OPTICAL SPECTROSCOPY OF CHROMIUM-DOPED (CH3)(2)NH2X(SO4)(2).6H(2)O (X=AL, GA) SINGLE-CRYSTALS

Chromium doped (CH3)(2)NH2Al(SO4)(2). 6H(2)O (DMAALS) and (CH3)(2)NH2G a(SO4)(2). 6H(2)O (DMAGaS) single crystals were grown and investigated using the methods of optical spectroscopy. It was found that the Cr3 ions in the two crystals are situated in a strong crystal field in wh ich the E-2 State is the lowest. The single narrow R-line associated w ith the E-2-(4)A(2) phosphorescence of Cr3+ in DMAAIS in a ferroelectr ic phase indicates an undistorted octahedral site, whereas important d istortion of Oh symmetry and structural disorder was inferred from spe ctral data obtained with DMAGaS:Cr3+ in a low temperature phase. Resul ts of optical investigation are discussed taking into account the stru ctural data. (C) 1998 Elsevier Science B.V. All rights reserved.