Atomic force microscopy bending tests of a suspended rod-shaped object: Accounting for object fixing conditions.

The technique of atomic force microscopy (AFM) bending tests of a suspended nano-object (scroll, tube, rod) makes it possible to calculate the Young's modulus of the material it is made of based on experimental data. However, the calculation results involve a large error due to uncertain conditions (console or bridge) of fixing the test object. One of the ways to reduce this error is based on the theoretical consideration of consoles or bridges as beams with one or two ends resting on Winkler elastic foundations. The beam bending problems have been solved in both cases using Krylov's functions. This has allowed for developing an approach to the analytical identification of fixing conditions and including them in the calculations. The application of the approach is illustrated by AFM measurements of the Young's modulus of MgNi_{2}Si_{2}O_{5}(OH)_{4} nanoscrolls.

Titanium Oxyfluoride as a Material for Negative Electrodes of Lithium-Ion Batteries.

A study of the electrochemical characteristics of titanium oxyfluoride obtained with the direct interaction of titanium with hydrofluoric acid is reported. Two materials T1 and T2 synthesized under different conditions in which some TiF3 is formed in T1 are compared. Both materials exhibit conversion-type anode properties. Based on the analysis of the charge-discharge curves of the half-cell, a model is proposed according to which the first electrochemical introduction of lithium occurs in two stages: the first stage is the irreversible reaction resulting in a reduction in Ti4+/3+, and the second stage is the reversible reaction with a change in the charge state Ti3+/1.5+. The difference in material behavior is quantitative: T1 has a higher reversible capacity but lower cycling stability and a slightly higher operating voltage. The Li diffusion coefficient determined from the CVA data for both materials averages 1.2-3.0 × 10-14 cm2/s. A distinctive feature of titanium oxyfluoride anodes is the asymmetry in kinetic characteristics that revealed themselves during lithium embedding and extraction. In the long cycling regime, the excess of Coulomb efficiency over 100% was found in the present study.

Thermal Treatment Impact on the Mechanical Properties of Mg3Si2O5(OH)4 Nanoscrolls.

A group of phyllosilicate nanoscrolls conjoins several hydrosilicate layered compounds with a size mismatch between octahedral and tetrahedral sheets. Among them, synthetic Mg3Si2O5(OH)4 chrysotile nanoscrolls (obtained via the hydrothermal method) possess high thermal stability and mechanical properties, making them prospective composite materials fillers. However, accurate determination of these nano-objects with Young's modulus remains challenging. Here, we report on a study of the mechanical properties evolution of individual synthetic phyllosilicate nanoscrolls after a series of heat treatments, observed with an atomic force microscopy and calculated using the density functional theory. It appears that the Young's modulus, as well as shear deformation's contribution to the nanoscrolls mechanical behavior, can be controlled by heat treatment. The main reason for this is the heat-induced formation of covalent bonding between the adjacent layers, which complicate the shear deformation.

Dimensionality Mediated Highly Repeatable and Fast Transformation of Coordination Polymer Single Crystals for All-Optical Data Processing.

A family of coordination polymers (CPs) based on dynamic structural elements are of great fundamental and commercial interest addressing modern problems in controlled molecular separation, catalysis, and even data processing. Herein, the endurance and fast structural dynamics of such materials at ambient conditions are still a fundamental challenge. Here, we report on the design of a series of Cu-based CPs [Cu(bImB)Cl2] and [Cu(bImB)2Cl2] with flexible ligand bImB (1,4-bis(imidazol-1-yl)butane) packed into one- and two-dimensional (1D, 2D) structures demonstrating dimensionality mediated flexibility and reversible structural transformations. Using the laser pulses as a fast source of activation energy, we initiate CP heating followed by anisotropic thermal expansion and 0.2-0.8% volume changes with the record transformation rates from 2220 to 1640 s-1 for 1D and 2D CPs, respectively. The endurance over 103 cycles of structural transformations, achieved for the CPs at ambient conditions, allows demonstrating optical fiber integrated all-optical data processing.

Insights into Solid-To-Solid Transformation of MOF Amorphous Phases.

