part, probably resulting in inhomogeneous transparency of the samples. Decreasing the temperature is beneficial for a decrease in grain size and thus an increase in the RIT.…”

“…SPS is a processing technique that has been widely used over the past decades [1,5,[17][18][19][20]. It was shown that dense, finegrained materials can be developed at low temperatures and short sintering times compared to conventional techniques such as hot isostatic pressing (HIP).…”

High-pressure spark plasma sintering of MgO-doped transparent alumina

“…In addition, our previous study reported that grain growth in the high-density region is accompanied by pore growth. 3) It is considered that the accelerated grain/pore growth at 1200°C made the alumina opaque, despite the high-pressure sintering.…”

“…The rapid grain growth in the inside region was also observed in our previous experiments for pure alumina. 3) Though the rapid grain growth in the inside region must be related to high grain-boundary mobility, the identification of the relating mechanisms are difficult at this moment and detailed examination is required.…”