Temperature dependent polarized Raman spectra of nonaaqualanthanoid (Pr) single crystal.

ABSTRACT

Polarized Raman spectral changes with respect to temperature were investigated for Pr(BrO3)3.9H2O single crystals. FTIR spectra of hydrated and deuterated analogues were also recorded and analysed. Temperature dependent Raman spectral variation have been explained with the help of the thermograms recorded for the crystal. Factor group analysis could propose the appearance of BrO3 ions at sites corresponding to C3v (4) and D3h (2). Analysis of the vibrational bands at room temperature confirms a distorted C3v symmetry for the BrO3 ion in the crystal. From the vibrations of water molecules, hydrogen bonds of varying strengths have also been identified in the crystal. The appearance upsilon1 mode of BrO3- anion at lower wavenumber region is attributed to the attachment of hydrogen atoms to the BrO3- anion. At high temperatures, structural rearrangement is taking place for both H2O molecule and BrO3 ions leading to the loss of water molecules and structural reorientation of bromate ions causing phase transition of the crystal at the temperature of 447 K.