The design of compositions for multi-cation doped α-β SiAlON ceramics by the Rietveld method

Although densification of α-β-SiAlON ceramics is easier by using sintering additives, it is difficult to achieve the designed composition and therefore the mechanical properties after sintering. This is mainly due to the stability regions of α-SiAlONs which are related to cation size of the rare earth. In the present work, α-β-SiAlON starting composition was densified by gas pressure sintering using oxides of Nd₂O₃, Y₂O₃ and equimolar mixture of Nd₂O₃-Y₂O₃. The Rietveld technique was used for characterisation of the diffraction pattern and calculation of lattice parameters of α-SiAlON. On the basis of obtained data, the stability regions of Y, Nd and Y-Nd doped α-SiAlONs were established. The Rietveld results were further confirmed the previous results obtained by classical XRD technique that the stability region for Nd-Y multi-cation doped α-SiAlON is larger than Nd- doped system.