Naslov
Phase transition and conductivity mechanism in the ionic conductor Cu2HgI4

Autori
Pelc, Damjan ; Marković, Igor ; Požek Miroslav

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
Magnetic Resonance Conference (Euromar 2011) : abstracts / Prisner, Thomas - Göttingen : Cuvillier Verlag, 2011, 304-304

ISBN
978-3-86955-845-5

Skup
Magnetic Resonance Conference

Mjesto i datum
Frankfurt na Majni, Njemačka, 21.08.2011. - 25.08.2011

Vrsta sudjelovanja
Poster

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
ionic conductors; nuclear magnetic resonance; nonlinear conductivity

Sažetak
The first multinuclear, frequency-dependent NMR investigation of the ionic conductor Cu2HgI4 is presented, giving new insights into the ion dynamics in this compound. At 344 K it undergoes a transition from insulator to ionic conductor, which we were able to follow in detail. Pretransitional fluctuations are observed in copper NMR, with a mean-field theory providing an adequate description. Spin-lattice relaxation measurements provide information about defect motion below the transition, with discernible effects from both copper and mercury. At the transition temperature the copper sublattice is disordered, line broadening is observed and the relaxation time drops abruptly for a factor of 50. In contradistinction, the mercury line shows a substantial narrowing in the conductive phase, indicating that Hg2+ ions are the main contributors to conduction. This is in disagreement with the consensus view that conduction is dominated by copper ions [1], so we performed constant field gradient diffusion measurements to confirm mercury motion. In the extreme narrowing regime (above ~380 K) the signal decay exactly follows the prediction for diffusing spins [2], providing unambiguous evidence of mercury diffusion. We discuss the role of dynamic correlations in enabling the motion of the large and heavy mercury ions. This work is enabled by the European Commission through FP7 project #229390 SOLeNeMaR. 1. Hull S., Keen D. A., J. Phys.: Cond. Mat. 12, 3751-3765 (2000) 2. Hahn E. L., Phys. Rev. 80, 580 (1950)

Izvorni jezik
Engleski

Znanstvena područja
Fizika

POVEZANOST RADA