Recent Developments in K 1−x Li x Ta 1−y Nb y O 3 Investigations

KTaO 3 with small amount ( x < 0.01) of Li and simultaneously diluted by Nb (K 1 m x Li x Ta y Nb 1 m y O 3 , KLTN) reveals original dipole ordering structural effects. Small Nb co-dopings ( y < 0.007) enhance the trend of the Li + off-centers related subsystem towards cooperative ordering and order-disorder phase transitions. At 0.01 < y < 0.05 the intrigue features of displacive and order-disorder transitions reveal. The most interesting features are the appearance of soft-mode driven ferroelectric transitions accompanied by a Li + off-centers system freezing followed by a reentrant dipole glass-like phase formation, and the emergence of a narrow transition with giant magnitude of l '(T). Evidences of reentrant dipole glass formation were observed in KTa 0.981 Nb 0.019 O 3 too. A possible model developed is based on the Li-Nb polar clusters, local configuration instabilities and superparaelectricity conceptions.

Keywords:

• Incipient Ferroelectrics
• Impurity Effects
• Phase Transitions