range of composition on the LiTaO 3 -CaZrO 3 join for tem-A new long period, anion-deficient, fluorite-related super-peratures ranging between 1100 and 1350ЊC. Examination structure phase (a ؍ 36.372(3), b ؍ 7.3590(5), and c ؍ 31.018(8) of these specimens via X-ray powder diffraction and trans-A ˚) has been discovered in the CaO-ZrO 2 -Ta 2 O 5 system at an mission electron microscopy (TEM) gave results that were experimentally determined composition of 0.304(4)TaO 2.5 ؒ only partially in agreement with the earlier reported re-0.347(4)ZrO 2 ؒ 0.349(4)/CaO. Electron diffraction suggests a sults-in particular a previously unreported, fluoritespace group symmetry for this phase of Fddd. It is furthermore related, superstructure phase was clearly present in all shown that substantial amounts of Ta 2 O 5 can be incorporated specimens from 45 to 90 mol% CaZrO 3 in addition to the into CaZrO 3 without apparently altering structure type. Exwide range solid solution phase reported by Neurgaonkar tremely sluggish kinetics, however, make it difficult to deteret al.
(1) and Smith and West (2).
mine the extent of this perovskite-related solid solution.