Time resolved and site selective luminescence of M₂Ln₃Sb₃O₁₄ (M = Mg, Ca): Multisite Eu³⁺ environments

Time resolved and site selective spectra at low temperatures have been recorded for M₂Ln₃Sb₃O₁₄ (M = Mg, Ca) doped with Eu³⁺ at concentrations of 1 and 0.1 at.%. The M = Mg spectra can be interpreted in a model with Eu³⁺ situated at the La³⁺ C_2h (2/m) site, although weaker bands are indicative of antisites at expected nearest La³⁺ neighbours. A minority of the Eu³⁺ ions in the M = Ca system are also situated at C_2h sites, but structural disorder leads to most of the Eu³⁺ ions experiencing more varied spectra and lower site symmetry.