Iron oxide-based nanostructured ceramics with tailored magnetic and mechanical properties: development of mechanically robust, bulk superparamagnetic materials

Giuntini, Diletta; Torresani, Elisa; Chan, Kyle; Blankenburg, Malte; Saviot, Lucien; Bor, Büsra; Domènech, Berta; Shachar, Meir H.; Müller, Martin; Olevsky, Eugene A.; Garay, Javier E.; Schneider, Gerold A.

doi:10.1039/c9na00222g

Cited by 30 publications

(39 citation statements)

References 78 publications

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“…The homogeneous SC materials were heat-treated at 250 and 325 °C, instead of 350 °C. This is decided based on a previous small-angle x-ray scattering (SAXS) analysis [ 27 ], revealing that in certain material batches—typically with slightly lower organic content or particle size—localized sintering onset can occur already at 350 °C (the high surface energy of the NP makes them extremely prone to densification). To avoid undesired nanostructure alterations, a slightly lower maximum HT temperature was applied here to the nanocomposites with low organic content.…”

Section: Methodsmentioning

confidence: 99%

“…Supercrystalline arrangements enable a variety of emergent functionalities [ 20 , 22 ], but also the production of bricks that are very suitable to build hierarchical structural materials. Even though initially developed in micro-sizes and featuring relatively low mechanical properties [ 23 , 24 ], recent progress has been made towards the production of bulk macro-scale supercrystalline ceramic-organic nanocomposites, with mechanical properties boosted thanks to an annealing-induced crosslinking of the organic phase [ 19 , 25 , 26 , 27 , 28 , 29 ].…”

Section: Introductionmentioning

confidence: 99%

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Mapping the Mechanical Properties of Hierarchical Supercrystalline Ceramic-Organic Nanocomposites

et al. 2020

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Multiscale ceramic-organic supercrystalline nanocomposites with two levels of hierarchy have been developed via self-assembly with tailored content of the organic phase. These nanocomposites consist of organically functionalized ceramic nanoparticles forming supercrystalline micron-sized grains, which are in turn embedded in an organic-rich matrix. By applying an additional heat treatment step at mild temperatures (250–350 °C), the mechanical properties of the hierarchical nanocomposites are here enhanced. The heat treatment leads to partial removal and crosslinking of the organic phase, minimizing the volume occupied by the nanocomposites’ soft phase and triggering the formation of covalent bonds through the organic ligands interfacing the ceramic nanoparticles. Elastic modulus and hardness up to 45 and 2.5 GPa are attained, while the hierarchical microstructure is preserved. The presence of an organic phase between the supercrystalline grains provides a toughening effect, by curbing indentation-induced cracks. A mapping of the nanocomposites’ mechanical properties reveals the presence of multiple microstructural features and how they evolve with heat treatment temperature. A comparison with non-hierarchical, homogeneous supercrystalline nanocomposites with lower organic content confirms how the hierarchy-inducing organic excess results in toughening, while maintaining the beneficial effects of crosslinking on the materials’ stiffness and hardness.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Mapping the Mechanical Properties of Hierarchical Supercrystalline Ceramic-Organic Nanocomposites

et al. 2020

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“…Because of the large scale of our processing routine, supercrystal nucleation is expected at multiple locations, and the subsequent contact of the various seeds is at the origin of the development of multiple types of interfaces. An additional source of imperfections is the unavoidable size scatter of the constituent nanoparticles (a size scatter of >20% often leads to "superamorphous" structures) (8). Figure 1A shows a supercrystalline area with uniform orientation, with a photograph of the respective bulk pellet in the inset.…”

Section: Supercrystalline Nanocomposites' Processing and Nanostructurementioning

confidence: 99%

Defects and plasticity in ultrastrong supercrystalline nanocomposites

et al. 2021

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Supercrystalline nanocomposites are nanoarchitected materials with a growing range of applications but unexplored in their structural behavior. They typically consist of organically functionalized inorganic nanoparticles arranged into periodic structures analogous to crystalline lattices, including superlattice imperfections induced by processing or mechanical loading. Although featuring a variety of promising functional properties, their lack of mechanical robustness and unknown deformation mechanisms hamper their implementation into devices. We show that supercrystalline materials react to indentation with the same deformation patterns encountered in single crystals. Supercrystals accommodate plastic deformation in the form of pile-ups, dislocations, and slip bands. These phenomena occur, at least partially, also after cross-linking of the organic ligands, which leads to a multifold strengthening of the nanocomposites. The classic shear theories of crystalline materials are found to describe well the behavior of supercrystalline nanocomposites, which result to feature an elastoplastic behavior, accompanied by compaction.

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“…Solid-solid interfaces are ubiquitous in materials science and engineering with wideranging properties and applications [1,2]. In polycrystalline bulk materials and thin films, interfaces directly impact mechanical, optical, thermal, magnetic, electrical and (electro)chemical properties due to existence of local heterogeneity in structure, composition, chemistry, and electronic structure down to the atomic scale [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16]. Ceramics such as oxides [4,17] are particularly prone to GB effects as annealing the GBs out by coarsening the grains usually requires ≥1000 • C, which is energy-intensive, costly, and deteriorates device components.…”

Section: Introduction 1background and Motivationmentioning

confidence: 99%

A Review of Grain Boundary and Heterointerface Characterization in Polycrystalline Oxides by (Scanning) Transmission Electron Microscopy

et al. 2021

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Interfaces such as grain boundaries (GBs) and heterointerfaces (HIs) are known to play a crucial role in structure-property relationships of polycrystalline materials. While several methods have been used to characterize such interfaces, advanced transmission electron microscopy (TEM) and scanning TEM (STEM) techniques have proven to be uniquely powerful tools, enabling quantification of atomic structure, electronic structure, chemistry, order/disorder, and point defect distributions below the atomic scale. This review focuses on recent progress in characterization of polycrystalline oxide interfaces using S/TEM techniques including imaging, analytical spectroscopies such as energy dispersive X-ray spectroscopy (EDXS) and electron energy-loss spectroscopy (EELS) and scanning diffraction methods such as precession electron nano diffraction (PEND) and 4D-STEM. First, a brief introduction to interfaces, GBs, HIs, and relevant techniques is given. Then, experimental studies which directly correlate GB/HI S/TEM characterization with measured properties of polycrystalline oxides are presented to both strengthen our understanding of these interfaces, and to demonstrate the instrumental capabilities available in the S/TEM. Finally, existing challenges and future development opportunities are discussed. In summary, this article is prepared as a guide for scientists and engineers interested in learning about, and/or using advanced S/TEM techniques to characterize interfaces in polycrystalline materials, particularly ceramic oxides.

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Iron oxide-based nanostructured ceramics with tailored magnetic and mechanical properties: development of mechanically robust, bulk superparamagnetic materials

Abstract: A novel routine is developed to produce nanostructured ceramic-based composites with enhanced mechanical properties and tailored magnetic behavior.

Cited by 30 publications

References 78 publications

Mapping the Mechanical Properties of Hierarchical Supercrystalline Ceramic-Organic Nanocomposites

Mapping the Mechanical Properties of Hierarchical Supercrystalline Ceramic-Organic Nanocomposites

Defects and plasticity in ultrastrong supercrystalline nanocomposites

A Review of Grain Boundary and Heterointerface Characterization in Polycrystalline Oxides by (Scanning) Transmission Electron Microscopy

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