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At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Antigen‐binding fragments with improved crystal lattice packing and enhanced conformational flexibility at the elbow region as crystallization chaperones

It has been shown previously that a set of three modifications—termed S1, Crystal Kappa, and elbow—act synergistically to improve the crystallizability of an antigen-binding fragment (Fab) framework. Here, we prepared a phage-displayed library and performed crystallization screenings to identify additional substitutions—located near the heavy-chain elbow region—which cooperate with the S1, Crystal Kappa, and elbow modifications to increase expression and improve crystallizability of the Fab framework even further. One substitution (K141Q) supports the signature Crystal Kappa-mediated Fab:Fab crystal lattice packing interaction. Another substitution (E172G) improves the compatibility of the elbow modification with the Fab framework by alleviating some of the strain incurred by the shortened and bulkier elbow linker region. A third substitution (F170W) generates a split-Fab conformation, resulting in a powerful crystal lattice packing interaction comprising the biological interaction interface between the variable heavy and light chain domains. In sum, we have used K141Q, E172G, and F170W substitutions—which complement the S1, Crystal Kappa, and elbow modifications—to generate a set of highly crystallizable Fab frameworks that can be used as chaperones to enable facile elucidation of Fab:antigen complex structures by x-ray crystallography.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Magnetic ground states of honeycomb lattice Wigner crystals

Lattice Wigner crystal states stabilized by long-range Coulomb interactions have recently been realized in two-dimensional moiré materials. We employ large-scale unrestricted Hartree-Fock techniques to unveil the magnetic phase diagrams of honeycomb lattice Wigner crystals. For the three lattice filling factors with the largest charge gaps, $n=2/3,1/2,1/3$, the magnetic phase diagrams contain multiple phases, including ones with non-collinear and non-coplanar spin arrangements. We discuss magnetization evolution with external magnetic field, which has potential as an experimental signature of exotic spin states. Our theoretical results could potentially be validated in moiré materials formed from group VI transition metal dichalcogenide twisted homobilayers.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Dislocation‐Driven Formation of Oriented Macroperiodic Metastructures of Curved Single Crystal Lattices in Glass

Abstract Single crystals fabricated in glass by localized heating can develop uniquely deformed lattices stabilized by the surrounding amorphous medium. The development of lattice curvature appears to be intrinsic to the crystal growth process in some systems, while the result of the locally changing crystallography in others. In this work, a model laser‐fabricated rotating lattice Sb 2 S 3 crystal grown in stoichiometric glass is used to demonstrate fabrication of novel macroperiodic metastructures that utilize intrinsic lattice curvature superimposed with subtle crystallographic influences. The limited availability of slip systems drives the lattice curvature magnitude to vary with crystal growth direction, maximizing for lattices aligned with the predominant Burgers vector along with corresponding increases in dislocation density. Misaligned lattice orientations form smaller secondary lattice curvatures arising from misaligned Burgers vectors with further elastic contributions. Over extended crystal growth, these secondary components align the lattice to rotate about either the <001> or <010> crystal axes forming repeating metastructures of lattice orientation with periodicity 20–160 microns in length. The mechanistic approach used in this work may be expanded to other systems with known slip systems to better understand and design macroperiodic metastructures.

36 MATERIALS SCIENCE↗
NASA NTRS1998

Advanced thermoelectric materials with enhanced crystal lattice structure and methods of preparation

New skutterudite phases including Ru.sub.0.5 Pd.sub.0.5 Sb.sub.3, RuSb.sub.2 Te, and FeSb.sub.2 Te, have been prepared having desirable thermoelectric properties. In addition, a novel thermoelectric device has been prepared using skutterudite phase Fe.sub.0.5 Ni.sub.0.5 Sb.sub.3. The skutterudite-type crystal lattice structure of these semiconductor compounds and their enhanced thermoelectric properties results in semiconductor materials which may be used in the fabrication of thermoelectric elements to substantially improve the efficiency of the resulting thermoelectric device. Semiconductor materials having the desired skutterudite-type crystal lattice structure may be prepared in accordance with the present invention by using powder metallurgy techniques. Measurements of electrical and thermal transport properties of selected semiconductor materials prepared in accordance with the present invention, demonstrated high Hall mobilities and good Seebeck coefficients. These materials have low thermal conductivity and relatively low electrical resistivity, and are good candidates for low temperature thermoelectric applications.

