Optical spectroscopy of a chromium doped (CH3)2NH2Al(SO4)2·6H2O single crystal in the ferroelectric phase

The chromium doped (CH3)2NH2Al(SO4)2·6H2O crystal was obtained from solution by a slow evaporaion method at 303 K and investigated in the ferroelectric phase below 150 K using optical spectroscopy. It was found that the Cr3+ ions in the crystal are situated in a strong crystal field in which the 2E state is the lowest. A single narrow R line associated with the 2E−4A2 phosphorescence indicates an undistorted octahedral Cr3+ site in the host lattice. The OH bonds in the first coordination sphere induce efficient nonradiative transitions from the 2E emitting state and the Cr3+ emission is completely quenched at temperatures above 150 K.