Abstract
Silver(I) hexacyanocobaltate(III), Ag3[Co(CN)6], shows a large negative linear compressibility (NLC, linear expansion under hydrostatic pressure) at ambient temperature at all pressures up to our experimental limit of 7.65(2) GPa. This behavior is qualitatively unaffected by a transition at 0.19 GPa to a new phase Ag3[Co(CN)6]-II, whose structure is reported here. The high-pressure phase also shows anisotropic thermal expansion with large uniaxial negative thermal expansion (NTE, expansion on cooling). In both phases, the NLC/NTE effect arises as the rapid compression/contraction of layers of silver atoms - weakly bound via argentophilic interactions - is translated via flexing of the covalent network lattice into an expansion along a perpendicular direction. It is proposed that framework materials that contract along a specific direction on heating while expanding macroscopically will, in general, also expand along the same direction under hydrostatic pressure while contracting macroscopically.
Original language | English |
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Pages (from-to) | 18708-18713 |
Number of pages | 6 |
Journal | Proceedings of the National Academy of Sciences of the United States of America |
Volume | 105 |
Issue number | 48 |
DOIs | |
State | Published - Dec 2 2008 |
Externally published | Yes |
Keywords
- Flexibility
- Framework materials
- High-pressure
- Negative linear compression
- Negative thermal expansion