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At least 343 records · Page 19
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Magnetic anisotropy in uranium monosulfide probed by magnetic torque measurements

We have studied the magnetic torque in uranium monosulfide (US) single crystals to explore the magnetic anisotropy in this material. Uranium monosulfide crystallizes in a cubic, NaCl-type of crystal structure and exhibits the largest magnetocrystalline anisotropy observed in cubic systems. By performing detailed torque measurements we observe a strongly anisotropic behavior in the paramagnetic phase due to crystal defects and quadrupolar pair interactions. Our studies also confirm the presence of a large anisotropy in the ferromagnetic state of the US system with the <100>, <111>, and <110> directions being the hard, easy, and intermediate axes, respectively. Furthermore, the anisotropy in the paramagnetic phase shows similar characteristics to the anisotropy observed in the ferromagnetic phase, as characterized by second and fourth rank susceptibility terms. The similarity of the anisotropic behaviors in paramagnetic and ferromagnetic phases is the consequence of strong magnetoelastic properties in this system, which possibly lead to the rhombohedral structural distortion, not only in the ferromagnetic phase but also in the paramagnetic phase (induced by applied magnetic field).

36 MATERIALS SCIENCE↗
DOE OSTI2022

Communication—Electrodeposition of Indium Directly on Silicon

Direct electrodeposition of indium onto silicon paves the way for advances in microelectronics, photovoltaics, and optoelectronics. Indium is generally electrodeposited onto silicon utilizing a physically or thermally deposited metallic seed layer. Eliminating this layer poses benefits in microelectronics by reducing resistive interfaces and in vapor-liquid-solid conversion to III-V material by allowing direct contact to the single-crystal silicon substrate for epitaxial conversion. We investigated conditions to directly electrodeposit indium onto n-type Si(100). We illustrate that a two-step galvanostatic plating at low temperatures can consistently produce smooth, continuous films of indium over large areas, in bump morphologies, and conformally into inverted pyramids.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Highly Extensible X-ray Diffraction Toolkit

This code has been previous released as open source under LLNL-CODE-529294. The HEXRD program comprises a library of X-ray diffraction analysis tools and a stand-alone GUI application. While there are many software packages that provide similar capabilities, HEXRD was designed to provide an extremely flexible and extensible basis for describing a broad array of X-ray diffraction instruments; this includes both mono- and poly-chromatic modalities as well as poly- and single-crystal samples. The high-level objects include Material: an abstraction for defining crystalline materials, including unit cell parameters and anisotropic elastic moduli Imageseries: an interface for series of diffraction images containing one or more frames, including provisions for metadata. Instrument: an abstraction of an X-ray diffraction instrument including support for the definition of multiple detector elements as well as powder, Laue, and mono-chromatic single/multi-grain diffraction analysis modalities (including attendant calibration routines). The hexrdgui package is a standalone PySide2/Qt5 GUI built on top of hexrd. The 0.8.1 release includes various bug fixes as well as some new functionality in the GUI, including: o Enhancements to the import tools for LLNL diffraction instruemtns (PXRDIP and TARDIS) o The ability to save 1-d LeBail fits of integrated diffraction spectra.

Barton, NathanR.↗
DOE OSTI2021

Seismic Visibility of Eclogite in the Earth’s Upper Mantle—Implications From High Pressure‐Temperature Single‐Crystal Elastic Properties of Omphacite

Abstract Identifying and locating the geochemical and geophysical heterogeneities in the Earth’s interior is one of the most important and challenging tasks for the deep Earth scientists. Subducted oceanic crust metamorphizes into the dense eclogite in the upper mantle and is considered as a major cause of geochemical and geophysical heterogeneities in the deep Earth. In order to detect eclogitic materials inside the Earth, precise measurements of the high pressure‐temperature single‐crystal elasticity of major minerals in eclogite are thus exceedingly important. Omphacite, a Na,Al‐bearing clinopyroxene, constitutes up to 75 vol% of eclogite. In the present study, we performed the first high pressure‐temperature single‐crystal elasticity measurements of omphacite using Brillouin spectroscopy. Utilizing the finite‐strain approach, we obtained the following thermoelastic parameters for omphacite: K S0 ’ = 4.5(1), G 0 ’ = 1.53(5), ∂K S0 /∂ T = −0.029(5) GPa/K, ∂G 0 /∂ T = −0.013(5) GPa/K, with K S0 = 123(3) GPa, G 0 = 74(2) GPa, and ρ 0 = 3.34(1) g/cm 3 . We found that the seismic velocities of undeformed eclogite are similar to pyrolite at the depths of 200–300 and 410–500 km, thus eclogite is seismically invisible at these depths. Combined with the lattice‐preferred orientations of the omphacite in naturally deformed eclogites, we also modeled seismic anisotropy of eclogite at various pressure‐temperature conditions. A 10 km thick subducted eclogitic crust can result in ∼0.2 s shear wave splitting in the Earth’s upper mantle.

