Objective
HfO² is a prospective material for application as high-temperature ceramic and (transformation toughening above 1100^OC) high-K dielectric in integrated circuits (reducing leakage current compared with SiO. HfO² isostructural to zirconium oxide and undergo monoclinic-tetragonal and tetragonal-cubic translations with temperate.

High Temperature phases are not quenchable but can be obtained in high area samples. Monoclinic-tetragonal transition in hafnia is critical for its application. However, there are no thermochemical data on phase transitions in HfO² The objective of this works was to determine enthalpy and volume changes for m-t transition in HfO² by direct measurements.