Raman scattering spectra of internal modes of ferroelectric deuterated dicalcium strontium propionate, ca₂sr(c₂d₅co₂)₆

Abstract

The Raman scattering spectra of the ferroelectric DDSP (deuterated dicalcium strontium propionate. Ca₂Sr(C₂D₅Co₂)₆) crystal have been observed at room temperature in the frequency range up to 4000 cm⁻¹. The modes of the internal vibration have been assigned by comparison with the frequency shift of the non-deuterated crystal Ca₂Sr(C₂H_5CO₂)₆ (DSP) and also with the spectra of the D₂O or H₂O solution of these crystals. The effect of the deuteration is confirmed as decrease of the frequency of the several internal modes of the propionic radical C₂D₅COO⁻; the CH₃ symmetric bending mode at 1380 cm⁻¹ shifts to 1058 cm⁻¹ indicating increase of the molecular moment of inertia. A minor role is suggested for the motion of the propionate molecule as a trigger for the phase transition mechanism.