CICECO » Impedance spectroscopy and piezoresponse force microscopy analysis of lead-free (1-x) K0.5Na0.5NbO3

authors	Rai, R; Coondoo, I; Rani, R; Bdikin, I; Sharma, S; Kholkin, AL
nationality	International
journal	CURRENT APPLIED PHYSICS
author keywords	Ceramics; Impedance spectroscopy; X-ray diffraction; Dielectric properties; Phase transactions
keywords	FREE PIEZOELECTRIC CERAMICS; MODIFIED PBTIO3 NANOCERAMICS; MODULUS SPECTROSCOPY; TEMPERATURE STABILITY
abstract	(1 - x) K0.5Na0.5NbO3 - xLiNbO(3) (where x = 0.0, 5.0, 5.5, 6.0, and 6.5 wt.%) (KNLN) perovskite structured ferroelectric ceramics were prepared by the solid-state reaction method. X-ray diffraction patterns indicate that single phase was formed for pure KNN while a small amount of second phase (K6Li4Nb10O30, similar to 3%) was present in LN doped KNN ceramics. Phase analysis indicated the change in the crystal structure from orthorhombic to tetragonal with increase in LN content. The electrical behavior of the ceramics was studied by impedance spectroscopy technique in the high temperature range. Impedance analysis was performed using an equivalent circuit model. The impedance response in pure KNN and KNLN ceramics could be deconvoluted into two contributions, associated with the bulk (grains) and the grain boundaries. Activation energies for conductivity were found to be strongly frequency dependent. The activation energy obtained from dielectric relaxation data was attributed to oxygen vacancies. From PFM we found that the composition with 6.5 wt.% LN displays stronger piezocontrast as compared to pure KNN implying an evidence of a pronounced piezoelectric coefficient. (c) 2012 Elsevier B.V. All rights reserved.
publisher	ELSEVIER SCIENCE BV
issn	1567-1739
year published	2013
volume	13
issue	2
beginning page	430
ending page	440
digital object identifier (doi)	10.1016/j.cap.2012.09.009
web of science category	Materials Science, Multidisciplinary; Physics, Applied
subject category	Materials Science; Physics
unique article identifier	WOS:000310817400023