Experimental and Theoretical Investigation of the Elastic Properties of HfV2O7

Anna L Ravensburg,Denis Music,Jochen M Schneider,Philipp Keuter,Danilo J Miljanovic

doi:10.3390/cryst10030172

Abstract

We investigated the elastic properties of the HfV2O7 high-temperature phase, exhibiting negative thermal expansion, in a synergetic strategy of first-principle calculations and nanoindentation experiments performed on sputtered films. Self-consistent results were obtained for the measured elastic modulus (73 ± 14 GPa) and dispersion-corrected density functional theory calculations. The elastic properties of HfV2O7 are affected by long-range dispersion interaction, which may be induced by severe modification in the second-nearest neighbor O-O bond distance as obtained upon compression. HfV2O7 is composed of HfO6, VO4, and V2O7 building blocks, whereby the latter is characterized by an increasing V-O(-V) bond length upon compression.

Highlights

Near-zero expansion composites are contrived for applications in environments with rapidly changing temperatures to guarantee unaltered material performance [1,2,3,4]
For the application of HfV2 O7 in a composite, understanding its elastic behavior is important for multiple reasons: the elastic properties of an Negative thermal expansion (NTE) phase used in a composite determine the overall elastic properties of the composite [12], and its mechanical response in rapid heating or cooling processes which induce thermal stress due to the different coefficients of thermal expansion [13]
The work aimed to study the elastic properties of the HT phase of HfV2 O7, exhibiting NTE, in a synergetic strategy using both, ground state density functional theory (DFT) calculations and nanoindentation experiments on sputtered HfV2 O7 thin films

Summary

Introduction

Near-zero expansion composites are contrived for applications in environments with rapidly changing temperatures to guarantee unaltered material performance [1,2,3,4]. NTE is only reported for the HT phase [6,7,9], which is reasoned by phonon modes involving translational and librational movements of the quasi-rigid octahedral HfO6 and tetrahedral VO4 units [7,9]. These translations and librations substantially soften upon compression of the lattice which leads to its thermal compression [7,9]. HfV2 O7 thin films were synthesized and nanoindentation experiments were carried out to validate the theoretical predictions

Computational and Experimental Details

Results and Discussion

Conclusions