Fleurial, Jean-Pierre↗
DOE OSTI2023

Evolution of magnetism, valence, and crystal lattice in EuCd 2 As 2 under pressure

EuCd 2 As 2 has been proposed to be one of the ideal platforms as an intrinsic topological magnetic system, potentially hosting a single pair of Weyl points when it is tuned into the ferromagnetic state with spins aligned out of plane by either external pressure or chemical doping. To investigate the possible realization of an ideal topological state, we have systematically investigated pressure control of the magnetic state, valence, and crystal structure using synchrotron-based time-domain Mössbauer spectroscopy, x-ray absorption spectroscopy, and powder x-ray diffraction. Our experimental results show that the magnetic configuration remains mostly in plane under pressure up to 42.8 GPa and pressure effectively enhances the magnetic ordering temperature. Meanwhile, Eu ions remain divalent when subjected to pressure up to 35.9 GPa, and the trigonal crystal lattice is maintained up to 34.6 GPa. Our work provides valuable experimental data to benchmark future theoretical studies in magnetic topological materials.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2024

Imaging extended single crystal lattice distortion fields with multi-peak Bragg ptychography

Recent advances in phase-retrieval-based x-ray imaging methods have demonstrated the ability to reconstruct 3D distortion vector fields within a nanocrystal by using coherent diffraction information from multiple crystal Bragg reflections. However, these works do not provide a solution to the challenges encountered in imaging lattice distortions in crystals with significant defect content that result in phase wrapping. Moreover, these methods only apply to isolated crystals smaller than the x-ray illumination, and therefore cannot be used for imaging of distortions in extended crystals. We introduce multi-peak Bragg ptychography which addresses both challenges via an optimization framework that combines stochastic gradient descent and phase unwrapping methods for robust image reconstruction of lattice distortions and defects in extended crystals. Our work uses modern automatic differentiation toolsets so that the method is easy to extend to other settings and easy to implement in high-performance computers. This work is particularly timely given the broad interest in using the increased coherent flux in fourth-generation synchrotrons for innovative material research.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Local Thermal Conductivity Patterning in Rotating Lattice Crystals of Anisotropic Sb 2 S 3

The ability to control material heat transport properties over space and time can drive advanced functionalities in thermal management for electronics and system-on-chip, and enable thermal circuits. Despite the technological relevance, there are limited demonstrations of local thermal property control. Rotating lattice single (RLS) crystals—formed via laser-induced crystallization of an amorphous substrate—offer a novel avenue for local crystal engineering, unlocking opportunities for microscale property patterning. Here, thermal conductivity (𝜅) imaging is applied to RLS crystals of Sb2S3 to resolve microscale 𝜅 variations across patterned regions. Amorphous areas exhibit 𝜅 as low as 0.6 Wm −1 K −1 , while crystalline regions display periodic 𝜅 variations from 0.7 to over 2.5 Wm −1 K −1 . These variations correspond to changes in crystal orientation, revealing marked 𝜅 anisotropy. The crystal out-of-plane direction (c axis)—featuring van der Waals bonds—shows amorphous-like transport, whereas in-plane directions (a, b axes) exhibit 3.5x and 1.7x larger 𝜅, respectively. First-principles calculations, in excellent agreement with experiments, suggest that the in-plane anisotropy originates from expressed Sb lone pairs, which impart a corrugation along the b axis affecting bond stiffness and 𝜅. These findings demonstrate microscale control of thermal properties via laser-processed metastructures, with significant implications for next-generation thermal management.

