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A new approach to metal surface nitriding using dielectric barrier discharge (DBD) plasma at atmospheric pressure is presented in this paper. Results of the study show that the plasma nitriding at atmospheric pressure using DBDs is realizable. Harder and thicker compound layer and diffusion layer on the treated surface has been formed in shorter treatment time comparing with the conventional vacuum plasma nitriding, Increasing the applied voltage will facilitate the formation of a thicker nitrided layer using the DBD. The nitrided layer acquired by this new approach is mainly composed of ε phase and γ phase, and the crystal grains of the ε phase is fine and has high dislocations density.KEY WORDS: Dielectric barrier discharge; plasma nitriding at atmospheric pressure; non-equilibrium plasma.

Thin films of RE0.5Sr0.5CoO3-δ (RE=La, Pr, Nd) nominal composition were grown on yttria-stabilized zirconia (YSZ) single crystal substrates by ion-beam sputtering deposition method. The X-ray diffraction spectra and X-ray photoelectron spectroscopy were measured for RE0.5Sr0.5CoO3-δ thin films with perovskite structure. The experimental results indicate that the average grain size of RE0.5Sr0.5CoO3-δ thin films ranges from 86 to 165 nm，and the film obtained by heat-treating at 750 °C is highly oriented . The RE0.5Sr0.5CoO3-δ thin films being mixed-valent systems contains Co3+ and Co4+ ions. There is oxygen vacancy at an interface region for RE0.5Sr0.5CoO3-δ thin films.