title: Quantum paraelectricity in KD2PO4 and KH2PO4 under high pressure.
abstract: Phase transition temperatures of hydrogen-bonded ferroelectrics DKDP ( KD2PO4) and KDP ( KH2PO4) vanish at pressure p larger than respective critical pressures p(c). The dielectric constants epsilon(c) has been observed to be suppressed with decreasing temperature for p>p(c) and analyzed as the quantum paraelectricity by fitting with the Barrett formula in terms of three parameters. The dependences of the three parameters on p-p(c) are found to be expressed by almost similar lines, and the phase transition mechanism near p(c) is explained from the viewpoint of an anharmonic phonon system in KDP and DKDP.
authors.affiliation: Research Center for Material Science at Extreme Conditions, Osaka University, Toyonaka, Osaka 560-8531, Japan.
authors.forename: Shoichi
authors.initials: S
authors.lastname: Endo
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Deguchi
authors.forename: Masaharu
authors.initials: M
authors.lastname: Tokunaga