14 SOLAR ENERGY↗
DOE OSTI2026

Mesoscale atomic engineering in a crystal lattice

Controlling individual atoms using lasers, ion traps and scanning probe tips has transformed our understanding of matter and enabled breakthroughs in quantum science. Extending this control into three-dimensional (3D) solids and across mesoscopic scales, however, remains a foundational challenge. Electron irradiation in electron microscopes is known to induce atomic displacements, and atomic manipulation has been proposed and demonstrated. Yet repeated and deterministic control has remained elusive. Here, in this study, we demonstrate deterministic atomic engineering in a 3D crystal, creating ordered arrangements of more than 40,000 user-defined defects within minutes across a 150 nm × 100 nm × 13 nm volume. By steering individual Cr atoms in the magnetic semiconductor CrSBr into selected interstitial sites using an electron beam directed with sub-20-pm-scale accuracy, we create vacancy–interstitial complexes. The resulting impurity array forms a mesoscale crystal embedded within the host lattice, a new form of engineered artificial matter that remains stable at room temperature and outside the microscope. By tracking Cr atom displacements, we identify conditions under which the defect structures are predictable. Our calculations suggest that these defects form correlated impurity states with intra-defect optical transitions and inter-defect kinetic and Coulomb interactions. This establishes a generalizable platform for atomic defect engineering at mesoscopic, and potentially macroscopic, scales, opening opportunities for scalable quantum technologies, including deterministic colour-centre placement, quantum simulation of many-body lattice models and atomic-scale manufacturing.

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2023

Coupling of magnetism, crystal lattice, and transport in EuCuP and EuCuAs

EuCuP and EuCuAs are members of a family of materials with candidates for realizing magnetically tuned electronic topology. Here, in this work, the magnetic phase transitions and magnetoelastic coupling of EuCuP and EuCuAs have been investigated. Around the Curie temperature, the thermal expansion coefficient and specific-heat capacity of EuCuP are found to have two closely spaced features, at approximately 30 and 31.3 K, which may indicate a cascading magnetic transition or perhaps an electronic transition closely coupled to the magnetic ordering. The zero-field magnetoelastic coupling appears to be stronger in EuCuP than in EuCuAs, and field-dependent measurements suggest this is due to the dominant ferromagnetic interaction in EuCuP as opposed to antiferromagnetic order in EuCuAs below T N =13.5 K. Thermal expansion is anisotropic around T N in EuCuAs, with a maximum expansion along [001] occurring above T N prior to a stiffening of this c -axis component on cooling through T N ; the expansion of the basal plane has a lambda-like peak centered slightly above T N . Matching these behaviors, the ac susceptibility data for EuCuAs suggest the presence of strong ferromagnetic correlations above T N in the vicinity where the c-axis expansion peaks. Both compounds possess similar electrical and thermoelectric transport behaviors, with short-range magnetic order likely playing an important role above T C or T N . Transport properties suggest these are predominantly hole doped due to intrinsic defects, and narrow-gap semiconducting or semimetallic behavior may be achievable if the underlying defects can be tuned.

36 MATERIALS SCIENCE↗
NASA NTRS2010

Crystal Lattice Controlled SiGe Thermoelectric Materials with High Figure of Merit

Direct energy conversion between thermal and electrical energy, based on thermoelectric (TE) effect, has the potential to recover waste heat and convert it to provide clean electric power. The energy conversion efficiency is related to the thermoelectric figure of merit ZT expressed as ZT=S(exp 2)(sigma)T/Kappa, T is temperature, S is the Seebeck coefficient, sigma is conductance and Kappa is thermal conductivity. For a lower thermal conductivity Kappa and high power factor (S(exp 2)(sigma)), our current strategy is the development of rhombohedrally strained single crystalline SiGe materials that are highly [111]-oriented twinned. The development of a SiGe "twin lattice structure (TLS)" plays a key role in phonon scattering. The TLS increases the electrical conductivity and decreases thermal conductivity due to phonon scattering at stacking faults generated from the 60 X rotated primary twin structure. To develop high performance materials, the substrate temperature, chamber working pressure, and DC sputtering power are controlled for the aligned growth production of SiGe layer and TLS on a c-plane sapphire. Additionally, a new elevated temperature thermoelectric characterization system, that measures the thermal diffusivity and Seebeck effect nondestructively, was developed. The material properties were characterized at various temperatures and optimized process conditions were experimentally determined. The present paper encompasses the technical discussions toward the development of thermoelectric materials and the measurement techniques.

