Relaxor behavior of K0.5La0.5Bi2Nb2O9 ceramics

C. Karthik (1) , N. Ravishankar (1) , K. B. R. Varma (1) , Mario Maglione (2) , Régnault von Der Mühll (2) , Jean Etourneau (2)

1 IISc Bangalore - Indian Institute of Science [Bangalore]
2 ICMCB - Institut de Chimie de la Matière Condensée de Bordeaux

K0.5La0.5Bi2Nb2O9, a relaxor, was synthesized and the structural studies confirmed it to be an n=2 member of the Aurivillius oxides. The (1/2){h00} and (1/2){hk0} types of superlattice reflections in the electron diffraction patterns reflected the presence of ordered polar regions. A broad dielectric peak with frequency dependent dielectric maximum temperature was observed. The dielectric relaxation obeyed the Vogel-Fulcher relation wherein Ea=0.04 eV, Tf=428 K,and omegao=1010 Hz. The diffuseness parameter gamma=2.003 established the relaxor nature and it was attributed to the A-site cationic disorder. The piezoelectric d31 coefficient was 0.5 pC/N at 300 K and 2 pC/N at 480 K.

Mots clés: Niobates; titanates; tantalates; PZT ceramics...; Dielectric loss and relaxation; Ferroelectricity and antiferroelectricity; Piezoelectricity and electromechanical effects; Permittivity (dielectric function); PZT ceramics

Domaines: Matériaux

C. Karthik, N. Ravishankar, K. B. R. Varma, Mario Maglione, Régnault von Der Mühll, et al.. Relaxor behavior of K0.5La0.5Bi2Nb2O9 ceramics. Applied Physics Letters, 2006, 89 (4), 042905 (3 p.). ⟨10.1063/1.2234848⟩. ⟨hal-00111134⟩