Optical properties of ceriaezirconia epitaxial films grown from chemical solutions O. Peña-Rodríguez a, b, c, * , C.F. Sánchez-Valdés a , M. Garriga a, * , M.I. Alonso a , X. Obradors a , T. Puig a a Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus UAB, Bellaterra, Barcelona 08193, Spain b Centro de Microanálisis de Materiales (CMAM), Universidad Autónoma de Madrid (UAM), Cantoblanco, Madrid 28049, Spain c Instituto de Óptica, Consejo Superior de Investigaciones Científicas (IO-CSIC), C/Serrano 121, Madrid 28006, Spain highlights < Epitaxial ceriaezirconia thin films were grown by chemical solution deposition. < The obtained solid solutions covered the whole concentration range. < Optical constants of the thin film were determined from ellipsometry measurements. < Mixed-oxide’s optical properties smoothly varied between those of the pure oxides. article info Article history: Received 23 March 2012 Received in revised form 19 November 2012 Accepted 25 November 2012 Keywords: Optical properties Thin films Polarimeters and ellipsometers Organometallic compounds abstract Epitaxial thin films of ceriaezirconia solid solutions were grown on yttria-stabilized zirconia (YSZ) substrates by chemical solution deposition. Characterization by X-ray diffraction, atomic force micros- copy and variable angle spectroscopic ellipsometry show that high-quality, epitaxial, high density films, with a thickness in the range of 20e27 nm were obtained. Compositional dependence of the film optical constants (n and k) was determined from ellipsometry measurements. It was found that the optical properties for the mixed-oxide films smoothly vary between the values for the pure oxides and are best described by means of a TauceLorentz (TL) model. Moreover, we found that the parameters of the TL model have a linear dependence on the cerium concentration. The obtained results can serve as a database for the thickness, composition and porosity characterization of Ce x Zr 1x O 2 thin films. Ó 2012 Elsevier B.V. All rights reserved. 1. Introduction Ionic compounds like ceria (CeO 2 ), either pure or doped with different elements, have generated great interest due to their high chemical stability, good dielectric strength, high refractive index, good optical transmittance in the visible and infrared regions, and high efficiency for absorbing ultraviolet radiation. They also exhibit a high stability against mechanical abrasion and chemical erosion due to their strong adhesion to surfaces [1]. Moreover, cerium dioxide films have a wide variety of technological applications in fields like chemo-mechanical polishing [1], electrochemical devices [1e3], catalysis [4,5], oxygen storage [4,6] and sensing [7], fuel [8] and solar [2] cells, microelectronics [9e11] and optical coatings [12e16]. Ceria can also be used as an excellent buffer layer for superconducting coated conductors [17e19] or nanotemplates [20,21]. Epitaxial CeO 2 thin films have been grown on top of many types of substrates by several methods such as sputtering [22,23], pulsed laser deposition [24], chemical solution deposition [25], ion beam assisted magnetron deposition [26] and electron beam evaporation [27]. In particular, within chemical solution deposition, metal- organic decomposition (MOD) has proved to be a very versatile, scalable and low-cost methodology for preparing functional films. In this work epitaxial Ce x Zr 1x O 2 thin films have been successfully deposited on yttria-stabilized zirconia single crystal substrates by MOD, being x and 1  x the mole fractions of cerium and zirconium atoms, respectively. The interest on this Ce x Zr 1x O 2 solid solution stems from the improvements in the epitaxial growth with respect to CeO 2 . This enhancement has been ascribed to a grain boundary reconstruction due to an increase of atomic mobility, which enabled complete eradication of C atoms at the grain boundaries [17,28]. In particular, a w10% of Ce atoms replaced by Zr has been * Corresponding authors. Institut de Ciència de Materials de Barcelona (ICMAB- CSIC), Campus UAB, Bellaterra, Barcelona 08193, Spain. E-mail addresses: ovidio@bytesfall.com (O. Peña-Rodríguez), miquel@icmab.es (M. Garriga). Contents lists available at SciVerse ScienceDirect Materials Chemistry and Physics journal homepage: www.elsevier.com/locate/matchemphys 0254-0584/$ e see front matter Ó 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.matchemphys.2012.11.069 Materials Chemistry and Physics 138 (2013) 462e467