Hao, Ming↗
DOE OSTI2021

Single crystal growth and characterization of new Zintl phase Ca 9 Zn 3.1 In 0.9 Sb 9

Complex Zintl phases have yielded a large variety of promising new thermoelectric materials. Here we report the discovery of the new Zintl phase Ca 9 (Zn 1– x In x ) 4 Sb 9 ( x ~ 0.9), needle-like crystals of which were serendipitously obtained from an In- and Sb-rich flux. Although its composition is reminiscent of Ca 9 Zn 4+ x Sb 9 , an excellent thermoelectric material with zT > 1, the substitution of In on the Zn site leads to the formation of an entirely new structure type. Single crystal X-ray diffraction revealed a structure characterized by T Sb 4 tetrahedra ( T = statistically disordered Zn and In atoms) and ZnSb 3 triangular units, which share common corners to form [ T 4 Sb 9 ] 18– polyanions. The average structure was found to have hexagonal symmetry. The valence electron count in this heavily-disordered structure appears to follows the Zintl-Klemm rules, suggesting semiconducting behavior. Single crystal electrical conductivity and Seebeck coefficient measurements support this conclusion, suggesting that the as-grown crystals are degenerate p -type semiconductors.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Materials Data on H2O2 by Materials Project

H2O2 crystallizes in the tetragonal P4_12_12 space group. The structure is zero-dimensional and consists of eight water molecules. H is bonded in a single-bond geometry to one O atom. The H–O bond length is 1.01 Å. O is bonded in a single-bond geometry to one H atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on PbS by Materials Project

PbS crystallizes in the monoclinic C2 space group. The structure is zero-dimensional and consists of four lead;sulfanide molecules. Pb2+ is bonded in a distorted single-bond geometry to one S2- atom. The Pb–S bond length is 2.69 Å. S2- is bonded in a single-bond geometry to one Pb2+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on SN by Materials Project

NS crystallizes in the monoclinic P2_1/c space group. The structure is zero-dimensional and consists of four NS clusters. N1+ is bonded in a distorted single-bond geometry to one S1- atom. The N–S bond length is 1.49 Å. S1- is bonded in a distorted single-bond geometry to one N1+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CsLa by Materials Project

CsLa crystallizes in the hexagonal P6_3mc space group. The structure is zero-dimensional and consists of two CsLa clusters. Cs is bonded in a distorted single-bond geometry to one La atom. The Cs–La bond length is 3.58 Å. La is bonded in a distorted single-bond geometry to one Cs atom.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Impact of 2D–3D Heterointerface on Remote Epitaxial Interaction through Graphene

Remote epitaxy has drawn attention as it offers epitaxy of functional materials that can be released from the substrates with atomic precision, thus enabling production and heterointegration of flexible, transferrable, and stackable freestanding single-crystalline membranes. In addition, the remote interaction of atoms and adatoms through two-dimensional (2D) materials in remote epitaxy allows investigating and utilizing electrical/chemical/physical coupling of bulk (3D) materials via 2D materials (3D-2D-3D coupling). Here, we unveil the respective roles and impacts of the substrate material, graphene, substrate-graphene interface, and epitaxial material for electrostatic coupling of these materials, which governs cohesive ordering and can lead to single-crystal epitaxy in the overlying film. Further, we show that simply coating a graphene layer on wafers does not guarantee successful implementation of remote epitaxy, since atomically precise control of the graphene-coated interface is required, and provide key considerations for maximizing the remote electrostatic interaction between the substrate and adatoms. This was enabled by exploring various material systems and processing conditions, and we demonstrate that the rules of remote epitaxy vary significantly depending on the ionicity of material systems as well as the graphene-substrate interface and the epitaxy environment. The general rule of thumb discovered here enables expanding 3D material libraries that can be stacked in freestanding form.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Nanoscale Polarization-Dependent Young’s Modulus of Ferroelectric BaTiO 3 Single Crystals

Flexoelectric fields produced by strong strain gradients at the nanoscale couple to ferroelectric polarization, promoting changes in the mechanical properties of ferroelectric materials as a function of the direction of the ferroelectric polarization. In this work, we calculate the asymmetry in the Young’s modulus found in oppositely polarized out-of-plane domains of BaTiO 3 single crystals by means of contact resonance AFM, and we evaluate its impact on the electromechanical response as measured by piezoresponse force microscopy, both using band excitation modes. Furthermore, we analyze the electromechanical response of the different BaTiO 3 domains using k-means to build up their mean elastic and electromechanical features and quantify the flexoelectrically induced modulation of the Young’s modulus. Finally, we discuss the use of contact Kelvin probe force microscope measurements to decouple electrostatic artifacts from purely piezoelectric ones when flexoelectric coupling appears.

