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In this work we present a detailed study of the temperature evolution (290 K–20 K) of the polarized Raman spectra in a single crystal of glycinium phosphite. The phase transition manifests itself by the activation of new Raman bands and by the occurrence of anomalies in the temperature dependence of the wavenumber of some external and internal modes. The results show that occurring deformations in molecular units contribute relevantly to the spontaneous polarization in GPI. The anomalous behaviour of the wavenumber and of the damping constant of some bands is in good agreement with a theoretical model based in a pseudospin-phonon interaction. [ABSTRACT FROM AUTHOR]

Betaine calcium perchlorate monohydrate (here designate by BCPM) is a new compound of the amino acid betaine with a triclinic symmetry and with the space group P..., at room temperature. In this work we present a detailed study of dielectric properties and of Raman scattering spectra of BCPM, which disclose interesting structural changes in the temperature range 20 K-300 K. [ABSTRACT FROM AUTHOR]