A5034019413- Iron-based superconductors research
- Magnetic and transport properties of perovskites and related materials
- Physics of Superconductivity and Magnetism
- Advanced Condensed Matter Physics
- Advancements in Battery Materials
- Additive Manufacturing Materials and Processes
- Advanced Battery Technologies Research
- Rare-earth and actinide compounds
- Nuclear Physics and Applications
- Electron and X-Ray Spectroscopy Techniques
- Welding Techniques and Residual Stresses
- Advanced Battery Materials and Technologies
- Additive Manufacturing and 3D Printing Technologies
- Magnetic properties of thin films
- Machine Learning in Materials Science
- Semiconductor materials and devices
- Ferroelectric and Negative Capacitance Devices
- Advanced X-ray and CT Imaging
- High Entropy Alloys Studies
- X-ray Diffraction in Crystallography
- MXene and MAX Phase Materials
- Corporate Taxation and Avoidance
- Electronic and Structural Properties of Oxides
- Chalcogenide Semiconductor Thin Films
- Laser Material Processing Techniques
SLAC National Accelerator Laboratory
2018-2025
Stanford Synchrotron Radiation Lightsource
2018-2025
Menlo School
2020-2021
Linac Coherent Light Source
2021
Brookhaven National Laboratory
2013-2019
Johns Hopkins University
2010-2014
Abstract Laser powder bed fusion additive manufacturing is an emerging 3D printing technique for the fabrication of advanced metal components. Widespread adoption it and similar technologies hampered by poor understanding laser-metal interactions under such extreme thermal regimes. Here, we elucidate mechanism pore formation liquid-solid interface dynamics during typical laser conditions using in situ X-ray imaging multi-physics simulations. Pores are revealed to form changes scan velocity...
In situ X-ray-based measurements of the laser powder bed fusion (LPBF) additive manufacturing process produce unique data for model validation and improved understanding. Synchrotron X-ray imaging diffraction provide high resolution, bulk sensitive information with sufficient sampling rates to probe melt pool dynamics as well phase microstructure evolution. Here, we describe a laboratory-scale LPBF test designed accommodate experiments at synchrotron source during operation. We also present...
Hydrothermal synthesis is challenging in metal oxide systems with diverse polymorphism, as reaction products are often sensitive to subtle variations parameters. This sensitivity rooted the non-equilibrium nature of low-temperature crystallization, where competition between different metastable phases can lead complex multistage crystallization pathways. Here, we propose an ab initio framework predict how particle size and solution composition influence polymorph stability during nucleation...
Significance Charge correlations have now been identified in the low-temperature phase of essentially all families underdoped cuprates, but two apparently distinct types. The first hosts locked charge and spin stripes which material La 1.875 Ba 0.125 CuO 4 (LBCO <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mn>1</mml:mn> <mml:mo>/</mml:mo> <mml:mn>8</mml:mn> </mml:mrow> </mml:math> ) is a paradigmatic example. In second type, density wave (CDW)...
Abstract Laser powder bed fusion (LPBF) is a method of additive manufacturing characterized by the rapid scanning high powered laser over thin metallic to create single layer, which may then be built upon form larger structures. Much melting, resolidification, and subsequent cooling take place at much higher rates with thermal gradients than in traditional metallurgical processes, this occurring below surface. We have used situ speed X-ray diffraction extract subsurface following...
Realization of extreme fast charging (XFC, ≤15 minutes) lithium-ion batteries is imperative for the widespread adoption electric vehicles.
Broad use of global or spatially averaging measurements over a cell to characterize highly localized Li plating phenomena in lithium-ion batteries during fast charging has created disconnect between and the underlying causes. Consequently, field is missing clear path implementing as well expand into extreme (XFC). Aiming bridge these gaps, we present detailed look local detection consequent cycle life implications for electrodes cells under XFC by utilizing electrochemistry high-energy X-ray...
Using soft and hard x-ray diffraction techniques, this group presents evidence of charge ordering in La${}_{1.88}$Sr${}_{0.12}$CuO${}_{4}$ that is rotated with respect to the Cu-O bond direction. In addition, importantly, authors show order suppressed below ${T}_{c}$.
Abstract As an emerging nonvolatile memory technology, HfO 2 ‐based ferroelectrics exhibit excellent compatibility with silicon CMOS process flows; however, the reliability of polarization switching in these materials remains a major challenge. During repeated field programming and erase state initially pristine ferroelectric capacitors, magnitude measured increases, phenomenon known as “wake‐up”. In this study, authors attempt to understand what causes wake‐up effect Hf 0.5 Zr O (HZO)...
We demonstrate a close relationship between superconductivity and the dimensions of Fe-Se(Te) tetrahedron in FeSe0.5Te0.5. This is done by exploiting thin film epitaxy, which provides controlled biaxial stress, both compressive tensile, to distort tetrahedron. The Se/Te height within found be crucial importance superconductivity, agreement with scenario that (π, π) spin fluctuations promote Fe superconductors.
