Disorder effects in the fluorescence spectra of Eu3+ in langatate (La3Ga5.5Ta0.5O14) crystals

The nature of luminescence centers formed by Eu3+ in the partially disordered crystal langatate (La3Ga5.5Ta0.5O14) is investigated using fluorescence spectroscopy. In the low-temperature fluorescence spectra three nonequivalent luminescent centers can be evidenced. This fact can be explained considering the perturbations induced at the Eu3+ site by the nonequivalent configurations produced by Ga3+ and Ta5+ randomly placed in the nearest two octahedral positions.