Superprotonic Phase Transition in CsH(PO_3H)
Abstract
High-temperature investigations of the compound CsH(PO₃H) (or CsH₂PO₃, cesium hydrogen phosphite) revealed that this material undergoes a transition, with an onset of 137 °C, to a phase of high proton conductivity. The transition is accompanied by a large heat of transformation, ΔH = 58 ± 2 J/g (12.4 ± 0.4 kJ/mol), and exhibits measurable hysteresis, occurring at 96 °C upon cooling. High-temperature X-ray powder diffraction showed that the high-temperature phase is cubic, with a₀ = 4.896(1)Å, and likely takes on a CsCl structure, with Cs atoms at the corners of a simple cubic unit cell, and PO₃H groups at the center. The conductivity in the high-temperature phase at 160 °C is 5.5 × 10⁻³ Ω⁻¹ cm⁻¹, and the activation energy for proton transport is 0.40 ± 0.01 eV. These values suggest that proton transport is facilitated by rapid PO₃H group reorientations in the cubic phase of CsH(PO₃H), as is known to occur in the high-temperature, tetragonal phase of CsHSO₄.
Additional Information
Copyright © 2002 American Chemical Society. Received March 27, 2002. Revised Manuscript Received June 19, 2002. Publication Date (Web): August 23, 2002. CM020297V. We are pleased to acknowledge the financial support of the National Science Foundation. Additional funding was provided by the Irvine Foundation.Additional details
- Alternative title
- Superprotonic Phase Transition in CsH(PO3H)
- Eprint ID
- 42713
- DOI
- 10.1021/cm020297v
- Resolver ID
- CaltechAUTHORS:20131125-162531441
- NSF
- Irvine Foundation
- Created
-
2013-11-27Created from EPrint's datestamp field
- Updated
-
2023-10-25Created from EPrint's last_modified field