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.
keywords
FREE PIEZOELECTRIC CERAMICS; MODIFIED PBTIO3 NANOCERAMICS; MODULUS SPECTROSCOPY; TEMPERATURE STABILITY
subject category
Materials Science; Physics
authors
Rai, R; Coondoo, I; Rani, R; Bdikin, I; Sharma, S; Kholkin, AL
our authors
Andrei Kholkin
Retired Researcher
Indrani Coondoo
Junior Researcher
Radheshyam Rai
Post-doc FellowshipProjects
NOLEAD: Novel lead-free ferroelectric films by PLD for optoelectronics (PTDC/FIS/108025/2008)
acknowledgements
The authors are grateful to the Foundation for Science and Technology of Portugal (FCT) for financial support within the projects PTDC/CTM-CER/115085/2009 and PTDC/FIS/108025/2008. The work is partly supported by the EU network Enermat.aa. Seema Sharma wish to acknowledge Department of Science and Technology, Govt of India (SR/S2/CMP-39/2006), India for the financial support under a research project scheme.