Bulk Strain Research Articles

Atomic-Scale View at the Segregation of Alkali Metals toward the KTaO3(001) Perovskite Surface.

Perovskites exhibit outstanding performance in applications such as photocatalysis, electrochemistry, or photovoltaics, yet their practical use is hindered by the instability of these materials under operating conditions, specifically caused by the segregation of alkali cations toward the surface. The problem arises from the bulk strain related to different cation sizes, as well as the inherent electrostatic instability of perovskite surfaces. Here, we focus on atomistic details of the surface-driven process of interlayer switching of alkali atoms at the inorganic perovskite surface. We show that the (001) surface of KTaO3 cleaved at room temperature contains equally populated TaO2 and KO terminations, while the uncompensated polarity of these terminations promotes diffusion of KO from the subsurface toward the topmost surface layer at temperatures as low as 200 °C. This effect is directly probed at the atomic scale by Atomic Force Microscopy and the chemical properties of the resulting surfaces are investigated by the adsorption of CO and H2O. The experiments indicate that KO segregation is associated with the formation of K and O vacancies in the near-surface region, which is further supported by depth-dependent X-ray Photoelectron Spectroscopy measurements and Density Functional Theory calculations. Our study shows that the KO segregation influences the surface reactivity both toward CO and water, which was probed at the atomic scale.

Effective Bulk Rheology of a Two‐Phase Subduction Shear Zone: Insights From Micromechanics‐Based Modeling and Implications for Subduction Interface Slow Slip Events

AbstractSubduction interfaces exhibit various slip styles, including slow slip events (SSEs). We use a micromechanics‐based approach to calculate the effective rheology of a shear zone containing ellipsoidal amphibolite clasts deforming by dislocation creep within an interconnected linear‐viscous phyllosilicate‐dominated matrix. Frictional failure occurs if local stress exceeds Mohr‐Coulomb yield strength. At moderate fluid overpressure, mixed‐frictional‐viscous behavior emerges at 350–560C, consistent with a broad zone of mixed fault slip behavior without requiring extreme fluid overpressures. Increasing stress in this transition zone promotes local frictional failure and raises bulk strain rate. If, however, the bulk strain rate increases by more than one order of magnitude, system‐wide frictional sliding becomes preferable. This strain rate increase is insufficient to explain the slip rates observed in geophysically detectable SSEs. Therefore, viscous matrix flow as modeled here cannot explain SSEs without either invoking dynamic weakening within a frictional‐viscous flow or a mechanism switch to dominantly frictional sliding.

Mechanical Impact of Heterogeneously Distributed H2O on Quartz Deformation

AbstractIn order to identify relations between mechanical behavior, deformation mechanisms, microstructural properties, and H2O distribution, Tana‐quartzite samples with added H2O ranging from 0 to 0.5 wt.% were deformed by axial shortening at constant displacement rates, at 900°C and 1 GPa, reaching up to ∼30% bulk strain. Samples with lower quantities of added H2O (0.1 and 0.2 wt.%) were in average ∼30 MPa weaker than the as‐is samples with no added H2O. In contrast, samples with more than 0.2 wt.% added H2O revealed more variable mechanical behavior, showing either weaker or stronger trend. The weaker samples showed strain localization in their central parts in the vicinity of the thermocouple, that is, the hottest parts of the samples, whereas the stronger samples showed localization in their upper, slightly colder parts. Bulk deformation is accommodated by crystal plasticity and dissolution‐precipitation processes. Distribution of H2O in our samples revealed systematic decrease of H2O content in the interiors of original grains, caused by increasing strain and H2O draining into grain boundary regions. With increasing content of added H2O, the quartz recrystallization gradually changes from subgrain‐rotation‐dominated to crack‐induced nucleation, along with increasing quantity of melt/fluid pockets. The unexpected strain localization in the upper parts of stronger samples most likely results from mode‐1‐cracking that led to drainage of grain boundaries (GB) due to the crack dilatancy effect, and inhibited dissolution‐precipitation in the hottest part of the samples next to the thermocouple. The locus of deformation is then shifted to colder regions where more H2O is available along GB.

