Axial Thermal Expansion of TetragonaI ZrO, Between 1150° and 1700°C

The lattice constants for three samples of tetragonal ZrO 2 were measured in a high‐temperature X‐ray diffractometer in the range 1150° to 1700°C in an ambient air atmosphere. The unrefined lattice constants were the same for these materials only after each had been previously heat‐treated at 1550° to 1750°C in an ambient air atmosphere. The thermal expansions of the two axes are linear and are given by: a value, A = 3.588 2 + 4.50 X 10+(T) , within 0.001 3 A; and c value, A = 5.188 2 + 7.57 × 10 −5 (T), within 0.002 2 A, where T is in °C for the range 1150° to 1700°C. The lattice constant values are a = 3.639 9 A and c = 5.275 8 A at 1150°C and a = 3.678 2 A and c = 5.339 7 A at 1700°C.