Structural phase transition of Na-substituted Cs-leucite compounds in the range 123–1173 K

(Cs,Na)-leucites, Cs1−XNaXAlSi2O6 (X=0.1, 0.2, 0.3), in which Cs+ ions were replaced by Na+ ions, were synthesized by a multistep heat treatment as a solid-state reaction. All the synthesized (Cs,Na)-leucites were well crystallized, which were identified as pollucite-related compounds. XRD study revealed that the (Cs,Na)-leucites were found to be undergo the structural phase transition of tetragonal to cubic in viewpoint of the splitting of the diffraction peak of the (800) plane of the synthesized (Cs,Na)-leucites. The structural phase transition was found to shift to lower temperatures with increasing amount of Na+ ions, without the change in the molar ratio of Al/Si in CsAlSi2O6.