Structure and dynamics of crystal α-modification of potassium biiodate

FT-IR (4000-400 cm−1) and FIR (400-10 cm−1) spectra of α-modification of acid potassium iodate (α-KIO3·HIO3) were measured in the paraelectric (at 300-220 K) and ferroelectric (at 223-20 K) phases. FIR spectra of the ferroelectric phase were found to exhibit doublet structure of many bands while FT-IR spectra mainly remain invariable. The results are in good agreement with the order-disorder mechanism of ferroelectric phase transition connected with localization of the proton within a strong hydrogen bond.