ФТТ, 2004, том 46, выпуск 9

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Fluorine mobility in the aluminum doped CeF3 crystal:
NMR and conductivity studies

C.Tien *, E.V.Charnaya *,**, A.B.Sherman ***

* Department of Physics, National Cheng Kung University,
Tainan 70101 Taiwan
** Institute of Physics, St. Petersburg State University,
St. Petersburg 198904 Russia
*** A.F. Ioffe Physico-Technical Institute, Russian Academy of Sciences,
St. Petersburg, 194021 Russia
E-mail: charnaya@mail.ru

(Received 11 February 2004)

Electrical conductivity and NMR measurements were carried out for the aluminum doped CeF3 crystal to study influence of substitutional impurities on the superionic fluorine mobility. Activation enthalpy was found to remain constant from low temperatures to about 325 K while it increased compared to that of the pure CeF3 crystal. Above about 325 K a trand towards gradual conductivity saturation was observed, this change was ascribed to a superionic phase transition, which was not accompanied with structural transformations. NMR also revealed some alterations in local fluorine dynamics compared to that reported for the pure CeF3 crystal. According to NMR measurements, the superionic phase transition near 325 K results in acceleration of the exchange between rigid or slow fluorine in the F1, F2 and F3 sublattices while highly mobile F1 fluorine ions move independently at least until 400 K.

The present work was supported by the National Science Council of Taiwan under Grant 92-2811-M-006-014.

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