Comparative study of the phase transitions and spectral properties of NH2(CH3)2Me1-Ñ Ð¡rx(SO4)2×6H2O (Me = Al, Ga) ferroelectrics

This article is devoted to study of Cr3+ ion complexes in NH2(CH3)2Me1-xCrx(SO4)2 × 6H2O, Me = Al, Ga (DMAMe1-xCrxS) crystals. On the basis of spectroscopic data the energy diagram and the parameters of the crystal field corresponding to the above mentioned complexes were specified. It was shown that isomorphous substitution of the metal ion practically does not affect the temperature of ferroelectric-ferroelastic phase transition in NH2(CH3)2Ga1-xCrx(SO4)2 × 6H2O contrary to the case of NH2(CH3)2Al1-xCrx(SO4)2 × 6H2O crystal. The structure and temperature changes of the absorption spectra of the above mentioned solid solutions are explained in terms of the internal electronic transitions in [Сr(H2O)6]3+ octahedral complexes. The symmetry and distortion of the complexes within the structure of all investigated crystals were analyzed on the basis of the Raman spectroscopy data.