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Item type:Publication, Access status: with files , Defect migration in supercrystalline nanocomposites(American Chemical Society (ACS), 2025-12-16); ; ; ; Supercrystalline nanocomposites (SCNCs) are nanostructured hybrid materials with a variety of unique functional properties. Given their periodically arranged building blocks, they also offer interesting parallels with crystalline materials. They can be processed in multiple forms and at different scales, and cross-linking their organic ligands via heat treatment leads to a boost of their mechanical properties. This study shows, via X-ray and in situ scanning transmission electron microscopy (STEM) analyses, how each of these processing steps plays a distinct role in the generation, migration, interaction, and healing of supercrystalline defects. Pressing of SCNCs into bulk pellets leads to a distortion of the otherwise fcc superlattice, while emulsion-templated self-assembly yields supraparticles (SPs) with stacking faults and size-dependent symmetries. Heat treatment at the same temperatures as those applied for the organic cross-linking has significant effects on planar defects. Stacking faults migrate and get healed, as also confirmed via molecular dynamics simulations, and intersupercrystalline “grain” boundaries migrate via anisotropic motion of disconnections. These rearrangements of defects at the supercrystalline scale (tens of nanometers) in nanocomposites with high mechanical properties (compressive strength of 100–500 MPa) provide insights into the formation and evolution of ordered assemblies of functionalized nanoparticles.Publicationtype: Journal Article41 14 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , In situ compression of ceramic-organic supraparticles: Deformation and fracture behavior(Elsevier, 2025-10-01); ; ; ; Supercrystalline nanocomposites (SCNCs) feature intriguing functionalities and exceptional mechanical properties, but they are usually confronted with challenges when it comes to processing them in larger bulk form. One way to tackle this problem is a hierarchical approach, for which spherical SCNCs, i.e. supraparticles (SPs), are promising candidates as building blocks. Understanding the mechanical behavior of SPs is thus a key step towards the development of robust, multifunctional and macroscopic SCNCs. Hereby, in situ compression tests are performed on SPs with varying sizes and levels of crosslinking of their organic ligands. A size-dependent deformation and fracture behavior emerges. Plasticity occurs in larger SPs, while small ones exhibit brittle fracture. Surface stress and compaction affect the elastic modulus. Fracture initiation sites shift from the center of SPs to their equatorial belts with the decrease of SPs’ size. The inverse scaling relationship between fracture strength and SPs’ sizes is rationalized via Griffith theory.Publicationtype: Journal Article17 12 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Nanofatigue of supercrystalline nanocompositesSupercrystalline nanocomposites (SCNCs) are a new category of hybrid materials consisting of inorganic nanoparticles surface-functionalized with organic ligands and with periodic nanostructures, featuring multi-functionality and able to reach exceptional mechanical properties. Although efforts have been made to explore their mechanical behavior, their response to cyclic loading remains to be unveiled. Here, the fatigue behavior of SCNCs with different degrees of organic crosslinking is investigated via nanoindentation. The nanocomposites’ fatigue life is assessed, and it emerges that SCNCs without crosslinking are more efficient in dissipating energy under cyclic loading and thus feature a longer fatigue life. Chipping is identified as the main fatigue failure mechanism, whereas different mechanisms, intrinsic or extrinsic, dominate in the indentation depth propagation, again depending on crosslinking.Publicationtype: Journal Article14 139 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Nanoindentation creep of supercrystalline nanocomposites(Elsevier, 2023-07); ; ; ; Supercrystalline nanocomposites (SCNCs) are inorganic-organic hybrid materials with a unique periodic nanostructure, and thus they have been gaining growing attention for their intriguing functional properties and parallelisms with hierarchical biomaterials. Their mechanical behavior remains, however, poorly understood, even though its understanding and control are important to allow SCNCs’ implementation into devices. An important aspect that has not been tackled yet is their time-dependent deformation behavior, which is nevertheless expected to play an important role in materials containing such a distribution of organic phase. Hereby, we report on the creep of ceramic-organic SCNCs with varying degrees of organic crosslinking, as assessed via nanoindentation. Creep strains and their partial recoverability are observed, hinting at the co-presence of viscoelasticity and viscoplasticity, and a clear effect of crosslinking in decreasing the overall material deformability emerges. We rationalize our experimental observations with the analysis of stress exponent and activation volume, resulting in a power-law breakdown behavior and governing deformation mechanisms occurring at the organic sub-nm interfaces scale, as rearrangement of organic ligands. The set of results is reinforced by the evaluation of the strain rate sensitivity via strain rate jump tests, and the assessment of the effect of oscillations during continuous stiffness measurement mode.Publicationtype: Journal ArticleScopus© Citations 4 19 320 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Nanoindentation of supercrystalline nanocomposites: linear relationship between elastic modulus and hardness(Springer, 2022-04-15); ; ; ; Supercrystalline nanocomposites (SCNCs) are a new category of nanostructured materials, with organically functionalized nanoparticles assembled into periodic structures, reminiscent of atomic crystals. Thanks to this nanoarchitecture, SCNCs show great promise for functional applications, and understanding and controlling their mechanical properties becomes key. Nanoindentation is a powerful tool to assess the mechanical behavior of virtually any material, and it is particularly suitable for studies on nanostructured materials. While investigating SCNCs in nanoindentation, a linear proportionality has emerged between elastic modulus and hardness. This is not uncommon in nanoindentation studies, and here we compare and contrast the behavior of SCNCs with that of other material categories that share some of the key features of SCNCs: mineral-rich biocomposites (where mineral building blocks are packed into a protein-interfaced network), ultrafine grained materials (where the characteristic nano-grain sizes are analogous to those of the SCNC building blocks), and face-centered cubic atomic crystals (which share the typical SCNC periodic structure). A strong analogy emerges with biomaterials, both in terms of the hardness/elastic modulus relationship, and of the correlation between this ratio and the dissipative mechanisms occurring upon material deformation. Insights into the suitability of SCNCs as building blocks of the next-generation hierarchical materials are drawn.Publicationtype: Journal ArticleScopus© Citations 10 62 101