Compositional inhomogeneity and tuneable thermal expansion in mixed-metal ZIF-8 analogues

DOI: 10.1039/C8CC04172E

Authors: Adam F. Sapnik (University of Oxford) , Harry S. Geddes (University of Oxford) , Emily M. Reynolds (University of Oxford) , Hamish H.-m. Yeung (University of Oxford) , Andrew L. Goodwin (University of Oxford)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Chemical Communications , VOL 13

State: Published (Approved)
Published: August 2018
Diamond Proposal Number(s): 13284

Abstract: We study the structural and thermomechanical effects of cation substitution in the compositional family of metal–organic frameworks Zn1−xCdx(mIm)2 (HmIm = 2-methylimidazole). We find complete miscibility for all compositions x, with evidence of inhomogeneous distributions of Cd and Zn that in turn affect framework aperture characteristics. Using variable-temperature X-ray powder diffraction measurements, we show that Cd substitution drives a threefold reduction in the magnitude of thermal expansion behaviour. We interpret this effect in terms of an increased density of negative thermal expansion modes in the more flexible Cd-rich frameworks.

Subject Areas: Chemistry


Instruments: I11-High Resolution Powder Diffraction