Phase Equilibria and Ordering in the System ZrO ₂ ‐CaO

Abstract

The phase diagram of the system ZrO 2 ‐CaO for the region ZrO 2 ‐CaZrO 3 was redetermined. The extent of the cubic solid solution field was ascertained by using a high‐temperature X‐ray furnace, precise lattice parameter measurements, and a hydrothermal technique. At 850 ± 150°C, the cubic solid solutions decompose by a eutectoid reaction. A reasonable agreement for the position of the eutectoid in this system was obtained by comparing the extrapolated data from high temperatures with the data obtained by the hydrothermal technique. Only one ordered compound, CaZr 4 O 9 , with monoclinic symmetry, was found; this compound is unstable above 1310 ± 40°C.