1 7O NQR study of the antiferroelectric phase transition in TlH2PO4

Abstract

The temperature dependence of the 17O NQR spectra in TlH2PO4 has been measured using a proton-17 O nuclear quadrupole double resonance technique. The results show that the protons in the short one-dimensionally linked O1–H1--O1 and O2–H2--O2 hydrogen bonds are moving between two equilibrium sites above Tc and freeze into one of the off-center sites below Tc. The protons in the asymmetric O3–H3--O4 hydrogen bonds are static and ordered above and below Tc.