Photoluminescent characterization of atomic diffusion in core-shell nanoparticles

Eu3+ doped LaF3 nanoparticles with core/shell morphologies were synthesized and selected spectroscopic properties were measured as a function of heat treatment times and temperatures. More specifically, the relative intensity of photoluminescence spectra, both through direct excitation of the lanthanide as well as phonon sideband spectra were evaluated with increasing amounts of time held at specific temperatures. A one dimensional approximation was used to compute an effective diffusion coefficient for the rare earth dopants in LaF3. Despite the simplicity of the model employed, the calculated diffusion coefficients based on the spectroscopic results are accurate within an order of magnitude in comparison to other fluoride crystals yielding a simplified approach to estimating kinetic and diffusion effects in optical materials.