Large Negative Linear Compressibility in InH(BDC)₂ from Framework Hinging

Abstract

Materials with negative linear compressibility (NLC) counterintuitively expand along one specific direction coupled to the volume reduction when compressed uniformly. NLC with a large value is desired for compression and materials science. However, NLC is generally smaller than −20 TPa^–1. High-pressure X-ray diffraction experiments reveal that the β-quartz-like InH­(BDC)₂ generates an extreme NLC (−62.4 TPa^–1) by framework hinging. InH­(BDC)₂ is much safer and lower-cost than Au⁺/Ag⁺ and CN^–-containing materials that dominated the fields of large NLC. This work reconfirms that a negative thermal expansion flexible framework could likely exhibit large NLC. Moreover, a large NLC could be anticipated to arise from β-quartz-like or related frameworks composed of rigid linear ligands and flexible framework angles