BaTiO 3 single crystals↗
DOE OSTI2020

Materials Data on H2O2 by Materials Project

H2O2 crystallizes in the tetragonal P4_12_12 space group. The structure is zero-dimensional and consists of eight water molecules. H is bonded in a distorted single-bond geometry to one O atom. The H–O bond length is 1.01 Å. O is bonded in a distorted single-bond geometry to one H atom.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Serrated flow in $\mathrm{NaI:Tl}$ scintillator crystals

We report the serrated-flow behavior is an important phenomenon that unveils material-deformation mechanisms, as reported for various kinds of materials. NaI doped with Tl (NaI:Tl) is unique among scintillation materials in that the structure contains glide planes that are linked to serration behavior. In the present work, single crystals of NaI:Tl were subjected to room-temperature compression experiments at different strain rates. The serrated flow was observed, and complexity and multifractal analyses were performed to analyze the serration behavior. The findings revealed that the strain rate had a pronounced effect on the complexity and multifractality of the serrated flow, similar to what has been found in other alloy systems. The results also indicate that there may be a strong link between the complexity of the serrated flow behavior and the heterogeneity of the underlying dynamics. It is expected that the present work could be a step toward a better understanding of the deformation behavior and forgeability of NaI:Tl single crystals.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sr4(RuO4)3 by Materials Project

