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All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on Mg(CuO2)2 by Materials Project

MgCu2O4 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are four inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Mg–O bond distances ranging from 2.19–2.38 Å. In the second Mg2+ site, Mg2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Mg–O bond distances ranging from 2.18–2.42 Å. In the third Mg2+ site, Mg2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Mg–O bond distances ranging from 2.19–2.43 Å. In the fourth Mg2+ site, Mg2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Mg–O bond distances ranging from 2.20–2.40 Å. There are eight inequivalent Cu3+ sites. In the first Cu3+ site, Cu3+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing CuO6 octahedra. The corner-sharing octahedra tilt angles range from 48–63°. There are a spread of Cu–O bond distances ranging from 1.94–2.06 Å. In the second Cu3+ site, Cu3+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing CuO6 octahedra. The corner-sharing octahedra tilt angles range from 48–62°. There are a spread of Cu–O bond distances ranging from 1.94–2.05 Å. In the third Cu3+ site, Cu3+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing CuO6 octahedra. The corner-sharing octahedra tilt angles range from 48–63°. There are a spread of Cu–O bond distances ranging from 1.94–2.06 Å. In the fourth Cu3+ site, Cu3+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing CuO6 octahedra. The corner-sharing octahedra tilt angles range from 48–64°. There are a spread of Cu–O bond distances ranging from 1.94–2.06 Å. In the fifth Cu3+ site, Cu3+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing CuO6 octahedra. The corner-sharing octahedra tilt angles range from 48–63°. There are a spread of Cu–O bond distances ranging from 1.89–2.07 Å. In the sixth Cu3+ site, Cu3+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing CuO6 octahedra. The corner-sharing octahedra tilt angles range from 48–62°. There are a spread of Cu–O bond distances ranging from 1.89–2.06 Å. In the seventh Cu3+ site, Cu3+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing CuO6 octahedra. The corner-sharing octahedra tilt angles range from 48–63°. There are a spread of Cu–O bond distances ranging from 1.89–2.06 Å. In the eighth Cu3+ site, Cu3+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing CuO6 octahedra. The corner-sharing octahedra tilt angles range from 48–64°. There are a spread of Cu–O bond distances ranging from 1.90–2.07 Å. There are sixteen inequivalent O2- sites. In the first O2- site, O2- is bonded to two equivalent Mg2+ and three Cu3+ atoms to form a mixture of distorted edge and corner-sharing OMg2Cu3 trigonal bipyramids. In the second O2- site, O2- is bonded to two equivalent Mg2+ and three Cu3+ atoms to form a mixture of distorted edge and corner-sharing OMg2Cu3 trigonal bipyramids. In the third O2- site, O2- is bonded to two equivalent Mg2+ and three Cu3+ atoms to form a mixture of distorted edge and corner-sharing OMg2Cu3 trigonal bipyramids. In the fourth O2- site, O2- is bonded to two equivalent Mg2+ and three Cu3+ atoms to form a mixture of distorted edge and corner-sharing OMg2Cu3 trigonal bipyramids. In the fifth O2- site, O2- is bonded in a 5-coordinate geometry to two Mg2+ and three Cu3+ atoms. In the sixth O2- site, O2- is bonded to two Mg2+ and three Cu3+ atoms to form a mixture of distorted edge and corner-sharing OMg2Cu3 trigonal bipyramids. In the seventh O2- site, O2- is bonded in a 5-coordinate geometry to two Mg2+ and three Cu3+ atoms. In the eighth O2- site, O2- is bonded in a 5-coordinate geometry to two Mg2+ and three Cu3+ atoms. In the ninth O2- site, O2- is bonded to two equivalent Mg2+ and three Cu3+ atoms to form a mixture of distorted edge and corner-sharing OMg2Cu3 square pyramids. In the tenth O2- site, O2- is bonded to two equivalent Mg2+ and three Cu3+ atoms to form a mixture of distorted edge and corner-sharing OMg2Cu3 square pyramids. In the eleventh O2- site, O2- is bonded to two equivalent Mg2+ and three Cu3+ atoms to form a mixture of distorted edge and corner-sharing OMg2Cu3 square pyramids. In the twelfth O2- site, O2- is bonded to two equivalent Mg2+ and three Cu3+ atoms to form a mixture of distorted edge and corner-sharing OMg2Cu3 square pyramids. In the thirteenth O2- site, O2- is bonded in a 5-coordinate geometry to two equivalent Mg2+ and three Cu3+ atoms. In the fourteenth O2- site, O2- is bonded in a 5-coordinate geometry to two equivalent Mg2+ and three Cu3+ atoms. In the fifteenth O2- site, O2- is bonded in a 5-coordinate geometry to two equivalent Mg2+ and three Cu3+ atoms. In the sixteenth O2- site, O2- is bonded in a 5-coordinate geometry to two equivalent Mg2+ and three Cu3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mg(C2O3)2 by Materials Project

