Creep Deformation of Mg-PSZ under Compressive Loading

Mg-PSZ(magnesia-partially-stabilized zirconia)has been studied under compressive loading at room temperature.Mechanical strain was recorded continuously using strain gauges while the sample phase composition and microstructure has been recorded at regular intervals on the ENGIN-X pulsed-neutron facility at the Rutherford-Appleton Laboratory in Didcot,England.Diffraction pattern analysis has been accomplished using the GSAS II software.The observed mechanical strain is time dependent,and a correlation is established between the mechanical creep strain and the phase and microstructural changes observed.Deformation and associated microstructural changes have been observed for all applied loads but were most marked for the highest load which was-1,200 MPa.It is suggested that the ongoing deformation and microstructural changes after unloading the specimen,are on account of a stress within the sample.

The role of strain in oxygen evolution reaction

The oxygen evolution reaction(OER)is a crucial step in metal-air batteries and water splitting technologies,playing a significant role in the efficiency and achievable heights of these two technologies.However,the OER is a four-step,four-electron reaction,and its slow kinetics result in high overpotentials,posing a challenge.To address this issue,numerous strategies involving modified catalysts have been proposed and proven to be highly efficient.In these strategies,the introduction of strain has been widely reported because it is generally believed to effectively regulate the electronic structure of metal sites and alter the adsorption energy of catalyst surfaces with reaction intermediates.However,strain has many other effects that are not well known,making it an important yet unexplored area.Based on this,this review provides a detailed introduction to the various roles of strain in OER.To better explain these roles,the review also presents the definition of strain and elucidates the potential mechanisms of strain in OER based on the d-band center theory and adsorption volcano plot.Additionally,the review showcases various ways of introducing strain in OER through examples reported in the latest literature,aiming to provide a comprehensive perspective for the development of strain engineering.Finally,the review analyzes the appropriate proportion of strain introduction,compares compressive and tensile strain,and examines the impact of strain on stability.And the review offers prospects for future research directions in this emerging field.

Exact solutions of two semi-infinite collinear cracks in piezoelectric strip

Using the complex variable function method and the conformal mapping technique,the fracture problem of two semi-infinite collinear cracks in a piezoelectric strip is studied under the anti-plane shear stress and the in-plane electric load on the partial crack surface.Analytic solutions of the field intensity factors and the mechanical strain energy release rate are derived under the assumption that the surfaces of the crack are electrically impermeable.The results can be reduced to the well-known solutions for a purely elastic material in the absence of an electric load.Moreover,when the distance between the two crack tips tends to infinity,analytic solutions of a semi-infinite crack in a piezoelectric strip can be obtained.Numerical examples are given to show the influence of the loaded crack length,the height of the strip,the distance between the two crack tips,and the applied mechanical/electric loads on the mechanical strain energy release rate.It is shown that the material is easier to fail when the distance between two crack tips becomes shorter,and the mechanical/electric loads have greater influence on the propagation of the left crack than those of the right one.

Structural self-reconstruction strategy empowering Ni-rich layered cathodes with low-strain for superior cyclabilities

The key to hindering the commercial application of Ni-rich layered cathode is its severe structural and interface degradation during the undesired phase transition(hexagonal to hexagonal(H2→H3)),degenerating from the build-up of mechanical strain and undesired parasitic reactions.Herein,a perovskite Li_(0.35)La_(0.55)TiO_(3)(LLTO)layer is built onto Ni-rich cathodes crystal to induce layered@spinel@perovskite heterostructure to solve the root cause of capacity fade.Intensive exploration based on structure characterizations,in situ X-ray diffraction techniques,and first-principles calculations demonstrate that such a unique heterostructure not only can improve the ability of the host structure to withstand the mechanical strain but also provides fast diffusion channels for lithium ions as well as provides a protective barrier against electrolyte corrosion.Impressively,the LLTO modified LiNi_(0.9)Co_(0.05)Mn_(0.05)O_(2)cathode manifests an unexpected cyclability with an extremely high-capacity retention of≈94.6%after 100 cycles,which is superior to the pristine LiNi_(0.9)Co_(0.05)Mn_(0.05)O_(2)(79.8%).Furthermore,this modified electrode also shows significantly enhanced cycling stability even withstanding a high cut-off voltage of 4.6 V.This surface self-reconstruction strategy provides deep insight into the structure/interface engineering to synergistically stabilize structure stability and regulate the physicochemical properties of Ni-rich cathodes,which will also unlock a new perspective of surface interface engineering for layered cathode materials.

Strain and illumination triggered regulations of up-conversion luminescence in Er-doped Bi_(0.5)Na_(0.5)TiO_(3)-BaTiO_(3)/Mica flexible multifunctional thin films

External stimuli induced effective regulations of luminescent material are of significant interest in the development of smart optical devices.Here,by simply doping with Er^(3+) in the 0.94Bi_(0.5)Na_(0.5)TiO_(3)-0.06BaTiO_(3)(BNTBT)ferroelectric host,using the bendable mica substrate,and exerting mechanical strain(bending)or light illumination(via photochromic reaction),the all-inorganic,highly-transparent and flexible Er-doped BNTBT/Mica luminescent-ferroelectric thin films were designed and fabricated,displaying strain-induced dramatically elevation of up-conversion photoluminescence(PL)intensity,suppression of PL concentration quenching,outstanding endurance and durability,convenient illuminationmediated PL quenching.And the strain-induced structural changes and local lattice distortions of the thin films were further explored through theoretical calculations and Raman measurement.Our results can supply the guidance of designing other luminescent-ferroelectric materials with controlled PL properties via easy mechanical/photo stimuli for expanding the application of multifunctional wearable memory devices.

Mechanical strain triggering flux jumps of multi-filamentary Nb_(3)Sn wires

The composite multi‐filamentary Nb_(3)Sn wire with a high critical current density is a preferred option for fabricating the superconducting magnet beyond the limit of NbTi wire(9–16 T).However,one crucial issue stems from the fact that electromagnetic force in superconducting coils is very strong,and the critical physical properties of Nb_(3)Sn,such as Jc,are more sensitive to mechanical strain than those of other possible low‐temperature superconductors.We theoretically investigated the impact of mechanical strain on the thermomagnetic instabilities such as the flux jump(FJ)and quenching of Nb_(3)Sn wire exposed to a static magnetic field and transport current.The good agreements with H formulation or H‐φformulation implemented on COMSOL software confirm the validity of our numerical simulations using home‐made codes.It is discovered that mechanical strain can trigger flux jumps even in a static magnetic field.Furthermore,the threshold value of mechanical strain to trigger the first flux jump is a monotonic function of the static magnetic field in the case of high transport currents,while it is a non‐monotonic function in the case of low transport currents.It is attributed to the fact that flux can be released by the mechanical strain,causing smooth flux penetration before triggering the flux jump.We also present the stable/unstable regions by applying mechanical strain by varying transport current,magnetic field,and working temperature,which helps in avoiding thermomagnetic instabilities while designing the superconducting magnet.