Superprotonic Phase Transition in CsH(PO3H)
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- 作者：Calum R. I. Chisholm ; Ryan B. Merle ; Dane A. Boysen ; and Sossina M. Haile
- 刊名：Chemistry of Materials
- 出版年：2002
- 出版时间：September 2002
- 年：2002
- 卷：14
- 期：9
- 页码：3889 - 3893
- 全文大小：160K
- 年卷期：v.14,no.9(September 2002)
- ISSN：1520-5002
文摘
High-temperature investigations of the compound CsH(PO3H) (or CsH2PO3, cesiumhydrogen phosphite) revealed that this material undergoes a transition, with an onset of137 
C, to a phase of high proton conductivity. The transition is accompanied by a largeheat of transformation, 
rs/Delta.gif" BORDER=0 >H = 58 ± 2 J/g (12.4 ± 0.4 kJ/mol), and exhibits measurablehysteresis, occurring at 96 C upon cooling. High-temperature X-ray powder diffractionshowed that the high-temperature phase is cubic, with ao = 4.896(1) Å, and likely takes ona CsCl structure, with Cs atoms at the corners of a simple cubic unit cell, and PO3H groupsat the center. The conductivity in the high-temperature phase at 160 C is 5.5 × 10-3 rs/Omega.gif" BORDER=0 >-1cm-1, and the activation energy for proton transport is 0.40 ± 0.01 eV. These values suggestthat proton transport is facilitated by rapid PO3H group reorientations in the cubic phaseof CsH(PO3H), as is known to occur in the high-temperature, tetragonal phase of CsHSO4.
C, to a phase of high proton conductivity. The transition is accompanied by a largeheat of transformation, rs/Delta.gif" BORDER=0 >H = 58 ± 2 J/g (12.4 ± 0.4 kJ/mol), and exhibits measurablehysteresis, occurring at 96 C upon cooling. High-temperature X-ray powder diffractionshowed that the high-temperature phase is cubic, with ao = 4.896(1) Å, and likely takes ona CsCl structure, with Cs atoms at the corners of a simple cubic unit cell, and PO3H groupsat the center. The conductivity in the high-temperature phase at 160 C is 5.5 × 10-3 rs/Omega.gif" BORDER=0 >-1cm-1, and the activation energy for proton transport is 0.40 ± 0.01 eV. These values suggestthat proton transport is facilitated by rapid PO3H group reorientations in the cubic phaseof CsH(PO3H), as is known to occur in the high-temperature, tetragonal phase of CsHSO4.