Mg(CO3)2(C)2 crystallizes in the monoclinic C2/c space group. The structure is two-dimensional and consists of four ethyne molecules and two Mg(CO3)2 sheets oriented in the (1, 0, 0) direction. In each Mg(CO3)2 sheet, Mg2+ is bonded in an octahedral geometry to six O2- atoms. There are a spread of Mg–O bond distances ranging from 2.04–2.16 Å. C+2.50+ is bonded in a bent 120 degrees geometry to two O2- atoms. There is one shorter (1.25 Å) and one longer (1.29 Å) C–O bond length. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Mg2+ and one C+2.50+ atom. In the second O2- site, O2- is bonded in a bent 120 degrees geometry to one Mg2+ and one C+2.50+ atom. In the third O2- site, O2- is bonded in a single-bond geometry to one Mg2+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mg(BH4)2 by Materials Project

Mg(BH4)2 crystallizes in the tetragonal I4_1/amd space group. The structure is three-dimensional and consists of two Mg(BH4)2 frameworks. there are two inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded to eight H+0.50+ atoms to form MgH8 hexagonal bipyramids that share edges with four equivalent BH4 tetrahedra. There are four shorter (2.07 Å) and four longer (2.12 Å) Mg–H bond lengths. In the second Mg2+ site, Mg2+ is bonded in a body-centered cubic geometry to eight equivalent H+0.50+ atoms. All Mg–H bond lengths are 2.11 Å. B3- is bonded to four H+0.50+ atoms to form BH4 tetrahedra that share an edgeedge with one MgH8 hexagonal bipyramid. There is three shorter (1.22 Å) and one longer (1.23 Å) B–H bond length. There are three inequivalent H+0.50+ sites. In the first H+0.50+ site, H+0.50+ is bonded in a distorted L-shaped geometry to one Mg2+ and one B3- atom. In the second H+0.50+ site, H+0.50+ is bonded in an L-shaped geometry to one Mg2+ and one B3- atom. In the third H+0.50+ site, H+0.50+ is bonded in a distorted L-shaped geometry to one Mg2+ and one B3- atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mg(BH4)2 by Materials Project

Mg(BH4)2 crystallizes in the orthorhombic Fddd space group. The structure is three-dimensional and consists of two Mg(BH4)2 frameworks. there are two inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded to eight H+0.50+ atoms to form MgH8 hexagonal bipyramids that share edges with four equivalent BH4 tetrahedra. There are four shorter (2.08 Å) and four longer (2.12 Å) Mg–H bond lengths. In the second Mg2+ site, Mg2+ is bonded to eight H+0.50+ atoms to form distorted MgH8 hexagonal bipyramids that share edges with four equivalent BH4 tetrahedra. There are four shorter (2.09 Å) and four longer (2.12 Å) Mg–H bond lengths. B3- is bonded to four H+0.50+ atoms to form BH4 tetrahedra that share edges with two MgH8 hexagonal bipyramids. There is two shorter (1.22 Å) and two longer (1.23 Å) B–H bond length. There are four inequivalent H+0.50+ sites. In the first H+0.50+ site, H+0.50+ is bonded in a distorted L-shaped geometry to one Mg2+ and one B3- atom. In the second H+0.50+ site, H+0.50+ is bonded in an L-shaped geometry to one Mg2+ and one B3- atom. In the third H+0.50+ site, H+0.50+ is bonded in a distorted L-shaped geometry to one Mg2+ and one B3- atom. In the fourth H+0.50+ site, H+0.50+ is bonded in an L-shaped geometry to one Mg2+ and one B3- atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mg(AlSn)2 by Materials Project

