Local structure of pre-alloyed Al/Y/SiCN nanopowders studied by XAS at the Al K-edge using fluorescence yield detection

As the processing of Si sub 3 N sub 4 dense ceramics by sintering is promoted by using additives such as Al sub 2 O sub 3 and Y sub 2 O sub 3 , the possibility to introduce these compounds in the starting SiCN powder is explored by adding appropriate precursors like Al and Y isopropoxydes. The fluorescence yield detection is used at the Al K-edge to describe the local structure around this element in these as-prepared pre-alloyed new phases as well as its evolution during annealing under nitrogen. Results are compared with that of reference amorphous and crystalline phases. With annealing Al local structure shows an evolution towards that of crystalline AlN, while the presence of other different disordered sites like AlO sub 4 and AlN sub 3 O cannot be excluded.