Powder X-Ray Data for Synthetic Anhydrous Sodium Zirconium Silicates

Abstract A systematic survey of phase formation in the Na 2 O-ZrO 2 -SiO 2 system has revealed inconsistencies in the number and identity of ternary phases, and of their X-ray powder data. The phases Na 2 ZrSiO 5 , Na 4 Zr 2 Si 3 O 12 , Na 2 ZrSi 2 O 7 and Na 2 ZrSi 4 O 11 were prepared by solid-state reaction and their experimental X-ray diffraction patterns measured. Calculated X-ray diffraction patterns were generated by computer, using published crystallographic data, and critically compared with the experimentally observed values. The unit-cell constants were redefined to a greater accuracy than the presently accepted values published in the Powder Diffraction File. Only Na 4 Zr 2 Si 3 O 12 produced an X-ray diffraction pattern which agreed with that previously published; those from the other phases were significantly different in both the intensities and positions of the reflections. Data for synthetic Na 2 ZrSi 4 O 11 identical to the mineral vlasovite are reported.