Materials Science and Engineering B104 (2003) 163–168 Structure and phase component of ZrO 2 thin films studied by Raman spectroscopy and X-ray diffraction Le Duc Huy a,∗ , P. Laffez a , Ph. Daniel a , A. Jouanneaux a , Nguyen The Khoi b , D. Siméone c a Laboratoire de Physique de l’Etat Condensé, UPRES A CNRS no. 6087, F-72085 Le Mans cedex, France b Faculty of Physics, Hanoi University of Education, 136 Avenue Xuan Thuy-Cau Giay, Hanoi, Viet Nam c SEMI, Lab. d’Etudes Matériaux Absorbents, CEA, CE Saclay, F-91191 Gif sur Yvette cedex, France Abstract Zirconia (ZrO 2 ) thin films were deposited by RF magnetron sputtering on zircaloy-4 (Zy-4) substrates directly from the ZrO 2 target. These thin films, deposited at different substrate temperatures from 40 to 800 ◦ C and within different times from 10 to 240 min, were investigated by Raman spectroscopy and by X-ray diffraction (XRD). A rather good agreement between the results given by the two techniques was obtained. By comparison between the Raman studies on zirconia thin films and on bulk zirconia, it is possible to conclude the following: (i) films are polycrystalline; (ii) ZrO 2 is not completely dissociated during the deposition process; (iii) the structure and phase composition of the films depend on the substrate temperature and on the deposition time, thickness and, therefore, vary as a function of the distance from the film surface. © 2003 Elsevier B.V. All rights reserved. Keywords: Zirconia thin film; Phase component; RF sputtering; Raman spectroscopy; X-ray diffraction 1. Introduction Zirconium alloys such as zircaloy-4 (Zy-4) are used for fuel-elements cladding and in-core structural element in pressurised water reactor (PWR). One of the major prob- lems encountered in these elements of PWR is the oxidation under water effect. This oxidation process creates a zirconia (ZrO 2 ) thin layer. This oxidation is a drastic factor limiting the time-life of the fuel-elements cladding and that restrains the productiveness of the PWR. Previous structural inves- tigations [1] have shown that under neutron irradiation the monoclinic stable room temperature phase of zirconia layer can be partially transformed into tetragonal zirconia. The appearance of the ZrO 2 layer in tetragonal form seems to be connected to a quicker degradation of the cladding and conversely the development of a stable monoclinic zirconia is considered as a valid way to limit the destructive cor- rosion of the zircaloy. Thus it appears very important to understand physical mechanism induced by irradiation in the monoclinic-tetragonal transition. ∗ Corresponding author. E-mail address: duc huy.le@univ-lemans.fr (L. Duc Huy). The aim of this work is to study the mechanism of ZrO 2 thin films growth in order to bring valuable information to transfer it in the real system PWR. ZrO 2 thin films can be obtained by different methods, such as thermal evaporation [2], reactive dc sputtering [3], RF reactive magnetron sputtering [4–8], sol–gel processing [9], laser and electron ablation [10], chemical vapour de- position [11], and electrochemical deposition [12,13]. It is well known that the crystalline structure and the properties of the films depend strongly on the deposition method and deposition conditions. In this work, the RF magnetron sput- tering deposition method was used to produce zirconia thin films on Zy-4 substrate, which is the constitutive material of cladding in PWR. We have grown ZrO 2 thin films of different thickness and at different temperature on Zy-4 and have characterised their structure and phase component by X-ray diffraction (XRD) and Raman scattering. 2. Experimental procedure The zirconia thin films were deposited by RF magnetron sputtering directly from the zirconia target. The MP300 equipment manufactured by PLASSYS was used. The target 0921-5107/$ – see front matter © 2003 Elsevier B.V. All rights reserved. doi:10.1016/S0921-5107(03)00190-9