title: One-dimensional correlation in the dipolar Ising crystal tricyclohexylmethanol: crystal structure revisited and heat capacity.
abstract: The crystal structure of an organic weak-ferroelectrics, tricyclohexylmethanol (TCHM), was re-examined by single-crystal x-ray diffraction at room temperature. TCHM forms a dimer through hydrogen bonding at the centre of the dimer, where two hydroxyl groups are arranged in tandem and their direction is disordered in two possible orientations, which brings about a dipolar Ising nature. The heat capacity measured by adiabatic calorimetry from 6 to 400 K shows three anomalies including fusion at 368 K. The entropy of the ferroelectric transition is 1.9 J K(-1) mol(-1), supporting the order-disorder mechanism of dimer dipoles. A broad anomaly at 348 K is related to the breakage of the intra-dimer hydrogen bond. Detailed analysis of the temperature dependence of heat capacity due to the phase transition showed the presence of a broad hump in the excess heat capacity around 160 K. The temperature dependences of the excess heat capacity and the existing dielectric constant can be analysed in terms of a highly anisotropic Ising model.
authors.affiliation: Department of Chemistry, Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8571, Japan.
authors.forename: Yasuhisa
authors.initials: Y
authors.lastname: Yamamura
authors.forename: Hideki
authors.initials: H
authors.lastname: Saitoh
authors.forename: Masato
authors.initials: M
authors.lastname: Sumita
authors.forename: Kazuya
authors.initials: K
authors.lastname: Saito