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8 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on MgB4(H10N)2 by Materials Project

MgB4(NH10)2 crystallizes in the orthorhombic P2_12_12_1 space group. The structure is zero-dimensional and consists of four MgB4(NH10)2 clusters. Mg2+ is bonded to eight H+0.80+ atoms to form distorted MgH8 hexagonal bipyramids that share edges with four BH4 tetrahedra. There are a spread of Mg–H bond distances ranging from 1.97–2.11 Å. There are four inequivalent B3- sites. In the first B3- site, B3- is bonded to four H+0.80+ atoms to form BH4 tetrahedra that share an edgeedge with one MgH8 hexagonal bipyramid. There is two shorter (1.22 Å) and two longer (1.24 Å) B–H bond length. In the second B3- site, B3- is bonded to four H+0.80+ atoms to form BH4 tetrahedra that share an edgeedge with one MgH8 hexagonal bipyramid. There are a spread of B–H bond distances ranging from 1.21–1.25 Å. In the third B3- site, B3- is bonded to one N3- and three H+0.80+ atoms to form BH3N tetrahedra that share an edgeedge with one MgH8 hexagonal bipyramid. The B–N bond length is 1.58 Å. There is one shorter (1.21 Å) and two longer (1.23 Å) B–H bond length. In the fourth B3- site, B3- is bonded to one N3- and three H+0.80+ atoms to form BH3N tetrahedra that share an edgeedge with one MgH8 hexagonal bipyramid. The B–N bond length is 1.59 Å. There is one shorter (1.21 Å) and two longer (1.23 Å) B–H bond length. There are two inequivalent N3- sites. In the first N3- site, N3- is bonded in a tetrahedral geometry to one B3- and three H+0.80+ atoms. All N–H bond lengths are 1.03 Å. In the second N3- site, N3- is bonded in a tetrahedral geometry to one B3- and three H+0.80+ atoms. All N–H bond lengths are 1.03 Å. There are twenty inequivalent H+0.80+ sites. In the first H+0.80+ site, H+0.80+ is bonded in a single-bond geometry to one N3- atom. In the second H+0.80+ site, H+0.80+ is bonded in a single-bond geometry to one N3- atom. In the third H+0.80+ site, H+0.80+ is bonded in a single-bond geometry to one N3- atom. In the fourth H+0.80+ site, H+0.80+ is bonded in a single-bond geometry to one N3- atom. In the fifth H+0.80+ site, H+0.80+ is bonded in a single-bond geometry to one N3- atom. In the sixth H+0.80+ site, H+0.80+ is bonded in a single-bond geometry to one N3- atom. In the seventh H+0.80+ site, H+0.80+ is bonded in an L-shaped geometry to one Mg2+ and one B3- atom. In the eighth H+0.80+ site, H+0.80+ is bonded in a single-bond geometry to one B3- atom. In the ninth H+0.80+ site, H+0.80+ is bonded in an L-shaped geometry to one Mg2+ and one B3- atom. In the tenth H+0.80+ site, H+0.80+ is bonded in a single-bond geometry to one B3- atom. In the eleventh H+0.80+ site, H+0.80+ is bonded in a single-bond geometry to one B3- atom. In the twelfth H+0.80+ site, H+0.80+ is bonded in an L-shaped geometry to one Mg2+ and one B3- atom. In the thirteenth H+0.80+ site, H+0.80+ is bonded in a single-bond geometry to one B3- atom. In the fourteenth H+0.80+ site, H+0.80+ is bonded in an L-shaped geometry to one Mg2+ and one B3- atom. In the fifteenth H+0.80+ site, H+0.80+ is bonded in an L-shaped geometry to one Mg2+ and one B3- atom. In the sixteenth H+0.80+ site, H+0.80+ is bonded in a distorted L-shaped geometry to one Mg2+ and one B3- atom. In the seventeenth H+0.80+ site, H+0.80+ is bonded in a single-bond geometry to one B3- atom. In the eighteenth H+0.80+ site, H+0.80+ is bonded in an L-shaped geometry to one Mg2+ and one B3- atom. In the nineteenth H+0.80+ site, H+0.80+ is bonded in a single-bond geometry to one B3- atom. In the twentieth H+0.80+ site, H+0.80+ is bonded in a distorted L-shaped geometry to one Mg2+ and one B3- atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on MgB4(H10N)2 by Materials Project