Enhanced structural stability and durability in lithium-rich manganese-based oxide via surface double-coupling engineering

Lithium-rich manganese-based oxides (LRMOs) exhibit high theoretical energy densities, making them a prominent class of cathode materials for lithium-ion batteries. However, the performance of these layered cathodes often declines because of capacity fading during cycling. This decline is primarily attributed to anisotropic lattice strain and oxygen release from cathode surfaces. Given notable structural transformations, complex redox reactions, and detrimental interface side reactions in LRMOs, the development of a single modification approach that addresses bulk and surface issues is challenging. Therefore, this study introduces a surface double-coupling engineering strategy that mitigates bulk strain and reduces surface side reactions. The internal spinel-like phase coating layer, featuring three-dimensional (3D) lithium-ion diffusion channels, effectively blocks oxygen release from the cathode surface and mitigates lattice strain. In addition, the external Li3PO4 coating layer, noted for its superior corrosion resistance, enhances the interfacial lithium transport and inhibits the dissolution of surface transition metals. Notably, the spinel phase, as excellent interlayer, securely anchors Li3PO4 to the bulk lattice and suppresses oxygen release from lattices. Consequently, these modifications considerably boost structural stability and durability, achieving an impressive capacity retention of 83.4% and a minimal voltage decay of 1.49 mV per cycle after 150 cycles at 1 C. These findings provide crucial mechanistic insights into the role of surface modifications and guide the development of high-capacity cathodes with enhanced cyclability.

Investigation on coal permeability evolution considering the internal differential strain and its effects on CO2 sequestration capacity in deep coal seams

The gas adsorption/desorption-induced coal deformation effect is a significant factor governing the evolution of coalbed permeability. Current theoretical investigations typically coal bulk and fracture deformation induced by gas are equivalent, neglecting the matrix-fracture interactions. Based on internal adsorption stress, this paper proposes Internal Differential Strain Coefficient (IDSC) to quantitatively characterize the relationship between coal bulk and fracture strain under equilibrium conditions. Coupling this coefficient constructs a binary gas permeability evolution model considering matrix-fracture interactions. Through numerical simulations of CO2-ECBM processes under various internal differential strain circumstances using this model, dynamic evolution patterns of diverse parameters are obtained. The research findings indicate that along the direction of CO2 injection, matrix-fracture interactions exhibit a complex trend of initially increasing, then decreasing and then increasing, and the increase in internal differential strain levels results in a downward trend in permeability peak. Additionally, the evolutionary characteristics of CH4 recovery and cumulative CO2 storage rising with increasing internal differential strain levels were obtained on time scales using a fixed-point monitoring methodology. Inspired by the aforementioned laws, this paper discusses the macroscopic influence of burial depth on the effects of internal differential strain, providing new theoretical support for CO2 sequestration injection methods in deep coal seams.

Study of the static mechanical properties of tailings under the influence of multiple lens types

There are many types of lenses in tailings ponds that have important influences on stability. Lens types of more than 150 tailings dams were analyzed in China’s severely cold regions, cold regions, hot summers and cold winters (the civil building thermal design code (GB50176-2016)). The mechanism of lens formation is discussed in this paper. Triaxial tests of tailings were carried out with fine mud tailing lenses, notched lenses, ice lenses and soft plastic soil lenses. Moreover, a three-dimensional triaxial test model with a flexible boundary is constructed to study the influence of different lenses on the mechanical properties of the tailings. The lens can change the failure mode of the tailings. These faults can change the dilatancy failure of tailings to failure along the “lens-tailings” interface. With increasing confining pressure, the ability of the lens to weaken the strength of the tailings increases. At 500 kPa, the strengths of the samples with fine mud tailing lenses, notched lenses, ice lenses and soft plastic soil lenses are 95.28%, 88.79%, 76.99% and 5.49%, respectively, of those of the sample without lenses. In addition to soft plastic soil lenses, other lenses provide space to accommodate the deformation of tailings, thereby reducing the bulk strain of tailings. The conclusions of this study can provide theoretical support for studying the failure mode of tailings dams under the influence of lenses and improving the local stability of tailings ponds.

