Latest Posters

Study of CO2 Adsorption on Amorphous HfO2 using PTA on the Netzsch 449
Sergey Ushakov and Alexandra Sergey , UC Davis

HfO2 is a prospective high-k replacement for SiO2 for future integrated circuits. We study energetic of amorphous and nanocrystalline hafnium oxide by high temperature oxide melt solution calorimetry to establish critical sizes where phase stability switches by surface energy terms.

Thermochemical Study of the Relations of the Monazite and Zircon Structures in the Rare-earth Orthophosphates
Sergey Ushakov and Alexandra Navrotsky, University of California

Existence of both zircon- and monazite-type polymorphs for Dy, Tb and Gd
orhtophosphates has been previously reported, however, available structural and thermodynamic data are scarce. The goal of this work was to evaluate the energetics of structural changes in these compounds.

Enthalpy and Volume Changes for m-t Phase Transition in HfO²
Sergey V. Ushakov and Alexandra Navrotsky, University of California

HfO² is a prospective material for application as high-temperature ceramic and high-K dielectric in integrated circuits. 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.

U C Davis Thermochemistry Facility
Alexandra Navrotsky, University of California

Brief descriptions and schematic diagrams of custom built Tian-Calvet type calorimeters and techniques of high-temperature oxide melt solution calorimetry are presented together with specifications of commercial calorimeters and thermal analysis equipment being used in the Facility.

Also presented are research examples include study of thermochemistry of iron oxides and TiO2 polymorphs using high-temperature oxide melt solution calorimetry and in-situ study of zeolite growth using Setaram C80

High temperature oxide melt solution calorimetry of PrO₂ and Pr₆O₁₁
Sergey V. Ushakov and Alexandra Navrotsky, University of California at Davis

The goal of this work was to synthesize praseodymium dioxide and obtain its drop solution enthalpy to use for calculation of formation enthalpies of Pr4+ compounds from calorimetry.

Gas Adsorption Microcalorimetry: Probing Energetics of Oxide Surfaces
Sergey V. Ushakov and Alexandra Navrotsky, University of California at Davis

As the dimensions decrease, surface properties become an overriding feature controlling reactivity and phase transformations in nanophases. The control of properties of solid surfaces is of paramount importance in a number of fields ranging from heterogeneous catalysis and fuel cells to microchip fabrication and corrosion-resistive coatings. Gas adsorption microcalorimetry is an unsurpassed method for providing information on surface energetics and reactivity.