Mg(AlSn)2 crystallizes in the trigonal P-3m1 space group. The structure is three-dimensional. Mg is bonded to six equivalent Sn atoms to form MgSn6 octahedra that share corners with twelve equivalent AlSn4 tetrahedra, edges with six equivalent MgSn6 octahedra, and edges with six equivalent AlSn4 tetrahedra. All Mg–Sn bond lengths are 3.08 Å. Al is bonded to four equivalent Sn atoms to form AlSn4 tetrahedra that share corners with six equivalent MgSn6 octahedra, corners with six equivalent AlSn4 tetrahedra, edges with three equivalent MgSn6 octahedra, and edges with three equivalent AlSn4 tetrahedra. The corner-sharing octahedra tilt angles range from 11–57°. There are three shorter (2.78 Å) and one longer (2.85 Å) Al–Sn bond lengths. Sn is bonded to three equivalent Mg and four equivalent Al atoms to form a mixture of distorted edge and corner-sharing SnMg3Al4 pentagonal bipyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mg(Hg11N3)2 by Materials Project

Mg(Hg11N3)2 crystallizes in the tetragonal I4/m space group. The structure is three-dimensional. Mg is bonded in a square co-planar geometry to four equivalent N atoms. All Mg–N bond lengths are 2.25 Å. There are five inequivalent Hg sites. In the first Hg site, Hg is bonded in a single-bond geometry to one Hg and one N atom. The Hg–Hg bond length is 2.79 Å. The Hg–N bond length is 2.22 Å. In the second Hg site, Hg is bonded in a single-bond geometry to one Hg and one N atom. The Hg–Hg bond length is 2.94 Å. The Hg–N bond length is 2.23 Å. In the third Hg site, Hg is bonded in a single-bond geometry to one Hg and one N atom. The Hg–Hg bond length is 3.11 Å. The Hg–N bond length is 2.48 Å. In the fourth Hg site, Hg is bonded to six Hg atoms to form HgHg6 octahedra that share a cornercorner with one NHg5 square pyramid. The Hg–Hg bond length is 2.90 Å. In the fifth Hg site, Hg is bonded to four equivalent Hg atoms to form distorted HgHg4 tetrahedra that share corners with four equivalent NHg5 square pyramids. There are two inequivalent N sites. In the first N site, N is bonded to five Hg atoms to form distorted NHg5 square pyramids that share a cornercorner with one HgHg6 octahedra and corners with four equivalent HgHg4 tetrahedra. The corner-sharing octahedral tilt angles are 0°. In the second N site, N is bonded in a distorted T-shaped geometry to one Mg and two equivalent Hg atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mg(MnSn)6 by Materials Project

MgMn6Sn6 crystallizes in the hexagonal P6/mmm space group. The structure is three-dimensional. Mg is bonded to eight Sn atoms to form edge-sharing MgSn8 hexagonal bipyramids. There are two shorter (2.93 Å) and six longer (3.14 Å) Mg–Sn bond lengths. Mn is bonded in a 12-coordinate geometry to six Sn atoms. There are a spread of Mn–Sn bond distances ranging from 2.74–2.81 Å. There are three inequivalent Sn sites. In the first Sn site, Sn is bonded in a 7-coordinate geometry to one Mg and six equivalent Mn atoms. In the second Sn site, Sn is bonded in a 12-coordinate geometry to three equivalent Mg and six equivalent Mn atoms. In the third Sn site, Sn is bonded in a 6-coordinate geometry to six equivalent Mn atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mg(Hg11N3)2 by Materials Project

