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Microstructure of sputter-deposited noble metal-incorporated oxide thin films patterned by means of laser interference Rodolphe Catrin1,*, Thomas Gries1,a, David Horwat2, Sylvie Migot2 and Frank Muecklich1 1

Functional Materials, Saarland University, Campus D3.3, D-66123 Saarbruecken, Germany.

2

Institut Jean Lamour, Département CP2S, UMR 7198, École des Mines de Nancy, Parc de Saurupt, F-54042 Nancy, France. ABSTRACT Laser interference patterning-induced microstructural modifications have been investigated in two noble metal-incorporated oxide thin film systems: Pd0.25Pt0.75Ox and goldincorporated yttria-stabilized zirconia - Au-YSZ. Transmission electron microscopy was used to investigate the influence of the laser treatment on the microstructure of the samples. In the case of Pd0.25Pt0.75Ox, the formation of a nanocomposite arrangement resulted from the precipitation of metal nanograins in the oxide matrix triggered by laser irradiation. In Au-YSZ, the starting microstructure consisted of gold nanograins embedded in a YSZ matrix. A noticeable growth and coalescence of gold nanograins occurred near the surface in the region of maximum interference. Simultaneously, a foamy morphology, mostly consisting of gold crystals, was formed at the film surface. In contrast to thermal annealing, the laser treatment proposed here is a fast procedure to partially relocate gold at the film surface and provide a local solid lubrication. INTRODUCTION Innovation in materials science relies on the possibility to control the morphology, microstructure and chemistry of materials. Thereby, specific properties can be obtained. Noble metals are fascinating for various aspects, among which is their poor reactivity towards oxygen. The association of noble metals with other metallic elements can produce original microstructures and morphologies, more particularly upon thermal annealing and in the presence of oxygen [1,2]. We showed recently that the electrical conductivity of noble metal-based oxides and nitrides could be tailored by laser interference patterning [3]. Within this method, described in detail in [4], the interference of single laser pulses is used to tailor both morphology and microstructure of thin films [5]. Due to a high local thermal gradient produced in a very short time, metallurgical effects like lateral grain growth [5,6], chemical decomposition [3] or intermetallic phase precipitation [7] are promoted. The present study is dedicated to the effect of laser interference patterning on the microstructure of sputter-deposited Pd0.25Pt0.75Ox and goldincorporated yttria-stabilized zirconia (Au-YSZ) thin films. These two chemical systems are of interest for their potential applications in the field of catalysis [2,8,9]. Moreover Au-YSZ nanocomposites exhibit improvements in tribological properties due to microstructure adaptive changes influencing the friction coefficient [10]. From the viewpoint of thermodynamics the two systems are very different since PdO and Pt oxides are stable at room temperature, while gold *

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