Descrição
Metallic (Me) oxynitrides (MeNxOy) are an attractive class of materials due to a unique
set of versatile properties in different technological domains such as protective
applications (wear, diffusion and corrosion-resistance), decorative coatings, gas barriers,
microelectronics, optoelectronics, solar cells, etc. Among the group of oxynitrides,
aluminium oxynitride (AlNxOy) presents some interesting characteristics to be used in
different technological fields, since it may combine the behaviour of metallic
aluminium, and those of the base binary systems: aluminium nitride, known for its
semiconducting and piezoelectric properties and aluminium oxide, for its protective and
insulating performances. In this work, thin films of AlNxOy were prepared by reactive
DC magnetron sputtering, using a pure Al target and an Ar/(N2,O2) gas mixture. The
overall set of results suggests the formation of a nanocomposite-like material for some
stoichiometries, with Al nanoparticles embedded in an AlNxOy matrix, forming a
percolating network. This particular microstructure induced a wide variation in
electrical properties [1], such as a gradual transition from positive to negative
temperature coefficients of resistance (TCR) as the (N+O)/Al atomic ratio increases; as
well as distinct optical responses [2], such as an unusual low and constant optical
reflectance nearly independent of the wavelength (250 – 2500 nm), which opens the
possibility of using the AlNxOy films in different applications, either in electrical or
optical-based devices. The films were also tested in terms of electrochemical and
corrosion behaviour, focusing this study on the influence of the immersion in NaCl
solutions, which simulate the effect of sweat, on the electrochemical and optical
performance of the coatings. Results showed that the films electrochemical and optical
responses are very stable, even when immersed for several weeks.
; Martin, N. 