Transtension, brittle-ductile shear zones and hydrothermal ore deposits: Towards quantitative structural and kinematic models

Transtension is a fundamental process for the development of hydrothermal ore deposits, since it allows the required extension and dilatancy for hydrothermal fluid circulation and resulting ore mineralization. Transtension operates at multiple scales and, therefore, is not only relevant for deposits linked with extensional tectonics but also for those related to contraction/transpression. In this context, brittle-ductile shear zones represent a first-order metallotect that control the emplacement of mineralization. The distribution of ore minerals is largely influenced by bulk strain, kinematics and strain fabrics of these mineralized structures. The modified strain triangle is proposed as a simple tool to characterize strain conditions of transtension-related ore deposits associated with brittle-ductile shear zones, providing valuable information for metallogenetic models. In addition, a structural classification of ore deposits is proposed, based on the discussion of key deposit types and case studies. The main advantage of this approach is that it mainly relies on quantitative structural data and, therefore, is extremely useful for exploration. Furthermore, this classification avoids a priori assumptions on the tectonic setting, which can subsequently be inferred based on further regional evidence.

Strain-Prompted Giant Flexo-Photovoltaic Effect in Two-Dimensional Violet Phosphorene Nanosheets.

As a second-order nonlinear optical phenomenon, the bulk photovoltaic (BPV) effect is expected to break through the Shockley-Queisser limit of thermodynamic photoelectron conversion and improve the energy conversion efficiency of photovoltaic cells. Here, we have successfully induced a strong flexo-photovoltaic (FPV) effect, a form of BPV effect, in strained violet phosphorene nanosheets (VPNS) by utilizing strain engineering at the h-BN nanoedge, which was first observed in nontransition metal dichalcogenide (TMD) systems. This BPV effect was found to originate from the disruption of inversion symmetry induced by uniaxial strain applied to VPNS at the h-BN nanoedge. We have revealed the intricate relationship between the bulk photovoltaic effect and strain gradients in VPNS through thickness-dependent photovoltaic response experiments. A bulk photovoltaic coefficient of up to 1.3 × 10-3 V-1 and a polarization extinction ratio of 21.6 have been achieved by systematically optimizing the height of the h-BN nanoedge and the thickness of VPNS, surpassing those of reported TMD materials (typically less than 3). Our results have revealed the fundamental relationship between the FPV effect and the strain gradients in low-dimensional materials and inspired further exploration of optoelectronic phenomena in strain-gradient engineered materials.

Continuum-molecular modeling of planar micropolar media: Anisotropy, chiral properties and length-scale effects

This paper presents a continuum-molecular formulation for bi-dimensional micropolar media within the mathematical formalism of a revised peridynamic theory with oriented material points. A variational procedure is considered to derive the fundamental governing equations of the model, which postulates that material points interact through pair potentials allowing generalized pairwise actions to be derived as energy conjugates to properly defined pairwise deformation measures. While continuity of mass is assumed, constitutive laws are produced for long-range micro-interactions to reproduce the effective behavior of the material at the macro-scale. The definition of proper micromoduli functions respecting material symmetries and invariance properties allows then to obtain a non-local micropolar continuum based on pseudo-discrete kinematics, while providing a mechanism-based description of material anisotropy and coupling behaviors uncovered by classical elasticity. An analytic micro-macro moduli correspondence procedure is also established, based on the formal analogy with the constitutive tensor of centrosymmetric planar micropolar continua. As an important result of this research, we show that distinctive chiral effects of micropolar elasticity can be reproduced by introducing a directional independent pseudo-scalar pair potential, which turns out to be analytically vanishing when the rotationally invariant part of the corresponding continuum elastic tensor is invariant to mirror reflections as well. Moreover, the proposed formulation demonstrates sensitivity to elastic bending size-effect as specific property of structured materials homogenized as micropolar continua, and related to the characteristic length of their underlying microstructure. The resulting constitutive non-locality, which plays an important role in fracture problems, is conceptually separated with respect to the intrinsic non-local character of the model related to the integral nature of its governing equations, and then does not vanish when the horizon reduces to zero. The theoretical findings and the effectiveness of the model are successfully verified through illustrative examples referred to representative cases of structured materials homogenized as micropolar continua, including length-scale dependent quasi-static crack propagation as well as the mechanism-based description of the coupling between bulk strain and micro-rotation in elastic bi-dimensional homogenized chiral lattices.