Mg(Hg11N3)2 crystallizes in the tetragonal I4/m space group. The structure is three-dimensional. Mg is bonded in a square co-planar geometry to four equivalent N atoms. All Mg–N bond lengths are 2.13 Å. There are five inequivalent Hg sites. In the first Hg site, Hg is bonded in a single-bond geometry to one Hg and one N atom. The Hg–Hg bond length is 2.71 Å. The Hg–N bond length is 2.20 Å. In the second Hg site, Hg is bonded in a single-bond geometry to one Hg and one N atom. The Hg–Hg bond length is 2.98 Å. The Hg–N bond length is 2.14 Å. In the third Hg site, Hg is bonded in a single-bond geometry to two Hg and one N atom. There are one shorter (3.10 Å) and one longer (3.27 Å) Hg–Hg bond lengths. The Hg–N bond length is 2.46 Å. In the fourth Hg site, Hg is bonded in a 9-coordinate geometry to nine Hg atoms. In the fifth Hg site, Hg is bonded in a 4-coordinate geometry to four equivalent Hg atoms. There are two inequivalent N sites. In the first N site, N is bonded in a distorted trigonal bipyramidal geometry to five Hg atoms. In the second N site, N is bonded in a trigonal planar geometry to one Mg and two equivalent Hg atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mg(ScS2)2 by Materials Project

Mg(ScS2)2 crystallizes in the triclinic P-1 space group. The structure is two-dimensional and consists of one Mg(ScS2)2 sheet oriented in the (0, 0, 1) direction. there are two inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded to four S2- atoms to form MgS4 tetrahedra that share a cornercorner with one MgS6 octahedra, corners with two equivalent ScS6 octahedra, and corners with six ScS4 tetrahedra. The corner-sharing octahedra tilt angles range from 59–61°. There are one shorter (2.43 Å) and three longer (2.46 Å) Mg–S bond lengths. In the second Mg2+ site, Mg2+ is bonded to six S2- atoms to form MgS6 octahedra that share a cornercorner with one MgS4 tetrahedra, corners with five ScS4 tetrahedra, edges with two equivalent MgS6 octahedra, and edges with four equivalent ScS6 octahedra. There are a spread of Mg–S bond distances ranging from 2.64–2.70 Å. There are four inequivalent Sc3+ sites. In the first Sc3+ site, Sc3+ is bonded to four S2- atoms to form ScS4 tetrahedra that share a cornercorner with one ScS6 octahedra, corners with two equivalent MgS6 octahedra, corners with two equivalent MgS4 tetrahedra, and corners with four ScS4 tetrahedra. The corner-sharing octahedra tilt angles range from 59–61°. There are a spread of Sc–S bond distances ranging from 2.42–2.47 Å. In the second Sc3+ site, Sc3+ is bonded to six S2- atoms to form ScS6 octahedra that share corners with two equivalent MgS4 tetrahedra, corners with four ScS4 tetrahedra, edges with two equivalent ScS6 octahedra, and edges with four equivalent MgS6 octahedra. There are a spread of Sc–S bond distances ranging from 2.58–2.68 Å. In the third Sc3+ site, Sc3+ is bonded to four S2- atoms to form ScS4 tetrahedra that share a cornercorner with one ScS6 octahedra, corners with two equivalent MgS6 octahedra, corners with two equivalent MgS4 tetrahedra, and corners with four ScS4 tetrahedra. The corner-sharing octahedra tilt angles range from 59–61°. There are a spread of Sc–S bond distances ranging from 2.42–2.48 Å. In the fourth Sc3+ site, Sc3+ is bonded to four S2- atoms to form ScS4 tetrahedra that share a cornercorner with one MgS6 octahedra, corners with two equivalent ScS6 octahedra, corners with two equivalent MgS4 tetrahedra, and corners with four ScS4 tetrahedra. The corner-sharing octahedral tilt angles are 60°. There are a spread of Sc–S bond distances ranging from 2.43–2.47 Å. There are eight inequivalent S2- sites. In the first S2- site, S2- is bonded to two equivalent Mg2+ and two Sc3+ atoms to form distorted SMg2Sc2 trigonal pyramids that share corners with five SMg2Sc2 tetrahedra, corners with four equivalent SMgSc3 trigonal pyramids, edges with two SMg2Sc2 tetrahedra, and an edgeedge with one SMg2Sc2 trigonal pyramid. In the second S2- site, S2- is bonded to two Mg2+ and two equivalent Sc3+ atoms to form distorted SMg2Sc2 tetrahedra that share corners with four equivalent SMg2Sc2 tetrahedra, corners with five SMg2Sc2 trigonal pyramids, an edgeedge with one SMg2Sc2 tetrahedra, and edges with two SMgSc3 trigonal pyramids. In the third S2- site, S2- is bonded in a trigonal non-coplanar geometry to one Mg2+ and two Sc3+ atoms. In the fourth S2- site, S2- is bonded in a trigonal non-coplanar geometry to three Sc3+ atoms. In the fifth S2- site, S2- is bonded in a trigonal non-coplanar geometry to one Mg2+ and two Sc3+ atoms. In the sixth S2- site, S2- is bonded in a trigonal non-coplanar geometry to one Mg2+ and two Sc3+ atoms. In the seventh S2- site, S2- is bonded to one Mg2+ and three Sc3+ atoms to form distorted SMgSc3 trigonal pyramids that share corners with five SMg2Sc2 tetrahedra, corners with four equivalent SMg2Sc2 trigonal pyramids, edges with two SMg2Sc2 tetrahedra, and an edgeedge with one SMgSc3 trigonal pyramid. In the eighth S2- site, S2- is bonded to two equivalent Mg2+ and two Sc3+ atoms to form distorted SMg2Sc2 tetrahedra that share corners with four equivalent SMg2Sc2 tetrahedra, corners with five SMg2Sc2 trigonal pyramids, an edgeedge with one SMg2Sc2 tetrahedra, and edges with two SMgSc3 trigonal pyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mg(AlSb)2 by Materials Project

