Synthesis and Consolidation of BaAl ₂ Si ₂ O ₈ :Eu: Development of an Integrated Process for Luminescent Smart Ceramic Materials

Abstract

A novel, integrated, fast, and inexpensive process for the preparation of dense Ba (1− x ) Eu x Al 2 Si 2 O 8 thin ceramic specimens for damage sensor applications is reported. The processing approach involves a combination of combustion synthesis for the preparation of the powders and spark plasma sintering (SPS) for the consolidation of the specimens to densities close to 100% of relative density. The synthesis of the porous powders by combustion resulted in particle (agglomerate) sizes that were on average 421 nm, as determined from dynamic light scattering, and in the almost complete reduction of the initial Eu 3+ activators to Eu 2+ . The powders densified to grain sizes of around 250 nm due to a collapse of the porous powder structure and minimal grain growth during SPS. Thermal treatment of the powders and sintered specimens improved the intensity of the emissions at 373 and 745 nm and diminished the emission at 485 nm. The luminescence phenomena from the specimens were a result of two mechanisms: (1) the removal of strain in the lattice due to thermal treatment, and (2) a charge transfer mechanism between Eu 2+ and Eu 3+ .