Crucial role of water-present melting in metagranite: Implications for the instigation of crustal-scale shear zones

Abstract Where, when, and why large-scale shear zones nucleate and propagate into the continental lithosphere are critical issues that challenge the research in tectonics. The East Variscan shear zone is one of the crustal-scale strike-slip faults that shaped the Variscan orogenic crust during late Carboniferous time. Field-based structural analysis and petrological observations demonstrate that suprasolidus high-strain deformation zones and metagranite occurrences are spatially correlated. Among the three dominant lithologies forming this orogenic middle crust (metapelite, metagraywacke, and metagranite), petrological observations and phase equilibrium modeling indicate that the latter is the first lithology that melts during collision-induced heating, in response to H2O-fluid-saturated melting. Our field data and modeling suggest that the water-fluxed melting of metagranite has a primary rheological control on the localization, instigation, and growth of crustal-scale shear zones in the middle crust. Thus, the distribution and geometry of metagranite at the crustal scale could be regarded as critical parameters influencing the rheological inheritance governing the tectonic evolution and localization of bulk strain in the continental lithosphere.

Probing electronic, magnetic and thermal properties of NiMnSb Half-Heusler alloy for spintronics as an environmentally friendly energy resource: A DFT+U and Monte Carlo study

The NiMnSb Half-Heusler alloy has a high Curie temperature (Tc = 720 K) and high spin polarization (P = 100%), which makes it one of the good magnetic materials with exceptional structural, electrical, magnetic, and thermo-elastic properties. Using Density Functional Theory with Hubbard correction and Monte Carlo methods, we have probed the electronic, magnetic and thermal properties of NiMnSb. The computational study found a lattice parameter of 5.91Å and an integer value of total moment magnetic equal to 4μB using GGA method. However, using the Hubbard correction, these values increased by 0.17% and 9.25% to the experimental results, respectively, which also resulted in the destruction of the Half-metallic behavior. The high total magnetic moment is preserved despite bulk and axial strain by varying the relative change of lattice parameter and c/a ratio. The variation of spin polarization against the change of lattice parameter to experimental value reveals a very strong spin polarization between -2.2% and 0.2%. The thermal properties show that the alloy under probing is more stable, both thermodynamically and thermo-mechanically. The Monte Carlo simulation shows that NiMnSb’s strong ferromagnetic property stays its high as the temperature rises to 720 K. Above 720 K, NiMnSb joins the group of paramagnetic materials.

Interpebble, Intrapebble and Bulk Strain Estimation in Laitsopliah and Nongbri Conglomerate of Shillong Basin of Meghalaya, NE India

In the present work quantitative strain analysis of Nongbri and Laitsopliah conglomerates of the Mesoproterozoic Shillong basin of the Shillong plateau is carried out considering the stretched pebble as strain markers. Six different techniques for intrapebble, interpebble and bulk rock strain estimation are applied, results are compared systematically and all suggest broadly flattening type of deformation (0<k< 1) for Laitsopliah conglomerate pointing to S- tectonites and constrictional type (1<k <∞) of deformation for Nongbri conglomerate pointing to L-tectonites. Keywords: Strain, Conglomerate, Pebbles, Shillong Plateau

(Invited) Achieving Stable Black-CsPbI3 Thin-Films for Opto-Electronic Applications

