Polytypoid sialons

AIO5 groups in the precursor results from the replacement of alkoxy groups by hydrazide species, and once formed, AIO5 appears to facilitate the incorporation of nitrogen during heat treatment (Kim et al. 2000). 

Of the various known structures for the extensive series of compounds of Si, Al, O and N (the sialons), those most closely related to AIN are the polytypoid sialons (Si,Al)m(0,N)m+i. The non-metal atoms in excess of the 1 1 ratio required by the 

---

Figure 5.35. Typical Al MAS NMR spectra of sialons. A. 21R polytypoid sialon. B. p-sialon, z = 2.7, C. O-sialon, x = 0.24, D. X-sialon. Asterisks indicate spinning side bands. Spectra A-C from Sjoberg et al. (1992), by permission of the Royal Society of Chemistry. Spectrum D...

Thompson DP, Korgul P, Hendry A (1983) The structural characterisation of SiAlON Polytypoids. In Riley FL (ed) Progress in Nitrogen Ceramics. NATO ASI Ser E 65. Kluwer Acad Publ, Dordrecht, p 61... 

Fig. 22. Subsolidus phase relations in the Si,Al,Y/N, O system showing a series of compatibility tetrahedrons formed by a -sialon, j3 -SiA ON, and AIN polytypoids [34].

Figure 5.3 Undulating layers of base-shared tetrahedra in sialon polytypoid phases [10],...

In addition to the P-SiAlON phase, a number of other phases have also been observed in this system [18, 20] including X-phase, so-called because its stmcture was unknown O, i.e., silicon oxynitride with partial replacement of Si and N by A1 and O and six phases with ranges of homogeneity extending along lines of constant M X ratio between P and AIN. The phases based on a wurtzite-type stmcture have been characterised as polytypoids related to AIN [23]. The stmctures... 

---