AVS 60th International Symposium and Exhibition
    Thin Film Thursday Sessions
       Session TF-ThP

Paper TF-ThP11
Electrochemical Corrosion of Thin Ferromagnetic Fe-N Films in Neutral Solution

Thursday, October 31, 2013, 6:00 pm, Room Hall B

Session: Thin Films Poster Session
Presenter: S.A. Maklakov, Institute for Theoretical and Applied Electromagnetics, Russian Federation
Authors: S.S. Maklakov, Institute for Theoretical and Applied Electromagnetics, Russian Federation
S.A. Maklakov, Institute for Theoretical and Applied Electromagnetics, Russian Federation
A.S. Naboko, Institute for Theoretical and Applied Electromagnetics, Russian Federation
I.A. Ryzhikov, Institute for Theoretical and Applied Electromagnetics, Russian Federation
Correspondent: Click to Email
Energy and information transfer is an actual task in biosensors. Thin ferromagnetic films are widely used as antennas and magnetic field sensors[1]. The study of corrosion behavior in neutral solutions serves fundamental interest and practical applications.

Corrosion behavior is reported for Fe-N films (h = 150 and 300 nm) deposited onto polymer (Fe-PET) and glass (Fe-glass) substrates via DC magnetron sputtering (90 % Ar - 10 % N2 gas mixture). Polarization curves are obtained in 0.1 M Na2SO4 under ongoing Ar bubbling.

Film’s surface is covered with an oxide layer. Fe-PET films show lesser free surface energy in comparison with Fe-glass films (H2O wetting angle is θ = 77 ± 5° and θ = 87 ± 2°, which gives adhesion energy Wa = 89.1·10-3 J/m2 and Wa = 76.6·10-3 J/m2, respectively). Initial corrosion stage for films on the rigid substrate goes slower than for the polymer substrate: corrosion currents for oxide dissolution and stationary potentials are icorr = 5·10-7 A/cm2, and E0 = -0.050 V (vs SHE) for Fe-glass; icorr = 7·10-6 А/cm2, and E0 = -0.465 V for Fe-PET.

Film’s thickness influences corrosion rate, but rigidity of substrate does not. Increase in thickness results in increase in corrosion current: icorr = 1·10-5 А/cm2 for h = 150 nm, and icorr = 8·10-5 А/cm2 for h = 300 nm. Stationary, passivation and repassivation potentials for Fe-N films after oxide layer removal are E0 = -0.575 V, Epass = -0.500 V, and Erepass = +1.350 V. In the case of h = 150 nm, films show localized corrosion. In a passive state, Fe-glass films are more stable then Fe-PET films.

The phenomena observed are probably the results of a mechanical stresses within metal film[2]. In the case of flexible and plastic substrate these stresses are partially decreased due to sample bend. The rigid substrate produces mechanical stress excess which increases oxide layer thickness and increase initial corrosion durability.

The results reported are of practical interest for thin film devices.

Literature

1. S.S. Maklakov, S.A. Maklakov, I.A. Ryzhikov, K.N. Rozanov, A.V. Osipov, A.S. Naboko, V.A. Amelichev, S.V. Kulikov. The structure and microwave permeability of thin cobalt films. // Nanotechnologies in Russia. 7 (2012) 255-261

2. A.V. Agaponova, I.V. Bykov, S.A. Maklakov, S.S. Maklakov, A.A. Pukhov, I.A. Ryzhikov, M.V. Sedova, E.E. Shalygina, I.T. Yakubov. Visualization of the domain structure of ferromagnetic films using the magnetochemical effect. // Physics of the Solid State. 53 (2011) 1013-1016