First In Situ Lattice Strains Measurements Under Load at VULCAN

An, Ke; Skorpenske, Harley D.; Stoica, A. D.; Ma, Dong; Wang, Xun-Li; Cakmak, Ercan

doi:10.1007/s11661-010-0495-9

Cited by 213 publications

(125 citation statements)

References 13 publications

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“…The time of fi ght powder neutron diffraction data were collected on the VULCAN beamline at the Spallation Neutron Sources (SNS) in the Oak Ridge National Laboratory. [ 22 ] An incident beam (5 mm × 12 mm) of 0.7 to 3.5 Å bandwidth allowing 0.5≈2.5 Å d-space in diffracted patterns in the ±90° 2 θ detector banks was selected using the double-disk choppers at 30 Hz speed. High intensity mode was employed with Δ d / d ≈ 0.45%.…”

Section: Methodsmentioning

confidence: 99%

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Operando Lithium Dynamics in the Li‐Rich Layered Oxide Cathode Material via Neutron Diffraction

Liu

Chen

et al. 2016

Advanced Energy Materials

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106

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in battery technology have come since its fi rst demonstration, the high energy demands needed to electrify the automotive industry have not yet been met with the current technology. [ 2,3 ] One considerable bottleneck is the cathode energy density. [ 2,3 ] The lithium layered oxides utilize transition metal redox pairs for charge/ discharge compensation during lithium extraction and intercalation offering a theoretical capacity of 270 mAh g −1 for complete lithium extraction. [ 3,4 ] However, practical capacities have so far shown to be ≈200 mAh g −1 due to degradation reactions and large lattice contractions at low lithium content, limiting its capability to meet future demands. One possible cathode material is the Li-rich layered oxide compounds x Li 2 MnO 3 ⋅(1 − x )LiMO 2 (M = Ni, Mn, Co) (0.5 = < x = <1.0) that exhibit capacities over 280 mAh g −1 obtainable by the combination of the typical transition metal redox pair with the additional oxygen redox reaction as the charge compensation mechanism. [ 5 ] In this class of compounds, lithium ions can reside in both lithium layer and transition metal layer of close packed oxygen framework, typical from O3 type layered oxides like LiCoO 2 . Large irreversible capacities are often observed in these materials due to irreversible oxygen loss or side reactions stemming for the electrolyte. [ 6 ] It has been also observed using ex situ NMR (nuclear magnetic resonance) that lithium reinsertion back into the transition metal layer is little to none. [ 7 ] Several different lithium extraction/insertion sites and migration pathways are available, where lithium may be extracted from lithium or transition metal layers and lithium from octahedral coordinated sites to tetrahedral sites to form Li-Li dumbbells. [ 8 ] However, these studies have not revealed the dynamic process of lithium migration for the Li-rich material under operando electrochemical cycling conditions. Neutron scattering has several distinct advantages for battery studies: (1) The sensitivity of neutron to light elements such as lithium and oxygen is signifi cant in order to determine their position in the crystal structure; (2) Compares to the X-ray, the neutron shows larger scattering contrast between neighboring elements in the periodic table specifi cally the scattering lengths, e.g., for transition metals in this case: Ni, 10.3 fm; Mn, −3.73 fm; Co, 2.49 fm; and (3) The deep penetration capability of neutron allows simultaneous observation of the cathode and

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Section: Methodsmentioning

confidence: 99%

“…The SNS power was at nominal 1100 KW. [ 22 ] Time stamped neutron event data were collected while the cells were under continuous cycling. Neutron diffraction data were sliced and reduced by the VDRIVE software.…”

Section: Methodsmentioning

confidence: 99%

Operando Lithium Dynamics in the Li‐Rich Layered Oxide Cathode Material via Neutron Diffraction

Liu

Chen

et al. 2016

Advanced Energy Materials

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106

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“…The in situ neutron diffraction measurements were performed at the VULCAN Engineering Materials Diffractometer [56][57][58], the Spallation Neutron Source (SNS), Oak Ridge National Laboratory (ORNL) during fully reversed low-cycle fatigue under a continuous-loading condition. Due to the high neutron flux at the VULCAN instrument at SNS, the real-time in situ neutron diffraction measurements have been successfully employed in a number of studies [20,54,[59][60][61][62].…”

Section: Real-time In Situ Neutron Diffraction Measurementsmentioning

confidence: 99%

Unraveling cyclic deformation mechanisms of a rolled magnesium alloy using in situ neutron diffraction

Liaw

2015

Acta Materialia

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In the current study, the deformation mechanisms of a rolled magnesium alloy were investigated under cyclic loading using real-time in situ neutron diffraction under a continuous-loading condition. The relationship between the macroscopic cyclic deformation behavior and the microscopic response at the grain level was established. The neutron diffraction results indicate that more and more grains are involved in the twinning and detwinning deformation process with the increase of fatigue cycles. The residual twins appear in the early fatigue life, which is responsible for the cyclic hardening behavior. The asymmetric shape of the hysteresis loop is attributed to the early exhaustion of the detwinning process during compression, which leads to the activation of dislocation slips and rapid strain-hardening. The critical resolved shear stress for the activation of tensile twinning closely depends on the residual strain developed during cyclic loading. In the cycle before the sample fractured, the dislocation slips became active in tension, although the sample was not fully twinned. The increased dislocation density leads to the rise of the stress concentration at weak spots, which is believed to be the main reason for the fatigue failure. The deformation history greatly influences the deformation mechanisms of hexagonal-close-packed-structured magnesium alloy during cyclic loading.

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“…) while collecting data continuously (An et al [7] ; Wang et al [8] ; Wu et al [9] ). It is clear that this new approach avoids the influence of the interrupts on lattice strain measurement.…”

mentioning

confidence: 99%

Study of Lattice Strain Evolution in Stainless Steel Under Tension: The Role of Self‐Consistent Plasticity Model

Guo

Wang

et al. 2015

steel research int.

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The recently developed large strain elastic visco-plastic self-consistent (EVPSC) model, with various popular self-consistent schemes including the Affine, Meff, Secant, and Tangent, is used to study the lattice strain evolution in a stainless steel under uniaxial tension. The material parameters for the various self-consistent schemes are fitted to experimental stress and strain curve under uniaxial tension. An assessment of the predictive capability of the self-consistent schemes is performed based on comparisons of the predicted lattice strain evolutions and in situ neutron diffraction measurements done on the same material. It is found that, among the self-consistent schemes examined, the self-consistent schemes with grain interaction stiffness halfway between those of the limiting Secant (stiff) and Tangent (compliant) approximations give the best results.

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First In Situ Lattice Strains Measurements Under Load at VULCAN

Cited by 213 publications

References 13 publications

Operando Lithium Dynamics in the Li‐Rich Layered Oxide Cathode Material via Neutron Diffraction

Operando Lithium Dynamics in the Li‐Rich Layered Oxide Cathode Material via Neutron Diffraction

Unraveling cyclic deformation mechanisms of a rolled magnesium alloy using in situ neutron diffraction

Study of Lattice Strain Evolution in Stainless Steel Under Tension: The Role of Self‐Consistent Plasticity Model

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