76. A-site acceptor doped LaNbO4 thin film formation and structural investigation

Kristina Bockute1, Darius Virbukas2, Giedrius Laukaitis3

Physics Department, Kaunas University of Technology, Studentu 50, LT-51368 Kaunas, Lithuania

3Corresponding author

E-mail: 1kristina.bockute@ktu.lt, 2darius.virbukas@ktu.lt, 3giedrius.laukaitis@ktu.lt

(Received 7 October 2015; received in revised form 10 December 2015; accepted 21 December 2015)

Abstract. In this paper, doped La1-xAxNbO4 (A = Ca, Mg) thin films were formed using electron beam vapor deposition. The influence of the doping concentration of A site dopants (A = Ca, Mg) on the thin ceramics surface microstructure, morphology and electrical properties, including the charge carrier mobility and diffusion coefficient, was studied. It was found that the formed thin films are dense (>96 %) and have homogenous nanocrystalline structure composed of the tetragonal LaNbO4 phase. The total conductivity of the formed thin films is in 10-3 S/cm range for Ca-doped LaNbO4 and 10-4 S/cm range for Mg-doped LaNbO4 at 800 °C under wet H2 reducing atmosphere. The nature of protonic conduction was confirmed by the isotopic effect. The calculated  is 57 kJ/mol at 650 °C for the La0.995Ca0.005NbO4 film, which total conductivity was highest in the present study (9.52∙10-3 S/cm at 800 °C under wet H2 reducing atmosphere).  increases steadily with increasing the dopants’ concentration from 57 kJ/mol to 84 kJ/mol. The charge mobility decreases from 2.32×10-5 cm2/V∙s to
6.25×10-7 cm2/V∙s as the dopants’ concentration increases at 650 °C.

Keywords: electron beam evaporation, nanocrystalline, proton conducting fuel cells (PCFC), doped lanthanum niobium oxide, LaNbO4.

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Cite this article

Bockute Kristina, Virbukas Darius, Laukaitis Giedrius A‑site acceptor doped LaNbO4 thin film formation and structural investigation. Journal of Measurements in Engineering, Vol. 3, Issue 4, 2015, p. 105‑113.

 

Journal of Measurements in Engineering. December 2015, Volume 3, Issue 4

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