Kim, Hyun-Jung↗
DOE OSTI2022

Curved lattices of crystals formed in glass

Atomic arrangements systemically deviating from the classic definition of single crystal lattice have been known in spherulites for over a century. However, their unusual curved lattice could not be exploited for useful applications due to their uncontrolled orientations and lattice curvatures. Heating of glass with focused laser, electron or x-ray beam has yielded well-defined conditions for forming single crystal architectures. Furthermore, by controlling the conditions of irradiation and confinement by glass matrix for a given system, desired lattice curvature (rotations and twists) can be reproducibly introduced into these crystals. Here, we review several examples of laser-fabricated crystals with curved lattices in glass using a common coordinate system, which helps to establish correlations between processing parameters and lattice curvature. Here, the mechanisms of lattice deformations are discussed along with potential methods to control the orientation of the initially formed seeds that determine the lattice orientations of the end product. The recent developments of laser-fabrication of single crystal architecture in glass with controlled heating profile appear promising for engineering the curvature of their lattices.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Importance of dynamic lattice effects for crystal field excitations in the quantum spin ice candidate Pr 2 Zr 2 O 7

We explore dynamic interactions between the crystal lattice and magnetic degrees of freedom in a frustrated magnetic system using the example of a pyrochlore quantum spin-ice candidate Pr 2 Zr 2 O 7 . Using Raman scattering spectroscopy we demonstrate that crystal electric field excitations of Pr3+, which define the magnetic properties of Pr 2 Zr 2 O 7 , cannot be understood within a model of a static lattice. We identify vibronic interactions with a phonon which lead to a splitting of a doublet crystal field excitation at around 55 meV. We also observe an unconventional behavior of a splitting of the non-Kramers ground state doublet of Pr 3+ , revealed by observing excitations to the first excited singlet state $E$$^{0}_{g}$ → A 1 g at around 10 meV. The splitting has a strong temperature dependence, where the doublet structure is most prominent between 50 and 100 K, and the weight of one of the components strongly decreases on cooling contrary to simple thermal population tendency. Furthermore, we suggest a static or dynamic deviation of Pr 3+ from the position in the ideal crystal structure can be the origin of the effect, with the deviation strongly decreasing at low temperatures.

36 MATERIALS SCIENCE↗
NASA NTRS2003

Physics of Biocrystals and Their Growth

Recent results on binding between protein molecules in crystal lattice, crystal-solution surface energy, elastic properties and strength and spontaneous crystal cracking are reviewed and discussed in the first half of the paper (Sections 2-5). In the second part, some basic approaches to solubility of proteins is followed by overview on crystal nucleation and growth (Section 6). It is argued that variability of mixing in batch crystallization may be a source scattering of crystal number ultimately appearing in the batch (Section 7). Frequency at which new molecules join crystal lattice is related to the observable crystal growth rate. Numerical criteria to discriminate diffusion and kinetic limited growth are discussed on this basis in Section 8. In Section 9, creation of defects is discussed with the emphasis on the role of impurities and convection in macromolecular crystal perfection.

Chernov, A.↗
NASA NTRS2004

Protein Crystals and their Growth

Recent results on binding between protein molecules in crystal lattice, crystal-solution surface energy, elastic properties and strength and spontaneous crystal cracking are reviewed and discussed in the first half of this paper (Sea 2-4). In the second par&, some basic approaches to solubility of proteins are followed by overview on crystal nucleation and growth (Sec 5). It is argued that variability of mixing in batch crystallization may be a source for scattering of crystal number ultimately appearing in the batch. Frequency at which new molecules join crystal lattice is measured by kinetic coefficient and related to the observable crystal growth rate. Numerical criteria to discriminate diffusion and kinetic limited growth are discussed on this basis in Sec 7. In Sec 8, creation of defects is discussed with the emphasis on the role of impurities and convection on macromolecular crystal I;erfection.

Chernov, A. A.↗