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High-temperature phase behavior in the Rb_3H(SO_4)_2–RbHSO_4 pseudo-binary system and the new compound Rb_5H_3(SO_4)_4

Panithipongwut, Chatr and Haile, Sossina M. (2012) High-temperature phase behavior in the Rb_3H(SO_4)_2–RbHSO_4 pseudo-binary system and the new compound Rb_5H_3(SO_4)_4. Solid State Ionics, 213 . pp. 53-57. ISSN 0167-2738. doi:10.1016/j.ssi.2011.10.016.

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The high temperature behavior of the pseudo-binary system Rb_3H(SO_4)_2–RbHSO_4 has been investigated through a combination of thermal analysis, high-temperature X-ray powder diffraction and high-temperature electrical impedance measurements. The studies reveal the existence of a new high-conductivity phase, Rb_5H_3(SO_4)_4, that becomes stable at a temperature between 25 and 140 °C and is isostructural to a recently reported trigonal phase of Cs_5H_3(SO_4)_4 [M. Sakashita, et al., Solid State Ionics (2007) 178 1262–1267]. Refinement of the Rb structure in space group P3–m at 160 °C yields a = 5.9298(2) Å, c = 14.4736(6) Å, V = 440.74(3) Å^3, with Z = 1 and ρ = 3.0691(2) Mg/m^3. At 185 °C the compound undergoes an apparently polymorphic transformation with a heat of transition of 14.9 kJ/mol and a slight additional increase in conductivity. No further anomalies are observed up to the highest measurement temperature of 220 °C. Compositions rich in Rb_3H(SO_4)_2 relative to Rb_5H_3(SO_4)_4 show, in addition to the polymorphic transformation of the latter, the disproportionation reaction of the former into Rb_2SO_4 and Rb_5H_3(SO_4)_4 at 205 °C. Compositions rich in RbHSO_4 display an additional conductivity anomaly at 170 °C, which is tentatively assigned to a polymorphic transformation in RbHSO_4.

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Haile, Sossina M.0000-0002-5293-6252
Additional Information:© 2011 Elsevier B.V. Received 22 April 2011. Revised 11 October 2011. Accepted 12 October 2011. Available online 20 November 2011. For useful discussions and assistance with data acquisition and analysis, the authors thank Mary Louie and Ayako Ikeda. Financial support has been provided by the U.S. National Science Foundation (DMR-0906543) and the Army Research Office (W911NF-07-1-0410). Additional funding has been provided by the Ministry of Science and Technology of Thailand through the Royal Thai Scholarship.
Funding AgencyGrant Number
Army Research Office (ARO)W911NF-07-1-0410
Ministry of Science and Technology of ThailandUNSPECIFIED
Subject Keywords:Trirubidium hydrogen disulfate; Rubidium hydrogen sulfate; Pentarubidium trihydrogen tetrasulfate; Phase diagram; A.C. impedance spectroscopy; X-ray diffraction; Rb3H(SO4)2; RbHSO4; Rb5H3(SO4)4; Solid acid
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Official Citation:Chatr Panithipongwut, Sossina M. Haile, High-temperature phase behavior in the Rb3H(SO4)2–RbHSO4 pseudo-binary system and the new compound Rb5H3(SO4)4, Solid State Ionics, Volume 213, 16 April 2012, Pages 53-57, ISSN 0167-2738, 10.1016/j.ssi.2011.10.016. (
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:31691
Deposited By: Ruth Sustaita
Deposited On:30 May 2012 15:22
Last Modified:09 Nov 2021 19:58

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