Thickness dependent phase transformations in implanted iron layers

This article shows that phase transformations in implanted iron may strongly depend on the sample thickness. The effect essentially relies on lower impurity concentration required for given phase formation in thin films as compared with thick layers or bulk samples. The phase transformation in thin films is also more complete. In this work the total transformation of pure iron into iron nitrides was observedn upon nitrogen implantation of thin iron layers, whereas about 20 % of Fe atoms remains in crystalline a-Fe phase in nitrogen-implantedin bulk samples.