title: Phase transition and ring-puckering motion in a metal-organic perovskite [(CH2)3NH2][Zn(HCOO)3].
abstract: Phase transitions in a metal-organic perovskite with an azetidinium cation, which exhibits giant polarizability, were investigated using differential scanning calorimetry (DSC) and (1)H nuclear magnetic resonance (NMR) measurements. The DSC results indicated successive phase transitions at 254 and 299 K. The temperature dependence of the spin-lattice relaxation time T(1) determined by NMR indicated that the activation energy for cation ring-puckering motion was 25 kJ mol(-1) in phase I (T > 299 K). The potential energy at the transition state of puckering is expected to decrease when the potential for the motion becomes asymmetric with decreasing temperature in phases II and III. A possible mechanism for the onset of an extraordinarily large dielectric anomaly is discussed.
authors.affiliation: Department of Chemistry, College of Humanities and Sciences, Nihon University, Setagaya-ku, Tokyo, Japan. asaji@chs.nihon-u.ac.jp
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Asaji
authors.forename: Yoshiharu
authors.initials: Y
authors.lastname: Ito
authors.forename: Janez
authors.initials: J
authors.lastname: Seliger
authors.forename: Veselko
authors.initials: V
authors.lastname: Zagar
authors.forename: Anton
authors.initials: A
authors.lastname: Gradišek
authors.forename: Tomaž
authors.initials: T
authors.lastname: Apih