Related Experiment Video
Updated: Dec 1, 2025

Atomic Layer Deposition of Vanadium Dioxide and a Temperature-dependent Optical Model
Published on: May 23, 2018
A Proposal for a Composite with Temperature-Independent Thermophysical Properties: HfV2-HfV2O7
Philipp Keuter1, Anna L Ravensburg1,2, Marcus Hans1
1Materials Chemistry, RWTH Aachen University, Kopernikusstr. 10, 52074 Aachen, Germany.
Abstract:
The HfV2-HfV2O7 composite is proposed as a material with potentially temperature-independent thermophysical properties due to the combination of anomalously increasing thermoelastic constants of HfV2 with the negative thermal expansion of HfV2O7. Based on literature data, the coexistence of both a near-zero temperature coefficient of elasticity and a coefficient of thermal expansion is suggested for a composite with a phase fraction of approximately 30 vol.% HfV2 and 70 vol.% HfV2O7. To produce HfV2-HfV2O7 composites, two synthesis pathways were investigated: (1) annealing of sputtered HfV2 films in air to form HfV2O7 oxide on the surface and (2) sputtering of HfV2O7/HfV2 bilayers. The high oxygen mobility in HfV2 is suggested to inhibit the formation of crystalline HfV2-HfV2O7 composites by annealing HfV2 in air due to oxygen-incorporation-induced amorphization of HfV2. Reducing the formation temperature of crystalline HfV2O7 from 550 °C, as obtained upon annealing, to 300 °C using reactive sputtering enables the synthesis of crystalline bilayered HfV2-HfV2O7.
Related Concept Videos
Equation of State
Thermodynamic Potentials
Temperature and Thermal Equilibrium
The concept of temperature has evolved from the common concepts of hot and cold. The scientific definition of temperature explains more than just our sense of hot and cold. Temperature is operationally defined as the quantity measured with a thermometer. Furthermore, temperature is...
Heat Capacities of an Ideal Gas II
Heat Capacities of an Ideal Gas III
Properties of Transition Metals