Mg(AlSb)2 crystallizes in the trigonal P-3m1 space group. The structure is three-dimensional. Mg is bonded to six equivalent Sb atoms to form MgSb6 octahedra that share corners with twelve equivalent AlSb4 tetrahedra, edges with six equivalent MgSb6 octahedra, and edges with six equivalent AlSb4 tetrahedra. All Mg–Sb bond lengths are 3.12 Å. Al is bonded to four equivalent Sb atoms to form AlSb4 tetrahedra that share corners with six equivalent MgSb6 octahedra, corners with six equivalent AlSb4 tetrahedra, edges with three equivalent MgSb6 octahedra, and edges with three equivalent AlSb4 tetrahedra. The corner-sharing octahedra tilt angles range from 11–58°. There are one shorter (2.83 Å) and three longer (2.84 Å) Al–Sb bond lengths. Sb is bonded to three equivalent Mg and four equivalent Al atoms to form a mixture of distorted edge and corner-sharing SbMg3Al4 pentagonal bipyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mg(BH4)2 by Materials Project

Mg(BH4)2 crystallizes in the cubic Fd-3m space group. The structure is three-dimensional and consists of two Mg(BH4)2 frameworks. there are two inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded to twelve equivalent H+0.50+ atoms to form distorted MgH12 cuboctahedra that share faces with four equivalent BH4 tetrahedra. All Mg–H bond lengths are 2.30 Å. In the second Mg2+ site, Mg2+ is bonded to four equivalent H+0.50+ atoms to form MgH4 tetrahedra that share corners with four equivalent BH4 tetrahedra. All Mg–H bond lengths are 1.80 Å. B3- is bonded to four H+0.50+ atoms to form BH4 tetrahedra that share a cornercorner with one MgH4 tetrahedra and a faceface with one MgH12 cuboctahedra. There is three shorter (1.22 Å) and one longer (1.24 Å) B–H bond length. There are two inequivalent H+0.50+ sites. In the first H+0.50+ site, H+0.50+ is bonded in a linear geometry to one Mg2+ and one B3- atom. In the second H+0.50+ site, H+0.50+ is bonded in a single-bond geometry to one Mg2+ and one B3- atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mg(IN)2 by Materials Project

