EPR Study of VO2+ Center in Fast Proton Conductor K3H(SO4)2

A. Ostrowski, S. Waplak and W. Bednarski Institute of Molecular Physics, Polish Academy of Sciences, Smoluchowskiego 17, 60-179 Poznań, Poland

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Received: 24 04 2005;

The pretransitional phenomena of superprotonic phase transition (Tsp=471 K) were studied in detail by X-band continuous wave EPR spectra of K3H(SO4)2 crystal doped with VO2+ ions. Three kinds of VO2+ complexes (magnetically equivalent but structurally non-equivalent) denoted as VO2+(I), VO2+(II), and VO2+(III) were found. ``Smearing out'' of the superhyperfine structure was observed as a result of interbond proton motion. VO2+ impurity replaces K^+ ion and experiences the same average crystal field gradient at Tsp=471 K for I- and II-type complexes. The increase in interbond proton frequency hopping above 360 K is a reason of significant line broadening.

DOI: 10.12693/APhysPolA.108.127 PACS numbers:61.50.-f, 76.30.-v