A Caltech Library Service

Engineering the Next Generation of Solid State Proton Conductors: Synthesis and Properties of Ba_(3−x)K_(x)H_(x)(PO_4)_2

Chisholm, Calum R. I. and Toberer, Eric S. and Louie, Mary W. and Haile, Sossina M. (2010) Engineering the Next Generation of Solid State Proton Conductors: Synthesis and Properties of Ba_(3−x)K_(x)H_(x)(PO_4)_2. Chemistry of Materials, 22 (3). pp. 1186-1194. ISSN 0897-4756.

Full text is not posted in this repository. Consult Related URLs below.

Use this Persistent URL to link to this item:


A new series of compounds with general chemical formula Ba_(3−x)K_(x)H_(x)(PO_4)_2 has been successfully prepared. This particular stoichiometry was targeted as a candidate solid-state proton conductor because of its anticipated structural similarity to known M_(3)H(XO_4)_2 superprotonic conductors (M = Cs, Rb, NH4, K; X = Se, S) and to the known trigonal compound Ba_(3)(PO_4)_2. The materials were synthesized from aqueous solution using barium acetate, dipotassium hydrogen phosphate, and potassium hydroxide as starting materials. Through variations in the initial solution stoichiometry or the synthesis temperature, the final stoichiometry could be controlled from x ~ 0.5 to ~1. X-ray powder diffraction, energy dispersive spectroscopy chemical analysis, ^(1)H magic angle spinning (MAS) nuclear magnetic spectroscopy, and thermogravimetric analysis were all employed to establish potassium and proton incorporation. The diffraction data confirmed crystallization of a trigonal phase, and chemical analysis showed the (Ba+K):P ratio to be 3:2, consistent with the target stoichiometry. The conductivity of the Ba_(3−x)K_(x)H_(x)(PO_4)_2 materials, as measured by A.C. impedance spectroscopy, is about 3 orders of magnitude greater than the end-member Ba_(3)(PO_4)_2 material with only a slight dependence on x, however, it is substantially lower than that of typical superprotonic conductors and of the M_(3)H(XO_4)_2 materials in particular. The close proximity of Ba to the hydrogen bond site is proposed to explain this behavior. At 250 °C, the conductivity is 2.4 × 10^(−5) S/cm for the composition x = 0.80, which, when combined with the water insolubility and the relatively high thermal stability, may render Ba_(3−x)K_(x)H_(x)(PO_4)_2 an attractive alternative in selected electrochemical applications to known superprotonic conductors.

Item Type:Article
Related URLs:
URLURL TypeDescription
Haile, Sossina M.0000-0002-5293-6252
Additional Information:© 2010 American Chemical Society. Received August 28, 2009. Revised Manuscript Received November 6, 2009. Publication Date (Web): January 7, 2010. The authors are pleased to acknowledge the financial support of the National Science Foundation through award #0906543. Dr. Sonjon Hwang kindly assisted with the acquisition of NMR data.
Funding AgencyGrant Number
Issue or Number:3
Record Number:CaltechAUTHORS:20100304-142450954
Persistent URL:
Official Citation:Engineering the Next Generation of Solid State Proton Conductors: Synthesis and Properties of Ba3−xKxHx(PO4)2 Calum R.I. Chisholm, Eric S. Toberer, Mary W. Louie, Sossina M. Haile Chemistry of Materials 2010 22 (3), 1186-1194
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:17669
Deposited By: Jason Perez
Deposited On:08 Mar 2010 21:15
Last Modified:03 Oct 2019 01:31

Repository Staff Only: item control page