Microscopic Theory of Rb_{1 - x}(NH₄)_xH₂PO₄Type Compounds

Abstract

We propose a pseudospin model for the Rb 1−x (NH 4 ) x H 2 PO 4 type proton glasses, which takes into account energy levels of hydrogens near a PO 4 group (within a cluster approximation), long-range interactions between the hydrogen bonds, and an internal random deformational field. Relaxation is explored within the framework of the Glauber dynamics. We obtain a qualitative description of temperature behavior of the state parameters and dielectric permittivities of Rb 1−x (ND 4 ) x D 2 PO 4 compounds at different frequencies.

Диэлектрические, электромеханические и упругие свойства монокристаллов Rb-=SUB=-1-x-=/SUB=-(NH-=SUB=-4-=/SUB=-)-=SUB=-x-=/SUB=-H-=SUB=-2-=/SUB=-PO-=SUB=-4-=/SUB=-

“…Позже была развита кластерная теория для описания тер-модинамических и динамических свойств систем типа Rb 1−x (NH 4 ) x H 2 PO 4 [5][6][7][8][9], которая при надлежащем вы-боре параметров позволила удовлетворительно описать диэлектрические и поляризационные свойства этих ма-териалов без учета пьезоэлектрической связи. Вместе с тем необходимость такого учета следует из анализа ряда работ.…”

Thermodynamics, dielectric permittivity and phase diagrams of the Rb_{1-x}(NH_{4})_{x}H_{2}PO_{4} type proton glasses

“…The temperature dependence of transverse permittivity for the Rb 1−x (ND 4 ) x D 2 PO 4 and Rb 1−x (NH 4 ) x H 2 AsO 4 compounds was explored in previous papers [82,83].…”

“…In [82,83] a similar approach has been used for the description of some thermodynamic characteristics and transverse dielectric permittivity of hydrogen bonded Rb 1−x (ND 4 ) x D 2 PO 4 and Rb 1−x (NH 4 ) x H 2 AsO 4 compounds, in which an essential role in the formation of energy levels is played by the proton short-range correlations. The goal of the present paper is to calculate the thermodynamic characteristics, the longitudinal and transverse dielectric permittivities of these compounds at different temperatures, concentrations, and frequencies, as well as to determine their phase diagrams.…”

“…In [78][79][80][81] a theory of static characteristics of model proton glasses with an arbitrary range of competing interactions has been proposed. In [82,83] a similar approach has been used for the description of some thermodynamic characteristics and transverse dielectric permittivity of hydrogen bonded Rb 1−x (ND 4 ) x D 2 PO 4 and Rb 1−x (NH 4 ) x H 2 AsO 4 compounds, in which an essential role in the formation of energy levels is played by the proton short-range correlations.…”

Features of the behavior of longitudinal static and dynamic dielectric, piezoelectric, and elastic characteristics of KH2PO4 and NH4H2PO4 crystals

“…In addition, a cluster theory of the thermody namic and dynamic behavior of compounds of the Rb 1 -x (NH 4 ) x H 2 PO 4 type was developed in [9][10][11][12][13]. If the parameters are selected properly, the theory describes experimental data in terms of quantity fairly well.…”