2005/09/08 by Cristian Pantea, C. Pantea, Pantea, C. +18
Engineering · Materials Science · Physics and Astronomy · #Advanced Battery Materials and Technologies #FOS: Physical sciences #Materials Science (cond-mat.mtrl-sci) #Thermal Expansion and Ionic Conductivity #Thermodynamic and Structural Properties of Metals and Alloys #cond-mat.mtrl-sci
paper · pdf · doi:10.48550/arxiv.cond-mat/0509220
11 PAGES, 4 FIGURES, 1 TABLE
arxiv created 2005/09/08 · openalex publication_date 2005/09/08 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The negative thermal expansion (NTE) compound ZrW2O8 has been well-studied because it remains cubic with a nearly constant, isotropic NTE coefficient over a broad temperature range. However, its elastic constants seem just as strange as its volume because NTE makes temperature acts as positive pressure, decreasing volume on warming and, unlike most materials, the thermally-compressed solid softens. Does ZrW2O8 also soften when pressure alone is applied? Using pulse-echo ultrasound in a hydrostatic SiC anvil cell, we determine the elastic tensor of monocrystalline ZrW2O8 near 300 K as a function of pressure. We indeed find an unusual decrease in bulk modulus with pressure. Our results are inconsistent with conventional lattice dynamics, but do show that the thermodynamically-complete constrained-lattice model can relate NTE to elastic softening as increases in either temperature or pressure reduce volume, establishing the predictive power of the model, and making it an important concept in condensed-matter physics.