Sr4(RuO4)3 crystallizes in the monoclinic Pm space group. The structure is three-dimensional. there are sixteen inequivalent Sr2+ sites. In the first Sr2+ site, Sr2+ is bonded to twelve O2- atoms to form SrO12 cuboctahedra that share corners with twelve SrO12 cuboctahedra, faces with four SrO12 cuboctahedra, and faces with five RuO6 octahedra. There are a spread of Sr–O bond distances ranging from 2.77–2.88 Å. In the second Sr2+ site, Sr2+ is bonded to twelve O2- atoms to form SrO12 cuboctahedra that share corners with twelve SrO12 cuboctahedra, faces with four SrO12 cuboctahedra, and faces with seven RuO6 octahedra. There are a spread of Sr–O bond distances ranging from 2.70–2.90 Å. In the third Sr2+ site, Sr2+ is bonded to twelve O2- atoms to form SrO12 cuboctahedra that share corners with twelve SrO12 cuboctahedra, faces with four SrO12 cuboctahedra, and faces with seven RuO6 octahedra. There are a spread of Sr–O bond distances ranging from 2.72–2.85 Å. In the fourth Sr2+ site, Sr2+ is bonded to twelve O2- atoms to form distorted SrO12 cuboctahedra that share corners with seven SrO12 cuboctahedra, corners with two equivalent RuO6 octahedra, faces with seven SrO12 cuboctahedra, and faces with five RuO6 octahedra. The corner-sharing octahedral tilt angles are 24°. There are a spread of Sr–O bond distances ranging from 2.61–3.02 Å. In the fifth Sr2+ site, Sr2+ is bonded to twelve O2- atoms to form SrO12 cuboctahedra that share corners with twelve SrO12 cuboctahedra, faces with four SrO12 cuboctahedra, and faces with five RuO6 octahedra. There are a spread of Sr–O bond distances ranging from 2.77–2.87 Å. In the sixth Sr2+ site, Sr2+ is bonded to twelve O2- atoms to form distorted SrO12 cuboctahedra that share corners with five SrO12 cuboctahedra, a cornercorner with one RuO6 octahedra, faces with seven SrO12 cuboctahedra, and faces with six RuO6 octahedra. The corner-sharing octahedral tilt angles are 29°. There are a spread of Sr–O bond distances ranging from 2.64–3.09 Å. In the seventh Sr2+ site, Sr2+ is bonded to twelve O2- atoms to form distorted SrO12 cuboctahedra that share corners with seven SrO12 cuboctahedra, corners with two equivalent RuO6 octahedra, faces with seven SrO12 cuboctahedra, and faces with five RuO6 octahedra. The corner-sharing octahedral tilt angles are 23°. There are a spread of Sr–O bond distances ranging from 2.60–3.02 Å. In the eighth Sr2+ site, Sr2+ is bonded to twelve O2- atoms to form distorted SrO12 cuboctahedra that share corners with five SrO12 cuboctahedra, a cornercorner with one RuO6 octahedra, faces with seven SrO12 cuboctahedra, and faces with six RuO6 octahedra. The corner-sharing octahedral tilt angles are 29°. There are a spread of Sr–O bond distances ranging from 2.62–3.11 Å. In the ninth Sr2+ site, Sr2+ is bonded to twelve O2- atoms to form SrO12 cuboctahedra that share corners with twelve SrO12 cuboctahedra, faces with five SrO12 cuboctahedra, and faces with five RuO6 octahedra. There are a spread of Sr–O bond distances ranging from 2.73–2.86 Å. In the tenth Sr2+ site, Sr2+ is bonded to twelve O2- atoms to form SrO12 cuboctahedra that share corners with twelve SrO12 cuboctahedra, faces with five SrO12 cuboctahedra, and faces with seven RuO6 octahedra. There are a spread of Sr–O bond distances ranging from 2.70–2.92 Å. In the eleventh Sr2+ site, Sr2+ is bonded to twelve O2- atoms to form SrO12 cuboctahedra that share corners with twelve SrO12 cuboctahedra, faces with five SrO12 cuboctahedra, and faces with five RuO6 octahedra. There are a spread of Sr–O bond distances ranging from 2.74–2.86 Å. In the twelfth Sr2+ site, Sr2+ is bonded to twelve O2- atoms to form SrO12 cuboctahedra that share corners with twelve SrO12 cuboctahedra, faces with five SrO12 cuboctahedra, and faces with seven RuO6 octahedra. There are a spread of Sr–O bond distances ranging from 2.71–2.91 Å. In the thirteenth Sr2+ site, Sr2+ is bonded to twelve O2- atoms to form distorted SrO12 cuboctahedra that share corners with eight SrO12 cuboctahedra, a cornercorner with one RuO6 octahedra, faces with six SrO12 cuboctahedra, and faces with six RuO6 octahedra. The corner-sharing octahedral tilt angles are 27°. There are a spread of Sr–O bond distances ranging from 2.63–3.07 Å. In the fourteenth Sr2+ site, Sr2+ is bonded in a 12-coordinate geometry to twelve O2- atoms. There are a spread of Sr–O bond distances ranging from 2.61–3.10 Å. In the fifteenth Sr2+ site, Sr2+ is bonded to twelve O2- atoms to form distorted SrO12 cuboctahedra that share corners with eight SrO12 cuboctahedra, a cornercorner with one RuO6 octahedra, faces with six SrO12 cuboctahedra, and faces with six RuO6 octahedra. The corner-sharing octahedral tilt angles are 27°. There are a spread of Sr–O bond distances ranging from 2.64–3.08 Å. In the sixteenth Sr2+ site, Sr2+ is bonded in a 12-coordinate geometry to twelve O2- atoms. There are a spread of Sr–O bond distances ranging from 2.60–3.11 Å. There are twelve inequivalent Ru+5.33+ sites. In the first Ru+5.33+ site, Ru+5.33+ is bonded to six O2- atoms to form RuO6 octahedra that share corners with four RuO6 octahedra and faces with eight SrO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 0–4°. There are a spread of Ru–O bond distances ranging from 1.87–2.00 Å. In the second Ru+5.33+ site, Ru+5.33+ is bonded to six O2- atoms to form RuO6 octahedra that share corners with five RuO6 octahedra and faces with six SrO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 1–5°. There are a spread of Ru–O bond distances ranging from 1.87–2.04 Å. In the third Ru+5.33+ site, Ru+5.33+ is bonded to six O2- atoms to form RuO6 octahedra that share a cornercorner with one SrO12 cuboctahedra, corners with three RuO6 octahedra, and faces with seven SrO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 4–5°. There are a spread of Ru–O bond distances ranging from 1.85–2.08 Å. In