J. Phys. I France
Volume 7, Numéro 3, March 1997
Page(s) 543 - 552
DOI: 10.1051/jp1:1997106
J. Phys. I France 7 (1997) 543-552

Non-Linearity Extremum in Niobium Doped Potassium Tantalate

O. Bidault and M. Maglione

Laboratoire de Physique, Université de Bourgogne, UPRESA CNRS 5027, BP 138, 21004 Dijon, France

(Received 29 July 1996, revised 16 October 1996, accepted le 20 November 1996)

We report non-linear dielectric measurements in the KTaO 3:Nb system ( $x_{\rm Nb}\leq 0.05$). The non-linear susceptibility diverges at low temperatures and reaches maximum values in the intermediate range ( $0.0075\leq x_{\rm Nb}\leq 0.02$). To account for this extremum non linearity, we propose a model of temperature dependent clusters which fits with a number of experimental reports. We also suggest that this model may be applied to the related compounds SrTiO 3:Ca and KTaO 3:Ca.

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