AVS 58th Annual International Symposium and Exhibition
    Thin Film Division Monday Sessions
       Session TF-MoM

Paper TF-MoM10
Surface Characterization of Zr/Ti/Nb Tri-layered Films Deposited by Magnetron Sputtering on Si(111) and Stainless Steel Substrates

Monday, October 31, 2011, 11:20 am, Room 107

Session: Thin Films: Growth and Characterization I
Presenter: Pedro Nascente, Federal University of Sao Carlos, Brazil
Authors: D.A. Tallarico, Federal University of Sao Carlos, Brazil
A.L. Gobbi, Brazilian Synchrotron Light Laboratory, Brazil
P.I. Paulin-Filho, Federal University of Sao Carlos, Brazil
A. Galtayries, Ecole Nationale Superieure de Chimie de Paris, France
P.A.P. Nascente, Federal University of Sao Carlos, Brazil
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Titanium is a metal commonly used in medical implants, due to its interesting properties, such as high mechanical strength, good corrosion resistance in extreme conditions, and excellent thermal stability. Ti-6Al-4V is one of the main biomaterial alloys employed as implants, but the release of Al and V ions is associated to health problems and adverse tissue reactions. A new class of Ti alloys employs Zr for solid-solution hardening and Nb as β phase stabilizer. Metals such as Ti, Nb, and Zr, known as valve metals, usually have their surfaces covered by a thin oxide film spontaneously formed in air. This oxide film constitutes a barrier between the metal and the medium. The Ti-Nb-Zr alloys have mechanical and corrosion resistance characteristics which make them suitable for use as implants. Tri-layered films of Ti-Nb-Zr were deposited on both Si(111) and stainless steel substrates using a DC magnetron sputtering equipment, under an argon atmosphere. The films were deposited in the following manner: a 100 nm thick layer of Nb was deposited on a Si(111) substrate, then a 200 nm layer of Ti was deposited on top of Nb/Si, and lastly a 50 nm layer of Zr was deposited on top of Ti/Nb/Si. A similar Zr/Ti/Nb film was also grown on stainless steel substrate. The structure, morphology, and chemical composition of the films were analyzed by means of X-ray diffraction (XRD), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and time-of-flight secondary ion mass spectrometry (ToF-SIMS). The XPS results for the Zr/Ti/Nb layers deposited on Si(111) presented a predominance of ZrO2 on the surface, and Nb2O5 and a small quantity of TiO2. For the layers deposited on stainless steel, only ZrO2 and a small amount of niobium oxide were detected. The ToF-SIMS results indicated the formation a three-layered film on Si(111), with each metal in a distinct layer and a well-defined interface between the layers, while the deposition on the stainless steel substrate caused slight intermixing at the Nb/Ti and Ti/Zr interfaces. AFM images showed that the Zr/Ti/Nb tri-layer films presented nanostructured grains and low roughness, with the film deposited on stainless steel having the roughest surface.