IAM - Ceramic Materials and Technologies

Determination of stability areas of Yb- and Nd-alpha-SiAlON phases using the Rietveld method

  • Author:

    Herrmann, M.; Holzer, S.; Hoffmann, M. J.

  • Source:

    EURO CERAMICS VIII, PTS 1-3 264-268 (2004), 1075–1078 

  • Determination of stability areas of Yb- and Nd-alpha-SiAlON phases using the Rietveld method.

Abstract

A series of samples with ytterbium and neodymium containing alpha-SiAlON (Rx+vSi12 (m+n)Alm+nOnN16-n with R = Yb, Nd) have been synthesised at 1800degreesC. The Rietveld technique was used for the determination of the x value of the alpha-SiAlON modification. On the basis of these data, the stability regions of Yb- and Nd-alpha-SiAlONs were established. These results were compared with data obtained by other methods, e.g. XRD. The results show that the Rietveld method results in the most accurate data. This method offers the possibility to determine the boundaries of two phase field beta-SiAlON / alpha-SiAlON with a high accuracy. At n values less than 0.9, x values as low as 0.25 +/- 0.01 for Yb and 0.30 +/- 0.01 for Nd-alpha-SiAlON were observed. This is a evidence that the solubility area of the Yb-alpha-SiAlON is extended to lower x values than those suggested in the literature.