Energy transfer from tetrahedral Fe3+ sites to Tm3+ in garnets.

Abstract

A very efficient energy transfer from ${\mathrm{Fe}}^{3+}$ (d tetrahedral sites) to ${\mathrm{Tm}}^{3+}$ (c dodecahedral sites) in yttrium aluminum garnet and gadolinium gallium garnet crystals was observed. The site-selective spectroscopy shows that in case of near-neighbor Fe(d)-Tm pairs the transfer efficiency is 100%. For the other pairs it is less efficient and increases with temperature due to a better superposition of ${\mathrm{Fe}}^{3+}$ emission and $^{3}$${\mathit{H}}_{4}$ ${\mathrm{Tm}}^{3+}$ absorption bands.