Electrical and structural investigations of perovskite structure reactively sputter deposited coatings

Abstract

Sr(Zr 0.84Y 0.16) 0.91O 3 − δ (SZY) and Ba(Zr 0.84Y 0.16) 0.96O 3 − δ (BZY) protonic conductor coatings were co-sputter deposited from metallic targets in argon–oxygen reactive gas mixtures. The chemical and structural features were investigated by energy dispersive X-ray spectroscopy and X-ray diffraction, and their morphology was assessed by scanning electron microscopy of the surface and of brittle fracture cross sections. The electrical properties of the coating were determined by complex impedance spectroscopy as a function of temperature in air. Relationships are established between the electrical properties and the morphology of the coatings. The SZY as deposited coatings is amorphous and crystallises under the convenient perovskite structure after annealing treatment at 873 K under air. The BZY as deposited coatings is crystallised at 523 K in situ under perovskite structure and a further annealing treatment increases the grain size. Conductivities and activation energies of crystallised coatings were 3.1 · 10 − 5 S cm − 1 /2 · 10 − 5 S cm − 1 and 0.65 eV/0.71 eV after stabilization at 773 K for strontium and barium zirconate, respectively.