Local vibrations and negative thermal expansion in ZrW2O8
F Bridges1, T Keiber1, P Juhas2
1Department of Physics, University of California, Santa Cruz, California 95064, USA.
Abstract:
We present an x-ray pair distribution function (XPDF) analysis and extended x-ray absorption fine structure (EXAFS) data for ZrW2O8 (10-500 K) with a focus on the stiffness of the Zr-O-W linkage. The XPDF is highly sensitive to W-Zr and W-W correlations, but much less so to O-O or W-O correlations. The Zr-W peak in the XPDF data has a weak temperature dependence and, hence, this linkage is relatively stiff and does not permit bending of the Zr-O-W link. We propose that the low energy vibrational modes that lead to negative thermal expansion involve correlated rotations of ZrO6 octahedra that produce large <111> translations of the WO4 tetrahedra, rather than a transverse motion of O atoms that imply a flexible Zr-O-W linkage.
More Related Videos
07:44Characterization of Full Set Material Constants and Their Temperature Dependence for Piezoelectric Materials Using Resonant Ultrasound Spectroscopy
Published on: April 27, 2016
08:18Synthesis and Characterization of High c-axis ZnO Thin Film by Plasma Enhanced Chemical Vapor Deposition System and its UV Photodetector Application
Published on: October 3, 2015
Related Concept Videos
Thermal Strain
Thermal expansion and Thermal stress: Problem Solving
To solve the problem, first, identify the known and unknown quantities. The initial length (L) of the bridge is 1275 m, the coefficient of linear expansion (α) for steel is 12 x 10-6/°C, and the change in temperature (ΔT) is 55...
Expansion and Contraction in Masonry Walls
To...
Thermal Expansion
Imperfections in Crystal Structure: Non-Stoichiometric Defects
Imperfections in Crystal Structure: Stoichiometric Point Defects
