title: Polarised vibrational spectra of betaine ortho-phosphoric acid complex. Part II. Phase transitions studies.
abstract: Polarised infrared transmission and Raman spectra of betaine ortho-phosphoric acid crystal in temperature ranges 13-393 and 13-300 K, respectively are reported and discussed in relation to phase transitions: antiferrodistortive at T(c1) = 365 K and antiferroelectric at T(c3) = 81 K. The spectra are consistent with unit cell doubling below T(c3). The participation of all hydrogen bonds apparent in the crystal in the antiferroelectric phase transition was shown. Quite large freedom of -N(CH(3))(3) groups reorientation in the antiferroelectric phase was detected. No changes were found in the transmission spectra taken in the vicinity of the antiferrodistortive phase transition temperature.
authors.affiliation: Faculty of Chemistry, Wrocław University, 50-383 Wroclaw, Joliot Curie 14, Poland. mai@wchuwr.chem.uni.wroc.pl
authors.forename: Maria M
authors.initials: MM
authors.lastname: Ilczyszyn
mesh_terms: D001622:Betaine / Q000737:chemistry*; D044367:Phase Transition; D010756:Phosphoric Acids / Q000737:chemistry*; D013055:Spectrophotometry, Infrared; D013059:Spectrum Analysis, Raman
chemical_list: D010756:Phosphoric Acids; D001622:Betaine