skip to main content

Title: The superionic phase transitions in (NH{sub 4}){sub 3}H(SeO{sub 4}){sub 2} under hydrostatic pressure up to 400 MPa

The effect of hydrostatic pressure on proton conductivity of (NH{sub 4}){sub 3}H(SeO{sub 4}){sub 2} superionic crystal was studied in a wide temperature range and different isobaric conditions by means of impedance spectroscopy method. The measurements were performed along the trigonal c axis of the crystal, i.e., along the direction perpendicular to the plane in which, in the superionic phases, a dynamically disordered H-bond network is formed. The obtained pressure-temperature phase diagram is linear with increasing pressure. The triple point, which is the point of coexistence of the three phases: ferroelastic phase IV, ferroelastic phase III, and superionic phase II was found at p = 116.3 MPa and T = 287.3 K. High pressure leads to increase in the temperature range of stability of both superionic phases and to a drastic decrease in the temperature width of the ferroelastic phase III. With increasing pressure, the range of the superionic phase II expands at the expense of the range of the ferroelastic phase III, which is unstable and vanishes at the triple point.
Authors:
; ; ;  [1]
  1. Institute of Molecular Physics, Polish Academy of Sciences, M. Smoluchowskiego 17, Poznań 60-179 (Poland)
Publication Date:
OSTI Identifier:
22308145
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 116; Journal Issue: 16; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; AMMONIUM COMPOUNDS; CRYSTALS; HYDROGEN COMPOUNDS; IMPEDANCE; PHASE DIAGRAMS; PHASE TRANSFORMATIONS; PRESSURE RANGE MEGA PA 100-1000; PROTON CONDUCTIVITY; SELENATES; SPECTROSCOPY; STABILITY; TEMPERATURE DEPENDENCE; TEMPERATURE RANGE; TRIPLE POINT