the fourth Ru+5.33+ site, Ru+5.33+ is bonded to six O2- atoms to form RuO6 octahedra that share a cornercorner with one SrO12 cuboctahedra, corners with three RuO6 octahedra, and faces with seven SrO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 5–6°. There are a spread of Ru–O bond distances ranging from 1.85–2.09 Å. In the fifth Ru+5.33+ site, Ru+5.33+ is bonded to six O2- atoms to form RuO6 octahedra that share corners with four RuO6 octahedra and faces with eight SrO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 0–5°. There are a spread of Ru–O bond distances ranging from 1.87–2.00 Å. In the sixth Ru+5.33+ site, Ru+5.33+ is bonded to six O2- atoms to form RuO6 octahedra that share corners with five RuO6 octahedra and faces with six SrO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 1–5°. There are a spread of Ru–O bond distances ranging from 1.87–2.04 Å. In the seventh Ru+5.33+ site, Ru+5.33+ is bonded to six O2- atoms to form RuO6 octahedra that share corners with five RuO6 octahedra and faces with seven SrO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 1–5°. There are a spread of Ru–O bond distances ranging from 1.87–2.03 Å. In the eighth Ru+5.33+ site, Ru+5.33+ is bonded to six O2- atoms to form RuO6 octahedra that share corners with four RuO6 octahedra and faces with seven SrO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 0–3°. There are a spread of Ru–O bond distances ranging from 1.87–1.99 Å. In the ninth Ru+5.33+ site, Ru+5.33+ is bonded to six O2- atoms to form RuO6 octahedra that share corners with five RuO6 octahedra and faces with seven SrO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 1–6°. There are a spread of Ru–O bond distances ranging from 1.87–2.03 Å. In the tenth Ru+5.33+ site, Ru+5.33+ is bonded to six O2- atoms to form RuO6 octahedra that share corners with four RuO6 octahedra and faces with seven SrO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 0–3°. There are a spread of Ru–O bond distances ranging from 1.87–2.00 Å. In the eleventh Ru+5.33+ site, Ru+5.33+ is bonded to six O2- atoms to form RuO6 octahedra that share corners with three SrO12 cuboctahedra, corners with three RuO6 octahedra, and faces with six SrO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 3–5°. There are a spread of Ru–O bond distances ranging from 1.87–2.06 Å. In the twelfth Ru+5.33+ site, Ru+5.33+ is bonded to six O2- atoms to form RuO6 octahedra that share corners with three SrO12 cuboctahedra, corners with three RuO6 octahedra, and faces with six SrO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 3–5°. There are a spread of Ru–O bond distances ranging from 1.87–2.06 Å. There are thirty-two inequivalent O2- sites. In the first O2- site, O2- is bonded in a 5-coordinate geometry to four Sr2+ and one Ru+5.33+ atom. In the second O2- site, O2- is bonded in a distorted linear geometry to four Sr2+ and two Ru+5.33+ atoms. In the third O2- site, O2- is bonded in a distorted single-bond geometry to four Sr2+ and one Ru+5.33+ atom. In the fourth O2- site, O2- is bonded in a distorted linear geometry to four Sr2+ and two Ru+5.33+ atoms. In the fifth O2- site, O2- is bonded in a distorted linear geometry to four Sr2+ and two Ru+5.33+ atoms. In the sixth O2- site, O2- is bonded in a distorted linear geometry to four Sr2+ and two Ru+5.33+ atoms. In the seventh O2- site, O2- is bonded in a 1-coordinate geometry to four Sr2+ and one Ru+5.33+ atom. In the eighth O2- site, O2- is bonded in a 1-coordinate geometry to four Sr2+ and one Ru+5.33+ atom. In the ninth O2- site, O2- is bonded in a 1-coordinate geometry to four Sr2+ and one Ru+5.33+ atom. In the tenth O2- site, O2- is bonded in a 1-coordinate geometry to four Sr2+ and one Ru+5.33+ atom. In the eleventh O2- site, O2- is bonded in a 1-coordinate geometry to four Sr2+ and one Ru+5.33+ atom. In the twelfth O2- site, O2- is bonded in a 1-coordinate geometry to four Sr2+ and one Ru+5.33+ atom. In the thirteenth O2- site, O2- is bonded in a distorted linear geometry to four Sr2+ and two Ru+5.33+ atoms. In the fourteenth O2- site, O2- is bonded in a distorted linear geometry to four Sr2+ and two Ru+5.33+ atoms. In the fifteenth O2- site, O2- is bonded in a 1-coordinate geometry to four Sr2+ and one Ru+5.33+ atom. In the sixteenth O2- site, O2- is bonded in a 1-coordinate geometry to four Sr2+ and one Ru+5.33+ atom. In the seventeenth O2- site, O2- is bonded in a 2-coordinate geometry to four Sr2+ and two Ru+5.33+ atoms. In the eighteenth O2- site, O2- is bonded in a distorted linear geometry to four Sr2+ and two Ru+5.33+ atoms. In the nineteenth O2- site, O2- is bonded in a distorted linear geometry to four Sr2+ and two Ru+5.33+ atoms. In the twentieth O2- site, O2- is bonded in a distorted linear geometry to four Sr2+ and two Ru+5.33+ atoms. In the twenty-first O2- site, O2- is bonded in a distorted linear geometry to four Sr2+ and two Ru+5.33+ atoms. In the twenty-second O2- site, O2- is bonded in a distorted linear geometry to four Sr2+ and two Ru+5.33+ atoms. In the twenty-third O2- site, O2- is bonded in a distorted single-bond geometry to four Sr2+ and one Ru+5.33+ atom. In the twenty-fourth O2- site, O2- is bonded in a 1-coordinate geometry to four Sr2+ and one Ru+5.33+ atom. In the twenty-fifth O2- site, O2- is bonded in a 5-coordinate geometry to four Sr2+ and one Ru+5.33+ atom. In the twenty-sixth O2- site, O2- is bonded in a distorted single-bond geometry to four Sr2+ and one Ru+5.33+ atom. In the twenty-seventh O2- site, O2- is bonded in a distorted linear geometry to four Sr2+ and two Ru+5.33+ atoms. In the twenty-eighth O2- site, O2- is bonded in a distorted linear geometry to four Sr2+ and two Ru+5.33+ atoms. In the twenty-ninth O2- site, O2- is bonded in a distorted linear geometry to four Sr2+ and two Ru+5.33+ atoms. In the thirtieth O2- site, O2- is bonded in a distorted single-bond geomet