Metal-organic frameworks (MOFs) have been recently explored as crystalline solids for conversion into amorphous phases demonstrating non-specific mechanical, catalytic, and optical properties. The real-time control of such structural transformations and their outcomes still remain a challenge. Here, we use in situ high-resolution transmission electron microscopy with 0.01 s time resolution to explore non-thermal (electron induced) amorphization of a MOF single crystal, followed by transformation into an amorphous nanomaterial. By comparing a series of M-BTC (M: Fe3+, Co3+, Co2+, Ni2+, and Cu2+; BTC: 1,3,5-benzentricarboxylic acid), we demonstrate that the topology of a metal cluster of the parent MOFs determines the rate of formation and the chemistry of the resulting phases containing an intact ligand and metal or metal oxide nanoparticles. Confocal Raman and photoluminescence spectroscopies further confirm the integrity of the BTC ligand and coordination bond breaking, while high-resolution imaging with chemical and structural analysis over time allows for tracking the dynamics of solid-to-solid transformations. The revealed relationship between the initial and resulting structures and the stability of the obtained phase and its photoluminescence over time contribute to the design of new amorphous MOF-based optical nanomaterials.

Metal-Organic Frameworks in Modern Physics: Highlights and Perspectives.

Owing to the synergistic combination of a hybrid organic-inorganic nature and a chemically active porous structure, metal-organic frameworks have emerged as a new class of crystalline materials. The current trend in the chemical industry is to utilize such crystals as flexible hosting elements for applications as diverse as gas and energy storage, filtration, catalysis, and sensing. From the physical point of view, metal-organic frameworks are considered molecular crystals with hierarchical structures providing the structure-related physical properties crucial for future applications of energy transfer, data processing and storage, high-energy physics, and light manipulation. Here, the perspectives of metal-organic frameworks as a new family of functional materials in modern physics are discussed: from porous metals and superconductors, topological insulators, and classical and quantum memory elements, to optical superstructures, materials for particle physics, and even molecular scale mechanical metamaterials. Based on complementary properties of crystallinity, softness, organic-inorganic nature, and complex hierarchy, a description of how such artificial materials have extended their impact on applied physics to become the mainstream in material science is offered.

Correction: Laser printing of optically resonant hollow crystalline carbon nanostructures from 1D and 2D metal-organic frameworks.

Correction for 'Laser printing of optically resonant hollow crystalline carbon nanostructures from 1D and 2D metal-organic frameworks' by Leila R. Mingabudinova et al., Nanoscale, 2019, 11, 10155-10159.

Laser printing of optically resonant hollow crystalline carbon nanostructures from 1D and 2D metal-organic frameworks.

Using a hybrid approach involving a slow diffusion method to synthesize 1D and 2D MOFs followed by their treatment with femtosecond infrared laser radiation, we generated 100-600 nm well-defined hollow spheres and hemispheres of graphite. This ultra-fast technique extends the library of shapes of crystalline MOF derivatives appropriate for all-dielectric nanophotonics.

Cation Redistribution along the Spiral of Ni-Doped Phyllosilicate Nanoscrolls: Energy Modelling and STEM/EDS Study.

Here, we study the stress-induced self-organization of Mg2+ and Ni2+ cations in the crystal structure of multiwalled (Mg1-x ,Nix )3 Si2 O5 (OH)4 phyllosilicate nanoscrolls. The phyllosilicate layer strives to compensate size and surface energy difference between the metal oxide and silica sheets by curling. But as soon as the layer grows, the scrolling mechanism becomes a spent force. An energy model proposes secondary compensation of strain: two cations distribute along the nanoscroll spiral in accordance with preferable radii of curvature. To reveal this, we study synthetic (Mg1-x ,Nix )3 Si2 O5 (OH)4 nanoscrolls by the scanning transmission electron microscopy/energy-dispersive X-ray spectroscopy (STEM/EDS) technique. For a number of scrolls, we have found indeed a change of Ni concentration with increase in distance from the nanoscroll central axis. The concentration gradient, according to our estimates, can reach 50 at.% over 25 nm of the wall thickness.

The conformation of bovine serum albumin adsorbed to the surface of single all-dielectric nanoparticles following light-induced heating.

Interaction between nanoparticles and biomolecules leads to the formation of biocompatible or bioadverse complexes. Despite the rapid development of nanotechnologies for biology and medicine, relatively little is known about the structure of such complexes. Here, we report on the changes in conformation of a blood protein (bovine serum albumin) adsorbed on the surface of single all-dielectric nanoparticles (silicon and germanium) following light-induced heating to 640 K. This protein is considerably more resistant to heat when adsorbed on the nanoparticle than when in solution or in the solid state. Intriguingly, with germanium nanoparticles this heat resistance is more pronounced than with silicon. These observations will facilitate biocompatible usage of all-dielectric nanoparticles.

van der Waals Metal-Organic Framework as an Excitonic Material for Advanced Photonics.

Synergistic combination of organic and inorganic nature in van der Waals metal-organic frameworks supports different types of robust excitons that can be effectively and independently manipulated by light at room temperature, and opens new concepts for all-optical data processing and storage.