Mg(NI)2 crystallizes in the orthorhombic Pbam space group. The structure is one-dimensional and consists of two Mg(NI)2 ribbons oriented in the (1, 0, 0) direction. Mg2+ is bonded to two equivalent N and four equivalent I1- atoms to form edge-sharing MgI4N2 octahedra. Both Mg–N bond lengths are 2.25 Å. All Mg–I bond lengths are 2.86 Å. N is bonded in a single-bond geometry to one Mg2+ atom. I1- is bonded in an L-shaped geometry to two equivalent Mg2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Experimental characterization and atomistic simulation of grain boundary segregation in Mg-Y alloys

As a rare earth solute element in Mg alloys, Y has the beneficial effects of increasing both the strength and the ductility as well as weakening the crystallographic texture. To achieve a more fundamental understanding on how Y addition affects the microstructural evolution and mechanical properties, the Y segregation behavior at grain boundaries was investigated in Mg-1wt.%Y and Mg-7wt.%Y alloys at different conditions. The segregation intensity and its dependence on the grain boundary misorientation angle were experimentally characterized and computationally predicted. Strong segregation at grain boundaries was observed in both low and high Y-containing alloys. Y segregation was found to remain in alloy Mg-7Y after high-temperature annealing heat treatment at 540 °C. No direct correlation between the Y segregation intensity and the grain boundary misorientation angle could be established based on either the experimental characterization or the atomistic simulation with a spectral model. We thus conclude that grain boundary segregation of Y is independent of grain boundary misorientation angle.

Grain boundary↗
DOE OSTI2025

Effect of Mg and Ni impurities on tritium diffusion in lithium ceramics through cluster dynamics simulations

This study investigates the impact of Mg and Ni doping on tritium diffusion in LiAlO 2 and LiAl 5 O 8 ceramics, that are used in tritium-producing burnable absorber rods (TPBARs). Utilizing Centipede simulations across a broad temperature range (500 K to 1250 K), we explore the interplay between defect dynamics, cluster formation, and tritium mobility. In LiAlO 2 , Mg doping significantly enhances tritium diffusivity by increasing tritium interstitial concentrations and diffusion coefficients of key species, thereby doubling the overall tritium diffusivity. Ni doping, while shifting the dominant defect to Li vacancies, maintains high tritium mobility due to the low binding energy of Li vacancy-tritium complexes, which ensures effective tritium migration. In LiAl 5 O 8 , Mg and Ni doping results in a slight reduction in the diffusion coefficients of key species, yet the dramatic increase in tritium interstitial concentrations compensates, leading to a net small increase in tritium diffusivity. In conclusion, the findings highlight the critical role of defects in tritium transport and the effect of Mg and Ni defects on the performance of these ceramics in demanding nuclear environments.

Cluster dynamics↗
DOE OSTI2024

Coexistence and Interplay of Two Ferroelectric Mechanisms in Zn 1-x Mg x O

Ferroelectric materials promise exceptional attributes including low power dissipation, fast operational speeds, enhanced endurance, and superior retention to revolutionize information technology. However, the practical application of ferroelectric-semiconductor memory devices has been significantly challenged by the incompatibility of traditional perovskite oxide ferroelectrics with metal-oxide-semiconductor technology. Recent discoveries of ferroelectricity in binary oxides such as Zn 1-x Mg x O and Hf 1-x Zr x O have been a focal point of research in ferroelectric information technology. Here, this work investigates the ferroelectric properties of Zn 1-x Mg x O utilizing automated band excitation piezoresponse force microscopy. This findings reveal the coexistence of two ferroelectric subsystems within Zn 1-x Mg x O. A “fringing-ridge mechanism” of polarization switching is proposed that is characterized by initial lateral expansion of nucleation without significant propagation in depth, contradicting the conventional domain growth process observed in ferroelectrics. This unique polarization dynamics in Zn 1-x Mg x O suggests a new understanding of ferroelectric behavior, contributing to both the fundamental science of ferroelectrics and their application in information technology.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Polarity‐Driven Atomic Displacements at the 2D Mg 2 TiO 4 ‐MgO (001) Oxide Interface for Hosting Potential Interlayer Excitons