36 MATERIALS SCIENCE↗
DOE OSTI2022

Graphene Nanopattern for Single-Crystal Film Growth, Defect Reduction and Layer Transfer

Thin film heterostructures are key building blocks for advanced electronic and optoelectronic devices. For this, direct heteroepitaxy has been pursued for decades, although it has been challenging to reduce crystal defects stemming from lattice mismatches and thermal mismatches between materials. The layer transfer method has been proposed as an alternative approach, wherein dissimilar materials are separately grown and then hetero-integrated. However, the applicability of layer transfer techniques is limited by several technical challenges, such as controllability, throughput, and damage to the substrate. Remote epitaxy, which is a recently developed method to produce single-crystalline membranes, is a promising approach but cannot be applied to elemental materials such as Si and Ge. In this work, we report graphene nanopattern as a universal template for the growth of single-crystal thin films that can be exfoliated as a freestanding form. This is realized by the chemical inertness of graphene, which allows selective nucleation at the exposed region, followed by lateral overgrowth onto graphene to form a planarized thin film. By employing graphene nanopattern, both group IV and III-V materials are utilized as the substrate as well as the epilayer. The epilayer can be exfoliated at the graphene interface because partially covered graphene effectively weakens the interface, which is corroborated by theoretical analyses of spalling theory. We reveal that graphene nanopattern not only works as a weakened interface for exfoliation, but also allows for dislocation reduction in heteroepitaxial films. This is because of the flexibility and the dangling-bond-free nature of graphene, which provides an additional path for strain relaxation. Therefore, these results represent a meaningful step toward production of high-quality single-crystal membranes that can be hetero-integrated.

Kim, Hyunseok↗
DOE OSTI2022

Graphene Nanopattern for Single-Crystal Film Growth, Defect Reduction and Layer Transfer

Thin film heterostructures are key building blocks for advanced electronic and optoelectronic devices. For this, direct heteroepitaxy has been pursued for decades, although it has been challenging to reduce crystal defects stemming from lattice mismatches and thermal mismatches between materials. The layer transfer method has been proposed as an alternative approach, wherein dissimilar materials are separately grown and then hetero-integrated. However, the applicability of layer transfer techniques is limited by several technical challenges, such as controllability, throughput, and damage to the substrate. Remote epitaxy, which is a recently developed method to produce single-crystalline membranes, is a promising approach but cannot be applied to elemental materials such as Si and Ge. In this work, we report graphene nanopattern as a universal template for the growth of single-crystal thin films that can be exfoliated as a freestanding form. This is realized by the chemical inertness of graphene, which allows selective nucleation at the exposed region, followed by lateral overgrowth onto graphene to form a planarized thin film. By employing graphene nanopattern, both group IV and III-V materials are utilized as the substrate as well as the epilayer. The epilayer can be exfoliated at the graphene interface because partially covered graphene effectively weakens the interface, which is corroborated by theoretical analyses of spalling theory. We reveal that graphene nanopattern not only works as a weakened interface for exfoliation, but also allows for dislocation reduction in heteroepitaxial films. This is because of the flexibility and the dangling-bond-free nature of graphene, which provides an additional path for strain relaxation. Therefore, these results represent a meaningful step toward production of high-quality single-crystal membranes that can be hetero-integrated.

