Fig. 3: Fracture mechanism of ZIF-62 glass and comparison with other material families.

a Structural representation of the crack propagation in the precracked ZIF-62 glass upon increasing strain (ε). Colored spheres represent carbon (red), hydrogen (gray), nitrogen (green), and zinc (blue). b Enlarged view of the Zn–N bond before (left) and after breaking (right). c Comparison of theoretically predicted and experimental fracture toughness (K_Ic) for a range of glass and glass-ceramic materials. The theoretical prediction is explained in the text. Figure is adopted with data from ref. ⁴⁴, in addition to data for silicate and borate glasses⁵⁴, oxycarbide glass-ceramics⁴⁵, and the present ZIF-62 glass. All the experimental K_Ic values are from self-consistent methods such as SEPB, chevron notched beam, and surface cracked in flexure, with an error smaller than ±0.05 MPa m^0.5. d Relationship between fracture surface energy (γ) and Poisson’s ratio (ν) for a range of materials. Figure is adopted with the data from refs. ^48,49,62 and extended with additional data for metallic glasses^63,64,65,66, silicate glasses^67,68, borate glasses^69,70,71, chalcogenide glasses^70,72,73, phosphate glasses^70,74, fluoride glasses^68,70, oxycarbide glasses and glass ceramics⁴⁵, tellurite glass⁷⁰, and the present ZIF-62 glass. e Ashby plot of the relation between K_Ic and Young’s modulus (E) for a range of materials. The figure is adopted with data from ref. ⁷⁵ and extended with that of the present ZIF-62 glass. Source data are provided as a Source Data file.