Relations between ionic order or disorder and classical or, relaxer ferroelectric behaviour in two lead-free TKWB-type ceramics

Authors
Ravez, J El Alaoui-Belghiti, H Elaatmani, M Simon, A
Citation
J. Ravez et al., Relations between ionic order or disorder and classical or, relaxer ferroelectric behaviour in two lead-free TKWB-type ceramics, MATER LETT, 47(3), 2001, pp. 159-164
Citations number
12
Categorie Soggetti
Apllied Physucs/Condensed Matter/Materiales Science","Material Science & Engineering
Journal title
MATERIALS LETTERS
ISSN journal
0167577X → ACNP
Volume
47
Issue
3
Year of publication
2001
Pages
159 - 164
Database
ISI
SICI code
0167-577X(200101)47:3<159:RBIOOD>2.0.ZU;2-O
Abstract
Two ceramics of Ba2NaNb5O15 and BaNa2Nb5O14F compositions, which have a tet ragonal tungsten bronze (TKWB)-type structure, are synthesized and characte rised by dielectric measurements. Their ferroelectric properties an correla ted with the ionic order or disorder in the crystalline network. The oxide is a classical ferroelectric, whereas the oxyfluoride shows a relaxer ferro electric behaviour in agreement with cationic disorder of Ba2+ and Na+ in t he same 15 C.N. crystallographic site. The relaxer characteristics are comp ared to those of well-known perovskites. BaNa2Nb5O14F is the first lead-fre e oxyfluoride relaxer of TKWB type. (C) 2001 Elsevier Science B.V. All righ ts reserved.