Axial thermal expansion of ZrO₂ and HfO₂ in the range room temperature to 1400°C

The axial thermal expansion of monoclinic and tetragonal ZrO₂ and of monoclinic HfO₂ was studied over the temperature range from room temperature to 1400 °C. The linear thermal expansion coefficients were calculated. Thermal expansion along (x 10⁶ per °C) a = 10.31 monoclinic ZrO₂, 11.60 tetragonal ZrO₂, 9.34 monoclinic HfO₂; b = 1.35 monoclinic ZrO₂, - tetragonal ZrO₂, 2.98 monoclinic HfO₂; c = 14.68 monoclinic ZrO₂, 16.08 tetragonal ZrO₂, 13.10 monoclinic HfO₂. Some aspects of the present study, such as anisotropy of thermal expansion and a pretransformation vibrational anomaly, are discussed briefly.