High pressure behaviour and elastic properties of a dense inorganic–organic framework. Issue 10 (27th November 2015) - Feng, Guoqiang
Abstract : The hydrostatic behaviour of a cubic dense inorganic–organic framework [DABCOH2 2+ ][K(ClO4 )3 ] has been systematically studied via high-pressure synchrotron X-ray powder diffraction. Further first principles calculations of full elastic tensors give full mapping of the Young's moduli, shear moduli and Poisson's ratios of this material. Abstract : The high pressure behaviour of a cubic dense inorganic–organic framework [DABCOH2 2+ ][K(ClO4 )3 ] (DABCOH2 2+ = diazabicyclo[2.2.2]octane-1, 4-diium) has been systematically studied via synchrotron X-ray powder diffraction, over the range of 0–3.12 GPa. The framework [DABCOH2 2+ ][K(ClO4 )3 ] shows a more rigid response, with a bulk modulus of 30(1) GPa and an axial compressibility of 7.6(4) × 10 −3 GPa −1, compared with ZIF-8 and the dense hybrid solar cell perovskite CH3 NH3 PbI3 . Density functional theory calculations reveal that the structural change in [DABCOH2 2+ ][K(ClO4 )3 ] is attributed to the contraction of the KO12 polyhedra, which consequently results in the rotation of the perchlorate linkers and synergistic movement of the DABCOH2 2+ guest. Further extensive theoretical calculations of full elastic tensors give full mapping of the Young's moduli, shear moduli and Poisson's ratios of [DABCOH2 2+ ][K(ClO4 )3 ], which are in the range of 31.6–36.6, 12.3–14.6 GPa and 0.2–0.32, respectively. The Young's and shear moduli of [DABCOH2 2+ ][K(ClO4 )3 ] are larger than those of cubic MOF-5, ZIF-8 and CH3 NH3 PbI3 . In addition, the narrow range of Poisson's ratios in [DABCOH2 2+ ][K(ClO4 )3 ] indicates its very isotropic nature in response to biaxial stress.