Naslov
ESR study of Electron-Nuclear Dipolar Relaxation for AsO_4^4- Spin Probe in the Paraelectric Phase of KH_2AsO_4

Autori
Rakvin, Boris ; Merunka, Dalibor

Izvornik
Journal of magnetic resonance (San Diego, Calif.) (1090-7807) 126 (1997), 1; 87-94

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
ESR; ferroelektrics; spin probe; electron-nuclear dipolar relaxation
(ESR; ferroelectrics; spin probe; electron-nuclear dipolar relaxation)

Sažetak
Saturation behavior of allowed and forbidden ESR transition of AsO44-paramagnetic probe in KH2AsO4 was studied in the wide temperature interval around the paraelectric - ferroelectric phase transition, T-c. The ratios between forbidden and allowed line intensities were employed to deduce information on the electron-nuclear dipolar (END) relaxation mechanism. It was shown that a proton END relaxation mechanism exhibits an extremal temperature behavior in the paraelectric phase around 230 K. The extremal temperature behavior was described by employing a model of proton hopping along the O-H ... O bonds around the paramagnetic centers, and the correlation time of this hopping was estimated in the wide temperature range in the paraelectric phase (150-330 K) The temperature dependence of effective proton distance from the neighbor oxygens was obtained, and it was discussed in terms of a localization of the spin density on these oxygens caused by charge inbalance in the As-O bonds in the ferroelectric phase.

Izvorni jezik
Engleski

Znanstvena područja
Kemija

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