Halide perovskite materials, particularly CsPbI3, have emerged as promising candidates for optoelectronic applications, including solar cells, due to their favorable bandgap of ~1.7 eV for tandem solar cells with silicon-based counterparts. However, their widespread adoption is hindered by their instability and reactivity under ambient conditions, especially to moisture and oxygen. The black phase CsPbI3 polymorphs (α, β, and γ) are only stable at elevated temperatures, and at room temperature (RT), they transform to a yellow, nonperovskite phase (δ) with a wider bandgap of ~2.8 eV, leading to a loss of device performance. To address this challenge, various approaches have been explored to increase the stability of the black phase of CsPbI3 thin films under ambient conditions.[1]One approach is based on interface engineering to induce crystal strain, which increases the stabilization time of the black phase. Thin films of CsPbI3 are prepared on substrates with different thermal expansion coefficients, leading to interfacial strain when quenched from high temperatures (> 320 °C) to RT. This interfacial strain increases the stability of the black phase from a few seconds in bulk polycrystalline samples to a few minutes in thin films, as shown in Fig. 1(a).[2] Additionally, black phase stabilization has been enhanced to a few hours by introducing minimal amounts (< 5%) of dopant elements in the Pb site of CsPbI3, which modifies the texture and generates microstrain in the polycrystalline perovskite films (see Fig. 1(b)).[3] The dopants locally disrupt the normal bonding arrangement and manipulate strains/distortions, and structural relaxation around the dopants is mediated by dynamic disorder and the relatively soft elastic constants of halide perovskite, resulting in the stabilization of the required crystallographic phase.Furthermore, annealing of CsPbI3 thin films in the presence of oxygen has been explored as another approach to increase the stability of the black phase (stable for a few days). Heating the films under oxygen leads to surface oxidation and the formation of Pb-O bonds, resulting in the gathering of Pb and O atoms and the formation of lead oxide. The replacement of I atoms in the inorganic frameworks by O atoms tends to form volatile iodine (I2), but PbI2 is typically detected as the dominant product of degradation during heating in a dry air environment (Fig. 1(c)).[4] The oxidation products on the surface could potentially serve as a protective layer to inhibit further oxidation.Another highly effective approach to enhance the stability of the black phase CsPbI3 in perovskite thin films and devices is through the implementation of coarse photolithography to embed a PbI2-based interfacial microstructure.[5] The resulting films, adorned with a tessellating microgrid ((Fig. 1(d))), display remarkable resistance to moisture-induced decay and demonstrate prolonged stability of the black phase, persisting beyond 2.5 years even in dry environments. This remarkable stability can be attributed to the significant increase in the phase transition energy barrier and the effective limitation of potential yellow phase formation to structurally isolated domains within the microgrid.In summary, our laboratory has effectively implemented various methods to enhance the durability of black phase CsPbI3 thin films when exposed to ambient conditions. These methods comprise inducing interfacial strain, introducing bulk strain through doping, embedding interfacial microstructures, and surface oxidation. These techniques have demonstrated encouraging outcomes in maintaining the black phase of CsPbI3 for extended durations, ranging from a few minutes to several months, and exhibit significant potential for the advancement of practical applications of CsPbI3-based perovskite solar cells. Further exploration and advancement in this direction are anticipated to contribute to achieving long-lasting and efficient perovskite devices.[1] Acc. Mater. Res., 2020, 1, 1, 3–15[2] Science, 2019, 365, 679-684[3] J. Am. Chem. Soc., 2021, 143, 28, 10500–10508[4] unpublished results[5] Nature Commun., 2022, 13, 7513. Figure 1

Unraveling the synergistic effects of Cu-Ag tandem catalysts during electrochemical CO2 reduction using nanofocused X-ray probes

Controlling the selectivity of the electrocatalytic reduction of carbon dioxide into value-added chemicals continues to be a major challenge. Bulk and surface lattice strain in nanostructured electrocatalysts affect catalytic activity and selectivity. Here, we unravel the complex dynamics of synergistic lattice strain and stability effects of Cu-Ag tandem catalysts through a previously unexplored combination of in situ nanofocused X-ray absorption spectroscopy and Bragg coherent diffraction imaging. Three-dimensional strain maps reveal the lattice dynamics inside individual nanoparticles as a function of applied potential and product yields. Dynamic relations between strain, redox state, catalytic activity and selectivity are derived. Moderate Ag contents effectively reduce the competing evolution of H2 and, concomitantly, lead to an enhanced corrosion stability. Findings from this study evidence the power of advanced nanofocused spectroscopy techniques to provide new insights into the chemistry and structure of nanostructured catalysts.

Suppressing Bulk Strain and Surface O2 Release in Li-Rich Cathodes by Just Tuning the Li Content.

