The present invention relates to an article comprising at least one of a glass or glass-ceramic comprising Al2O3 and at least one of REO or Y2O3, wherein at least 60 percent by weight of the glass or glass-ceramic collectively comprise the Al2O3 and the at least one of REO or Y2O3, and wherein the glass or glass-ceramic contains not more than 20 percent by weight SiO2 and not more than 20 percent by weight B2O3, based on the total weight of the glass or glass-ceramic.