Keatite stuffed

Rgure 1-13 Thermal expansion behavior of p-spodumene solid solution (stuffed keatite) crystals (Li20 Al203nSi02) along tetragonal axes (after Ostertag et al., 1968). 

As in the case of P-quartz, the Li ion can also be replaced by Mg in P-spodumene, a stuffed derivative of keatite. The degree of substitution, however, is lower than that of P-quartz. 

Invariably, however, the hexagonal quartz crystals will transform to the stable tetragonal phase P-spodumene, or as it is sometimes referred to, stuffed keatite. This phase transformation is isochemical with compositions along... 

The high-quartz and keatite-type alumino-silicates are such stuffed derivatives. Both types of framework are relatively dense, compared with, for example, those of tridymite and cristobalite. Therefore, only small univalent or divalent M ions can be accomodated in their cavities, Li ions being typical. Indeed, solid solutions of the composition LiAlSi 02x4-2 exist with both types of framework over wide ranges of x. 

Based on stuffed )3-quartz or j3-spodumine (keatite) soUd solutions... 

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