Layered oxides represent a prominent class of cathodes employed in lithium-ion batteries. The structural degradation of layered cathodes causes capacity decay during cycling, which is generally induced by anisotropic lattice strain in the bulk of cathode particle and oxygen release at the surface. However, particularly in lithium-rich layered oxides (LLOs) that undergo intense oxygen redox reactions, the challenge of simultaneously addressing bulk and surface issues through a singular modification technique remains arduous. Here a thin (1-nm) and coherent spinel-like phase is constructed on the surface of LLOs particle to suppress bulk strain and surface O2 release by just adjusting the amount of lithium source during synthesis. The spinel-like phase hinders the surface O2 release by accommodating O2 inside the surface layer, while the trapped O2 in the bulk impedes strain evolution by ≈70% at high voltages compared with unmodified LLOs. Consequently, the enhanced structural stability leads to an improved capacity retention of 97.6% and a high Coulombic efficiency of ≈99.5% after 100 cycles at 0.1°C. These findings provide profound mechanistic insights into the functioning of surface structure and offer guidance for synthesizing high-capacity cathodes with superior cyclability.

Large Perpendicular Magnetic Anisotropy Induced by an Intersite Charge Transfer in Strained EuVO2H Films.

Perovskite oxides ABO3 continue to be a major focus in materials science. Of particular interest is the interplay between A and B cations as exemplified by intersite charge transfer (ICT), which causes novel phenomena including negative thermal expansion and metal-insulator transition. However, the ICT properties were achieved and optimized by cationic substitution or ordering. Here we demonstrate an anionic approach to induce ICT using an oxyhydride perovskite, EuVO2H, which has alternating layers of EuH and VO2. A bulk EuVO2H behaves as a ferromagnetic insulator with a relatively high transition temperature (TC) of 10 K. However, the application of external pressure to the EuIIVIIIO2H bulk or compressive strain from the substrate in the thin films induces ICT from the EuIIH layer to the VIIIO2 layer due to the extended empty V dxy orbital. The ICT phenomenon causes the VO2 layer to become conductive, leading to an increase in TC that is dependent on the number of carriers in the dxy orbitals (up to a factor of 4 for 10 nm thin films). In addition, a large perpendicular magnetic anisotropy appears with the ICT for the films of <100 nm, which is unprecedented in materials with orbital-free Eu2+, opening new perspectives for applications. The present results provide opportunities for the acquisition of novel functions by alternating transition metal/rare earth layers with heteroanions.

DFT+U investigations and Monte Carlo simulations on the structural, mechanical, electronic and magnetic properties of the half-Heusler alloy CoMnSe for spintronics applications

We report the structural stability and half-metallicity of the half-Heusler alloy CoMnSe via the density functional theory (DFT). The γ-phase ferromagnetic of CoMnSe is more energetically stable than other phases. The electronic and magnetic properties show that the CoMnSe is a false half-metal ferromagnetic with 98.10% spin polarization and a total magnetic moment of 4μB. This value is in good agreement with the Slater-Pauling rule and available data using the GGA method, whereas the GGA+U method shows it is a ferrimagnetic metal with 95.73% spin polarization, and the total magnetic moment is 4.01μB. The effects of Bulk strain and axial strain demonstrate that the relative change of total magnetic moment Mtot and spin polarization P of CoMnSe is almost negligible, indicating that the half-metallicity is strong against Bulk strain and axial strain. Using Monte Carlo simulations, a transition ferromagnetic-paramagnetic response is also studied.

Metal identity effects in the fracture behavior of coordinatively crosslinked elastomers

Polymers comprising polybutadiene backbones with 2,6-bis(1′-methyl-benzimidazolyl)pyridine (MeBip) sidechains were crosslinked by complexation with two different metal salts, either with copper(II) trifluoromethanosulfonate or with iron(II) trifluoromethanosulfonate. Dynamic mechanical analysis (DMA) and small-angle X-ray scattering (SAXS) data indicate that the crosslinking density and topology of the two materials are the same. The material crosslinked with copper ions, however, exhibits a higher extensibility and fracture energy than the polymer crosslinked with iron. These differences are attributed to differing mechanochemical responses of the metal complexes to applied stress. Computational results further indicate that the copper complexes are more labile, both in the stress-free state as well as upon application of force, and that the “open” complex in which only one MeBip ligand coordinates copper binds fewer counter-ions than the iron-coordinated analog. Both these factors enable easier re-binding of a second MeBip ligand. The computations further suggest that mechanochemically coupled spin-crossover behavior must be considered to fully understand the response of these metal-ligand complexes to mechanical stimuli. The data presented here furthers the facile manipulation of a material's strain response via metal species modulation, and the results offer a way to understand the relationship between bulk and molecular strain response.

