Crystal structure of dehydrated wairakite

Single-crystal X-ray analysis was employed to study dehydrated wairakite Ca0.97Na0.06K0.03 x [Al1.95Si4.04O12 ] with the following parameters: a = 18.260(4) (A) over cap, b = 18.284(4) (A) over cap, c = 13.432(3) (A) over cap, beta = 90.28(3)degrees,. V = 4989(3) (A) over cap (3), Z = 16, space group B2(1)/d. A comparison was carried out with the structure of the high,high-temperature (600degreesC) phase, space group I4(1)/acd. The coordination of the Ca cations increased from, 4 to 4 + 1. Additional ligands were acquired from, the four-member ring of the framework, upon its deformation and a pairwise countershift of the cations along the c axis. This resulted in a pseudotetragonal unit cell with. a doubled volume and lowered symmetry.