ISSN:
1434-6036
Keywords:
PACS. 71.20.-b Electron density of states and band structure of crystalline solids - 77.80.-e Ferroelectricity and antiferroelectricity - 77.84.Dy Niobates, titanates, tantalates, PZT ceramics, etc.
Source:
Springer Online Journal Archives 1860-2000
Topics:
Physics
Notes:
Abstract: Values of Curie temperature, TC, and microwave relaxation frequency, fr, of ferroelectric niobates and tantalates are found to be closely related to the metal-oxygen network covalency. Correlations previously evidenced in perovskite-type relaxors (PSN, PST) are confirmed here for K(Ta1-xNbx)O3 (KTN) compositions. The investigated physical characteristics, TC and fr, are determined via dielectric measurements performed in a wide frequency range (102-109 Hz) and as a function of temperature (250-800 K). On a theoretical point of view, bond covalencies are evaluated through tight-binding band structure calculations. The complex role of covalency on the metal potential is precised. Two antagonist effects acting on both the short-range interatomic repulsions and the rigidity and stability of the oxygen-metal network are discussed. The validity of this approach is comforted through the example of the oxyfluoride K3Li1.5Ta5O14.5F0.5.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/s100510050553
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