ATOMIC CONFIGURATIONS AND LOCAL ORDER IN LASER-SYNTHESIZED SI, SI-N, SI-C, AND SI-C-N NANOMETRIC POWDERS, AS STUDIED BY X-RAY-INDUCED PHOTOELECTRON-SPECTROSCOPY AND EXTENDED X-RAY-ABSORPTION FINE-STRUCTURE ANALYSIS

The chemical bonding and local order in Si, Si-N, Si-C, and Si-C-N nanometric powders prepared by laser synthesis have been investigated by using two experimental methods. The local environment of Si, C, and N atoms have been studied by x-ray-induced photoelectron spectroscopy, from a detailed analysis of the Si 2p, C 1s, and N 1s core levels. Complementary information concerning the structural arrangement around Si atoms has been deduced from extended x-ray-absorption fine-structure analysis performed at the Si K edge. The results show that the Si and Si-C powders prepared with a 600 W laser power are pure, well-crystallized materials; the Si-N sample prepared with the same laser power has a disordered structure, although chemical order exists. For the composite samples, the results reveal that, in particular preparation conditions, a local C-Si-N3 structure is formed.