Structural analyses of Nd-doped CeO thin films deposited by pulsed laser deposition

CeO(2) thin films doped with neodymium oxides for application to gas sensors have been elaborated by the pulsed laser deposition technique. The films were deposited on orientated Si (100) substrates with variable deposition times (t = 90, 180 and 360 s) and molar fractions of Nd(2)O(3) (0, 6.5, 15, 21.5 and 27 at.%). The resulting Nd-CeO(2) thin films were characterized by means of X-ray diffraction analysis, scanning electron microscopy and transmission electron microscopy equipped with EDS (Energy Dispersive Spectrometer) microanalysis. From X-ray diffraction analyses, it is clearly established that the texture is modified by Nd additions. The preferred (111) orientations of the CeO(2) crystals change into the (200) orientation. The morphology of the CeO(2) grains changes from triangles, for pure CeO(2) thin films, to spherical grains for Nd-doped films. In addition, cell parameter analyses from X-ray diffraction data show that a partial chemical substitution of Ce by Nd should occur in the face-centred cubic lattice of ceria: this should give rise to Ce(1-x)Nd(x)O(2-z) phases with oxygen non-stoichiometry.