Enthalpy and Volume Changes for m-t Phase Transition in HfO2
Poster Jan 09, 2007
Sergey V. Ushakov and Alexandra Navrotsky
HfO2 is a prospective material for application as high-temperature ceramic and (transformation toughening above 1100OC) 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.
The heating of soil during fires may result in organic matter loss. The ratio of combustion enthalpy of soil organic matter to the alpha-beta quartz transition enthalpy can be used to compare heated and unheated soil. This eliminates the need to weigh samples and is insensitive to differences in water content between heated and unheated soils, making possible in-situ applications in field sites.READ MORE