Kim, Hyunseok↗
DOE OSTI2020

Materials Data on Li4V3P8O29 by Materials Project

Li4V3P8O29 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are eight inequivalent Li1+ sites. In the first Li1+ site, Li1+ is bonded in a 4-coordinate geometry to four O2- atoms. There are a spread of Li–O bond distances ranging from 1.96–2.35 Å. In the second Li1+ site, Li1+ is bonded to four O2- atoms to form distorted LiO4 tetrahedra that share corners with four PO4 tetrahedra and an edgeedge with one VO6 octahedra. There are a spread of Li–O bond distances ranging from 1.97–2.11 Å. In the third Li1+ site, Li1+ is bonded in a 4-coordinate geometry to four O2- atoms. There are a spread of Li–O bond distances ranging from 1.97–2.25 Å. In the fourth Li1+ site, Li1+ is bonded in a 5-coordinate geometry to five O2- atoms. There are a spread of Li–O bond distances ranging from 1.94–2.52 Å. In the fifth Li1+ site, Li1+ is bonded in a 5-coordinate geometry to five O2- atoms. There are a spread of Li–O bond distances ranging from 1.94–2.60 Å. In the sixth Li1+ site, Li1+ is bonded in a 4-coordinate geometry to four O2- atoms. There are a spread of Li–O bond distances ranging from 1.96–2.35 Å. In the seventh Li1+ site, Li1+ is bonded in a 3-coordinate geometry to four O2- atoms. There are a spread of Li–O bond distances ranging from 1.93–2.60 Å. In the eighth Li1+ site, Li1+ is bonded in a 5-coordinate geometry to five O2- atoms. There are a spread of Li–O bond distances ranging from 1.97–2.79 Å. There are six inequivalent V+4.67+ sites. In the first V+4.67+ site, V+4.67+ is bonded to six O2- atoms to form VO6 octahedra that share corners with six PO4 tetrahedra. There are a spread of V–O bond distances ranging from 1.81–1.96 Å. In the second V+4.67+ site, V+4.67+ is bonded to six O2- atoms to form VO6 octahedra that share corners with six PO4 tetrahedra. There are a spread of V–O bond distances ranging from 1.83–1.93 Å. In the third V+4.67+ site, V+4.67+ is bonded to six O2- atoms to form VO6 octahedra that share corners with six PO4 tetrahedra. There are a spread of V–O bond distances ranging from 1.84–1.92 Å. In the fourth V+4.67+ site, V+4.67+ is bonded to six O2- atoms to form VO6 octahedra that share corners with six PO4 tetrahedra and an edgeedge with one LiO4 tetrahedra. There are a spread of V–O bond distances ranging from 1.87–2.00 Å. In the fifth V+4.67+ site, V+4.67+ is bonded to six O2- atoms to form VO6 octahedra that share corners with six PO4 tetrahedra. There are a spread of V–O bond distances ranging from 1.85–1.91 Å. In the sixth V+4.67+ site, V+4.67+ is bonded to six O2- atoms to form VO6 octahedra that share corners with six PO4 tetrahedra. There are a spread of V–O bond distances ranging from 1.86–2.02 Å. There are sixteen inequivalent P5+ sites. In the first P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two VO6 octahedra and a cornercorner with one PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 39–41°. There are a spread of P–O bond distances ranging from 1.48–1.62 Å. In the second P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two VO6 octahedra and a cornercorner with one PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 39–40°. There are a spread of P–O bond distances ranging from 1.50–1.63 Å. In the third P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two VO6 octahedra and a cornercorner with one PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 37–44°. There are a spread of P–O bond distances ranging from 1.49–1.61 Å. In the fourth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with three VO6 octahedra and a cornercorner with one LiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 28–37°. There are a spread of P–O bond distances ranging from 1.48–1.60 Å. In the fifth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with three VO6 octahedra. The corner-sharing octahedra tilt angles range from 32–38°. There are a spread of P–O bond distances ranging from 1.49–1.59 Å. In the sixth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two VO6 octahedra and a cornercorner with one PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 37–44°. There are a spread of P–O bond distances ranging from 1.49–1.62 Å. In the seventh P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two VO6 octahedra and a cornercorner with one PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 37–39°. There are a spread of P–O bond distances ranging from 1.50–1.61 Å. In the eighth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two VO6 octahedra, a cornercorner with one LiO4 tetrahedra, and a cornercorner with one PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 38–39°. There are a spread of P–O bond distances ranging from 1.50–1.60 Å. In the ninth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two VO6 octahedra and a cornercorner with one PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 35–38°. There are a spread of P–O bond distances ranging from 1.50–1.60 Å. In the tenth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two VO6 octahedra and a cornercorner with one PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 35–37°. There are a spread of P–O bond distances ranging from 1.50–1.61 Å. In the eleventh P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two VO6 octahedra, a cornercorner with one LiO4 tetrahedra, and a cornercorner with one PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 37–44°. There are a spread of P–O bond distances ranging from 1.50–1.61 Å. In the twelfth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with three VO6 octahedra. The corner-sharing octahedra tilt angles range from 32–35°. There are a spread of P–O bond distances ranging from 1.49–1.59 Å. In the