MgAl2O4 spinel with transmittance approaching theoretical value at reduced sintering temperatures.

Magnesium aluminate spinel is known to be a material with a good combination of mechanical properties, resistance against chemical attack and a high melting point, being thus a very promising material for application as a transparent material in harsh, high-temperature environments where glass fails. To improve the control over the microstructural evolution during sintering, Eu3+, Y3+ Mg2+ and their combinations were introduced as doping elements. The goal of the study was to optimize processing of fine spinel powder and investigate the potential for enhancing MgAl 2 O 4 spinel density and in-line transmittance by using elements segregating to grain boundaries. The total and in-line transmittance were measured, and the characteristic pore size for transparent samples calculated based on the Rayleigh scattering approximation. Eu-doping proved to be effective in lowering the residual pore size and thus achieving in-line transmittance approaching the theoretical value at relatively low sintering temperatures (1400 °C). [ABSTRACT FROM AUTHOR]