Selective inversion of rift basins in lithospheric-scale analogue experiments

Abstract. Basin inversion is commonly attributed to the reverse reactivation of basin-bounding normal faults. This association implies that basin uplift and inversion-related structures are mainly controlled by the frictional behaviour of pre-existing faults and associated damage zones. In this study, we use lithospheric-scale analogue experiments of orthogonal extension followed by shortening to explore how the flow behaviour of ductile layers underneath rift basins promote or suppress basin inversion. Our experiments show that the rheology of the ductile lower crust and lithospheric mantle, modulated by the imposed bulk strain rate, determine (1) basin distribution in a wide rift setting and (2) strain accommodation by fault reactivation and basin uplift during subsequent shortening. When the ductile layers deform uniformly during extension (i.e. stretching) and shortening (i.e. thickening), all of the basins are inverted. When deformation in the ductile layers is localised during extension (i.e. necking) and shortening (i.e. folding), only some basins – which are evenly spaced apart – are inverted. We interpret the latter as selective basin inversion, which may be related to the superposition of crustal-scale and lithospheric-scale boudinage during the previous basin-forming extensional phase and/or folding of the ductile layers during shortening.

(Keynote) Modeling Battery Performance Due to Volume Change in Porous Electrodes Towards the Development of Electrified Propulsion Systems

In order to accurately predict the behavior of electrochemical devices, it is necessary to develop sophisticated models that take into consideration transport processes, electrochemical phenomena, mechanical stresses, and structural deformations on the operation of an electrochemical system. Several different models exist that can predict the electrochemical performance of these devices under a variety of operating and design conditions. However, in many of these models, the porosity of a porous electrode is often assumed to be constant since the volume changes seen during the intercalation reaction can be small. However, electrode materials developed in recent years show significant volume changes during intercalation, which are unable to be accurately predicted using these constant porosity models.Porosity and dimensional changes in an electrode can significantly affect the resistance of the battery during cycling and can cause premature failure of the battery due to generated stresses. Over the past decade and a half, we have shown the ability to incorporate dimensional and porosity changes in a porous electrode during intercalation through the coupling of various mechanics treatments with porous electrode theory. Many assumptions were used to obtain an analytical solution, including the assumption of bulk strain, uniform porosity, and uniform concentration across the electrode.[1-4] This model was extended to look at design considerations as well as non-uniformity within a single porous electrode coupled to a lithium metal reference.[5] This model was further improved by removing some of the earlier assumptions and is capable of illustrating the development of stress, strain gradients, and porosity gradients across a porous electrode during cycling in a battery containing a blended anode undergoing volume change coupled to an NMC cathode.[6] The reversible volume change predictions were then validated using data from pouch cells seen in the Chevrolet Volt.[7] Following our validation studies, we illustrated the impact that coupled electrochemical-mechanical volume change can have on electric vehicle battery pack design.[8] References P. M. Gomadam and J. W. Weidner, J Electrochem Soc, 153, A179 (2006).T. R. Garrick, K. Kanneganti, X. Y. Huang and J. W. Weidner, J Electrochem Soc, 161, E3297 (2014).T. R. Garrick, Y. Dai, K. Higa, V. Srinivasan and J. W. Weidner, Ecs Transactions, 72, 11 (2016).T. R. Garrick, X. Huang, V. Srinivasan and J. W. Weidner, J Electrochem Soc, 164, E3552 (2017).T. R. Garrick, K. Higa, S.-L. Wu, Y. Dai, X. Huang, V. Srinivasan and J. W. Weidner, J Electrochem Soc, 164, E3592 (2017).D. J. Pereira, J. W. Weidner and T. R. Garrick, J Electrochem Soc, 166, A1251 (2019).D. J. Pereira, M. A. Fernandez, K. C. Streng, X. X. Hou, X. Gao, J. W. Weidner and T. R. Garrick, J Electrochem Soc, 167, 080515 (2020).D. J. Pereira, A. M. Aleman, J. W. Weidner and T. R. Garrick, J Electrochem Soc, 169, 020577 (2022).