The linear thermal expansion of stoichiometric 239PuO2 was measured from 25 to 1420°C. A polynomial least-squares fit of the expansion data yielded the linear expansion expression [in cm/ (cm °C)]:

ΔL/Lo =−1.2232 × 10−4 + 7.5866 × 10−6 T
+ 5.6948 × 10−9 T2 − 5.9768 × 10−12 T3
+ 4.4092 × 10−15 T4 − 1.2897 × 10−18 T5.

The mean linear expansion coefficient from 25 to 1420° C was 11.16 × 10−6 cm/(cm °C).