thirteenth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with three VO6 octahedra. The corner-sharing octahedra tilt angles range from 32–37°. There are a spread of P–O bond distances ranging from 1.49–1.60 Å. In the fourteenth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two VO6 octahedra and a cornercorner with one PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 37–42°. There are a spread of P–O bond distances ranging from 1.48–1.60 Å. In the fifteenth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two VO6 octahedra and a cornercorner with one PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 36–45°. There are a spread of P–O bond distances ranging from 1.49–1.63 Å. In the sixteenth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two VO6 octahedra, a cornercorner with one LiO4 tetrahedra, and a cornercorner with one PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 36–44°. There are a spread of P–O bond distances ranging from 1.50–1.63 Å. There are fifty-eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 150 degrees geometry to one Li1+ and one P5+ atom. In the second O2- site, O2- is bonded in a bent 150 degrees geometry to one V+4.67+ and one P5+ atom. In the third O2- site, O2- is bonded in a distorted trigonal planar geometry to two Li1+ and one P5+ atom. In the fourth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Li1+, one V+4.67+, and one P5+ atom. In the fifth O2- site, O2- is bonded in a bent 150 degrees geometry to one V+4.67+ and one P5+ atom. In the sixth O2- site, O2- is bonded in a bent 150 degrees geometry to one V+4.67+ and one P5+ atom. In the seventh O2- site, O2- is bonded in a bent 150 degrees geometry to one V+4.67+ and one P5+ atom. In the eighth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Li1+ and one P5+ atom. In the ninth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Li1+, one V+4.67+, and one P5+ atom. In the tenth O2- site, O2- is bonded in a bent 150 degrees geometry to one V+4.67+ and one P5+ atom. In the eleventh O2- site, O2- is bonded in a bent 150 degrees geometry to one V+4.67+ and one P5+ atom. In the twelfth O2- site, O2- is bonded in a 3-coordinate geometry to one Li1+, one V+4.67+, and one P5+ atom. In the thirteenth O2- site, O2- is bonded in a single-bond geometry to one P5+ atom. In the fourteenth O2- site, O2- is bonded in a distorted L-shaped geometry to one Li1+ and one P5+ atom. In the fifteenth O2- site, O2- is bonded in a bent 150 degrees geometry to one V+4.67+ and one P5+ atom. In the sixteenth O2- site, O2- is bonded in a bent 150 degrees geometry to one V+4.67+ and one P5+ atom. In the seventeenth O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to one Li1+, one V+4.67+, and one P5+ atom. In the eighteenth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Li1+, one V+4.67+, and one P5+ atom. In the nineteenth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two P5+ atoms. In the twentieth O2- site, O2- is bonded in a trigonal planar geometry to two Li1+ and one P5+ atom. In the twenty-first O2- site, O2- is bonded in a 2-coordinate geometry to two Li1+ and one P5+ atom. In the twenty-second O2- site, O2- is bonded in a bent 150 degrees geometry to one V+4.67+ and one P5+ atom. In the twenty-third O2- site, O2- is bonded in a distorted T-shaped geometry to one Li1+, one V+4.67+, and one P5+ atom. In the twenty-fourth O2- site, O2- is bonded in a bent 150 degrees geometry to one V+4.67+ and one P5+ atom. In the twenty-fifth O2- site, O2- is bonded in a bent 150 degrees geometry to one V+4.67+ and one P5+ atom. In the twenty-sixth O2- site, O2- is bonded in a bent 150 degrees geometry to one V+4.67+ and one P5+ atom. In the twenty-seventh O2- site, O2- is bonded in a bent 120 degrees geometry to two P5+ atoms. In the twenty-eighth O2- site, O2- is bonded in a trigonal planar geometry to two Li1+ and one P5+ atom. In the twenty-ninth O2- site, O2- is bonded in a 2-coordinate geometry to two Li1+ and one P5+ atom. In the thirtieth O2- site, O2- is bonded in a bent 150 degrees geometry to one V+4.67+ and one P5+ atom. In the thirty-first O2- site, O2- is bonded in a bent 150 degrees geometry to one V+4.67+ and one P5+ atom. In the thirty-second O2- site, O2- is bonded in a bent 150 degrees geometry to one V+4.67+ and one P5+ atom. In the thirty-third O2- site, O2- is bonded in a 3-coordinate geometry to one Li1+, one V+4.67+, and one P5+ atom. In the thirty-fourth O2- site, O2- is bonded in a bent 150 degrees geometry to one V+4.67+ and one P5+ atom. In the thirty-fifth O2- site, O2- is bonded in a trigonal planar geometry to two Li1+ and one P5+ atom. In the thirty-sixth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Li1+ and one P5+ atom. In the thirty-seventh O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two P5+ atoms. In the thirty-eighth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Li1+, one V+4.67+, and one P5+ atom. In the thirty-ninth O2- site, O2- is bonded in a 3-coordinate geometry to one Li1+, one V+4.67+, and one P5+ atom. In the fortieth O2- site, O2- is bonded in a bent 150 degrees geometry to one V+4.67+ and one P5+ atom. In the forty-first O2- site, O2- is bonded in a bent 150 degrees geometry to one V+4.67+ and one P5+ atom. In the forty-second O2- site, O2- is bonded in a distorted single-bond geom

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on NF by Materials Project

NF is Wurtzite structured and crystallizes in the orthorhombic Cmc2_1 space group. The structure is zero-dimensional and consists of four monofluoroamine molecules. N1+ is bonded in a single-bond geometry to one F1- atom. The N–F bond length is 1.33 Å. F1- is bonded in a single-bond geometry to one N1+ atom.

36 MATERIALS SCIENCE↗