Laser powder bed fusion (LPBF) metal additive manufacturing provides distinct advantages for aerospace and biomedical applications. However, widespread industrial adoption is limited by a lack of confidence in part properties driven an incomplete understanding how unique process parameters relate to defect formation ultimately mechanical properties. To address that gap, high‐speed X‐ray imaging used probe subsurface melt pool dynamics void‐formation mechanisms inaccessible other monitoring...
Unconventional superconductivity in the cuprates emerges from, or coexists with, other types of electronic order. However, these orders are sometimes invisible because their symmetry. For example, possible existence superfluid charge stripes normal state single layer cannot be validated with infrared optics, interlayer tunneling fluctuations vanish on average. Similarly, it is not easy to establish if responsible for dynamical decoupling superconducting layers over broad ranges doping and...
Low-temperature synthesis is crucial for advancing sustainable manufacturing and accessing novel metastable phases. Metal hydrides have shown great potential in facilitating the reduction of oxides at low temperatures, yet underlying mechanism─whether driven by H–, H2, or atomic H─remains unclear. In this study, we employ situ electrical transport measurements first-principles calculations to investigate CaH2-driven kinetics epitaxial α-Fe2O3 thin films. Intriguingly, samples direct contact...
Lithium-ion batteries are indispensable power sources for a wide range of modern electronic devices. However, battery lifespan remains critical limitation, directly affecting the sustainability and user experience. Conventional failure analysis in controlled lab settings may not capture complex interactions environmental factors encountered real-world, in-device operating conditions. This study analyzes commercial wireless earbud as model system within their intended usage context. Through...
In this work, we describe the instrumentation used to perform first operando transmission X-ray microscopy (TXM) and simultaneous diffraction of laser melting simulating powder bed fusion on XCS instrument at Linac Coherent Light Source (LCLS) free-electron (XFEL). Our TXM with 40× magnification in regime 11 keV gave spatial resolutions down 940 nm per line pair, effective pixel sizes 206 nm, image integration times <100 fs, frame rates tunable between 2.1 119 ns for two probe frames (0.48...
Using polarized and unpolarized neutron scattering we show that interstitial Fe in superconducting Fe_{1+y}Te_{1-x}Se_x induces a magnetic Friedel-like oscillation diffracts at Q_(in-plane)=(1/2,0) involves >50 neighboring sites. The >2 mu_B moment is surrounded by compensating ferromagnetic four spin clusters may seed double stripe ordering Fe_{1+y}Te. A semi-metallic 5-band model with (1/2,1/2) Fermi surface nesting fold symmetric super-exchange between two in-plane nearest neighbors...
Metal parts produced by laser powder bed fusion (LPBF) additive manufacturing exhibit characteristic microstructures comparable to those observed in welding. The primary cause of this microstructure is rapid, localized heating and cooling cycles, which result extreme thermal gradients where material solidification followed fast the solid state. final mechanical performance are also influenced pore formation caused melt pool fluid dynamics. Here, we use high speed, situ X-ray diffraction...
Although ultrafast manipulation of magnetism holds great promise for new physical phenomena and applications, targeting specific states is held back by our limited understanding how magnetic correlations evolve on timescales. Using resonant inelastic x-ray scattering we demonstrate that femtosecond laser pulses can excite transient magnons at large wavevectors in gapped antiferromagnets, they persist several picoseconds which opposite to what observed nearly gapless magnets. Our work...
The occurrence of charge-density-wave (CDW) order in underdoped cuprates is now well established, although the precise nature CDW and its relationship with superconductivity not. Theoretical proposals include contrasting ideas such as that pairing may be driven by fluctuations or static CDWs intertwine a spatially-modulated superconducting wave function. We test dynamics La$_{1.825}$Ba$_{0.125}$CuO$_4$ using x-ray photon correlation spectroscopy (XPCS) at vector, detected resonantly Cu...
A charge modulation has recently been reported in (Y,Nd)Ba${}_{2}$Cu${}_{3}$O${}_{6+x}$ [G. Ghiringhelli et al., Science 337, 821 (2012)]. Here we report Cu ${L}_{3}$ edge soft x-ray scattering studies comparing the lattice associated with YBa${}_{2}$Cu${}_{3}$O${}_{6.6}$ that well-known and spin stripe order La${}_{1.875}$Ba${}_{0.125}$CuO${}_{4}$. We find correlation length CuO${}_{2}$ plane is isotropic both cases, $259\ifmmode\pm\else\textpm\fi{}9$ \AA{} for...
A key step in the analysis of powder X-ray diffraction (PXRD) data is accurate determination unit-cell lattice parameters. This often requires significant human intervention and a bottleneck that hinders efforts towards automated analysis. work develops series one-dimensional convolutional neural networks (1D-CNNs) trained to provide parameter estimates for each crystal system. mean absolute percentage error approximately 10% achieved system, which corresponds 100- 1000-fold reduction search...