Synthesis and reactivity of Fe nanoparticles embedded in a semi-insulatingmatrix

The technique of plasma enhanced chemical vapor deposition has been used to synthesize Fe nanoparticles in an amorphous boron carbide matrix. The nano particles range in size from approximately 0.7 to 4.5 nm. It has been demon strated that the size of the nanoparticles is proportional to the density o f the Fe precursor (ferrocene) in the vapor. The matrix films have been fou nd to be extremely hygroscopic. Upon absorption of moisture the films buckl e and delaminate from the Si substrate. The buckling is a consequence of in duced strain arising from the transformation of the Fe nanoparticles into a lpha-Fe2O3. The formation of alpha-Fe2O3 has been verified by electron diff raction and near edge x-ray absorption fine structure measurements. Examina tion of the magnetic properties of the alpha-Fe2O3 using the technique of m agnetic circular dichroism indicate that the nanoparticles are not ferromag netic. (C) 2000 American Institute of Physics. [S0021-8979(00)08609-6].