Abstract Interlayer excitons in solid‐state systems have emerged as candidates for realizing novel platforms ranging from excitonic transistors and optical qubits to exciton condensates. Interlayer excitons have been discovered in 2D transition metal dichalcogenides, with large exciton binding energies and the ability to form various van der Waals heterostructures. Here, an oxide system consisting of a single unit cell of Mg 2 TiO 4 on MgO (001) is proposed as a platform for hosting interlayer excitons. Using a combination of density functional theory (DFT) calculations, molecular beam epitaxy growth, and in situ crystal truncation rod measurements, it is shown that the Mg 2 TiO 4 ‐MgO interface can be precisely controlled to yield an internal electric field suitable for hosting interlayer excitons. The atoms in the polar Mg 2 TiO 4 layers are observed to be displaced to reduce polarity at the interface with the non‐polar MgO (001) surface. Such polarity‐driven atomic displacements strongly affect electrostatics of the film and the interface, resulting in localization of filled and empty band‐edge states in different layers of the Mg 2 TiO 4 film. The DFT calculations suggest that the electronic structure is favorable for localization of photoexcited electrons in the bottom layer and holes in the top layer, which may bind to form interlayer exciton states.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Fast Room-Temperature Mg-Ion Conduction in Clay-Like Halide Glassy Electrolytes

The discovery of mechanically soft solid-state materials with fast Mg-ion conduction is crucial for the development of solid-state magnesium batteries. In this paper, novel magnesium gallium halide compounds are reported that achieve high ionic conductivity of 0.47 mS cm -1 at room temperature. These Mg-ion conductors obtained by ball milling Mg and Ga salts exhibit clay-like mechanical properties, enabling intimate contact at the electrode–electrolyte interface during battery cycling. With a combination of experimental and computational analysis, this study identifies that the soft-clay formation is induced by partial anion exchange during milling. This partial anion exchange creates undercoordinated magnesium ions in a chlorine-rich environment, yielding fast Mg-ion conduction. This work demonstrates the potential of clay-like halide electrolytes for all-solid-state magnesium batteries, with possible further extension to other multivalent battery systems.

36 MATERIALS SCIENCE↗
DOE OSTI2026

Improvement of Drop‐Hammer Impact Testing for Safety Assessment of High Explosives Using 10‐mg Samples

Here, in this study, we established an improved method for drop-hammer impact testing of small quantities of high explosives (10 mg). We performed about seven hundred impact tests under various experimental conditions (e.g., sandpaper vs bare anvil, different sample masses, drop-weights, and striker diameters) to determine an optimal set of conditions and reaction detection methods (e.g., gas analysis, video, and sound recordings) that give the most statistically reliable results with 10 mg samples. We used both Frequentist and Bayesian statistical approaches to compare estimates of the drop height (DH50) that initiates a reaction 50% of the time, and to quantify the associated uncertainty. Gas analysis proved to be the most reliable reaction detection method, showing unambiguous rises in HE decomposition products (e.g., CO 2 ) even when the other indicators (e.g., sound, video) were inconclusive. The impact tests performed with a bare anvil showed much better reproducibility than those conducted with sandpaper, reducing the largest uncertainty observed in the data sets by a factor of 1.7. The DH 50 values obtained from three different sample masses (10, 20, and 35 mg) fell within the uncertainties of the measurements. We demonstrated the improved procedure (i.e., 10-mg samples, gas analysis, bare anvil, and Bayesian approach) on a variety of PETN samples having different surface areas and thermal histories.

PETN↗