Electrical Conductivity of Cubic/Tetragonal Phase Stabilized Nanocrystalline La2O3 doped ZrO2
|Paramasivam Thangadurai 1, Sinnanadar Ramasamy , Arumugam Chandra Bose|
1. University of Madras, Department of Nuclear Physics, Guindy Campus, Chennai 600025, India
La2O3 doped nanocrystalline zirconia (ZrO2) was prepared by chemical co-precipitation method for the 3, 5, 8, 10, 15, 20 and 30 mol% concentrations of La2O3 . X-ray diffraction (XRD) showed that the as-synthesized samples contain only monoclinic phase. Annealing at higher temperatures lead to tetragonal/cubic structural phase stabilization. Sintering the samples at temperature 1173 K stabilized the tetragonal and cubic phases. Grain sizes were found to lie between 10 and 13 nm. Electrical conductivity studies were performed on the cubic/tetragonal phase stabilized La2O3 -ZrO2 by complex impedance spectroscopy. The conductivity increases up to the dopant concentration 10 mol% and then decreases with further increase in La2O3 concentration. Initial increase in conductivity is correlated to the stabilization of the cubic phase and the subsequent decrease in the conductivity with the dopant content is interpreted on the basis of the oxygen-ion movement model. Electrical conductivity has contributions from grain and grain boundary regions. But the grain boundary conductivity is slightly higher than the corresponding grain conductivity. Higher grain boundary conductivity shows higher diffusion coefficient for the atoms on the surface of the ZrO2 grains. The possible mechanism of the oxygen ion conduction in the La2O3 stabilized zirconia (LSZ) is reported.
Presentation: poster at E-MRS Fall Meeting 2005, Laser Ceramic Symposium, by Thangadurai Paramasivam
See On-line Journal of E-MRS Fall Meeting 2005
Submitted: 2005-05-29 21:07 Revised: 2009-06-07 00:44