Abstract
Optimum spark-plasma-sintering processing was examined in order to fabricate transparent spinel polycrystal. For a low heating rate of 10C/min, in-line transmission T of spinel polycrystal depends strongly on sintering temperature, particular in visible-wavelength ranges. For a infrared-wavelength of 2000nm, T(2000) attains 60-70% irrespective of temperature. For a visible-wavelength of 550nm, however, T(550) varies from 2 to 50% depending on sintering temperature; T(550) shows a peak value of about 50% at around 1300C. The temperature dependent in-line transmission can be ascribed to the change in microstructure such as grain size, resultant residual porosity and the precipitation of MgO phase.
