Structural and spectroscopic properties of MgAl2O4:Nd3+ transparent ceramics fabricated by using two-step Spark Plasma Sintering

Neodymium-doped magnesium aluminate spinel Nd3+:MgAl2O4 transparent ceramics were successfully elaborated with significant Nd content (i.e. up to 0.2 at.%) by using Spark Plasma Sintering (SPS). Microstructural, structural, and optical properties of the obtained samples were compared to those of undoped transparent spinel ceramics. The transparency is of about 70% in the visible region for undoped samples and of about 50% for neodymium-doped samples with a significant shift of the cut-off wavelength in UV region to higher values. Spectroscopic measurements have evidenced the formation of charge-compensating structural defects owing to Mg2+ substitution by Nd3+ in the spinel crystalline lattice. Nd3+ ions were incorporated up to 0.2 at.% in spinel crystalline lattice, largely higher than that possible in MgAl2O4 single-crystals. SPS thus appears as an appropriate technique to manufacture transparent materials with out-of-equilibrium structure and composition.