MgB4(NH10)2 crystallizes in the orthorhombic P2_12_12_1 space group. The structure is zero-dimensional and consists of four MgB4(NH10)2 clusters. Mg2+ is bonded to seven H+0.80+ atoms to form distorted MgH7 pentagonal bipyramids that share a cornercorner with one BH3N tetrahedra and edges with three BH4 tetrahedra. There are a spread of Mg–H bond distances ranging from 1.96–2.15 Å. There are four inequivalent B3- sites. In the first B3- site, B3- is bonded to four H+0.80+ atoms to form BH4 tetrahedra that share an edgeedge with one MgH7 pentagonal bipyramid. There are a spread of B–H bond distances ranging from 1.21–1.24 Å. In the second B3- site, B3- is bonded to four H+0.80+ atoms to form BH4 tetrahedra that share an edgeedge with one MgH7 pentagonal bipyramid. There are a spread of B–H bond distances ranging from 1.21–1.24 Å. In the third B3- site, B3- is bonded to one N3- and three H+0.80+ atoms to form BH3N tetrahedra that share a cornercorner with one MgH7 pentagonal bipyramid. The B–N bond length is 1.59 Å. There is two shorter (1.21 Å) and one longer (1.24 Å) B–H bond length. In the fourth B3- site, B3- is bonded to one N3- and three H+0.80+ atoms to form BH3N tetrahedra that share an edgeedge with one MgH7 pentagonal bipyramid. The B–N bond length is 1.59 Å. There are a spread of B–H bond distances ranging from 1.21–1.24 Å. There are two inequivalent N3- sites. In the first N3- site, N3- is bonded in a tetrahedral geometry to one B3- and three H+0.80+ atoms. All N–H bond lengths are 1.03 Å. In the second N3- site, N3- is bonded in a tetrahedral geometry to one B3- and three H+0.80+ atoms. There is one shorter (1.02 Å) and two longer (1.03 Å) N–H bond length. There are twenty inequivalent H+0.80+ sites. In the first H+0.80+ site, H+0.80+ is bonded in a single-bond geometry to one N3- atom. In the second H+0.80+ site, H+0.80+ is bonded in a single-bond geometry to one N3- atom. In the third H+0.80+ site, H+0.80+ is bonded in a single-bond geometry to one N3- atom. In the fourth H+0.80+ site, H+0.80+ is bonded in a single-bond geometry to one N3- atom. In the fifth H+0.80+ site, H+0.80+ is bonded in a single-bond geometry to one N3- atom. In the sixth H+0.80+ site, H+0.80+ is bonded in a single-bond geometry to one N3- atom. In the seventh H+0.80+ site, H+0.80+ is bonded in an L-shaped geometry to one Mg2+ and one B3- atom. In the eighth H+0.80+ site, H+0.80+ is bonded in a single-bond geometry to one B3- atom. In the ninth H+0.80+ site, H+0.80+ is bonded in an L-shaped geometry to one Mg2+ and one B3- atom. In the tenth H+0.80+ site, H+0.80+ is bonded in a single-bond geometry to one B3- atom. In the eleventh H+0.80+ site, H+0.80+ is bonded in a single-bond geometry to one B3- atom. In the twelfth H+0.80+ site, H+0.80+ is bonded in an L-shaped geometry to one Mg2+ and one B3- atom. In the thirteenth H+0.80+ site, H+0.80+ is bonded in a single-bond geometry to one B3- atom. In the fourteenth H+0.80+ site, H+0.80+ is bonded in an L-shaped geometry to one Mg2+ and one B3- atom. In the fifteenth H+0.80+ site, H+0.80+ is bonded in a bent 120 degrees geometry to one Mg2+ and one B3- atom. In the sixteenth H+0.80+ site, H+0.80+ is bonded in a single-bond geometry to one B3- atom. In the seventeenth H+0.80+ site, H+0.80+ is bonded in a single-bond geometry to one B3- atom. In the eighteenth H+0.80+ site, H+0.80+ is bonded in a distorted L-shaped geometry to one Mg2+ and one B3- atom. In the nineteenth H+0.80+ site, H+0.80+ is bonded in a single-bond geometry to one B3- atom. In the twentieth H+0.80+ site, H+0.80+ is bonded in a water-like geometry to one Mg2+ and one B3- atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on MgB4 by Materials Project

MgB4 is Magnesium tetraboride structured and crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. Mg is bonded in a 1-coordinate geometry to eleven B atoms. There are a spread of Mg–B bond distances ranging from 2.37–2.77 Å. There are three inequivalent B sites. In the first B site, B is bonded in a 6-coordinate geometry to two equivalent Mg and six B atoms. There are a spread of B–B bond distances ranging from 1.75–1.83 Å. In the second B site, B is bonded in a 7-coordinate geometry to three equivalent Mg and four B atoms. Both B–B bond lengths are 1.71 Å. In the third B site, B is bonded in a 8-coordinate geometry to three equivalent Mg and five B atoms. There is one shorter (1.69 Å) and one longer (1.80 Å) B–B bond length.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on MgB4(H9O8)2 by Materials Project

MgB4H16O15H2O crystallizes in the triclinic P-1 space group. The structure is zero-dimensional and consists of two water molecules and one MgB4H16O15 cluster. In the MgB4H16O15 cluster, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share a cornercorner with one BO4 tetrahedra. There are a spread of Mg–O bond distances ranging from 2.08–2.18 Å. There are four inequivalent B3+ sites. In the first B3+ site, B3+ is bonded to four O2- atoms to form BO4 tetrahedra that share a cornercorner with one MgO6 octahedra and a cornercorner with one BO4 tetrahedra. The corner-sharing octahedral tilt angles are 44°. There are a spread of B–O bond distances ranging from 1.46–1.52 Å. In the second B3+ site, B3+ is bonded in a trigonal planar geometry to three O2- atoms. All B–O bond lengths are 1.38 Å. In the third B3+ site, B3+ is bonded to four O2- atoms to form corner-sharing BO4 tetrahedra. There are a spread of B–O bond distances ranging from 1.46–1.51 Å. In the fourth B3+ site, B3+ is bonded in a trigonal planar geometry to three O2- atoms. All B–O bond lengths are 1.38 Å. There are sixteen inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. In the second H1+ site, H1+ is bonded in a distorted single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. In the third H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the fourth H1+ site, H1+ is bonded in a distorted single-bond geometry to two O2- atoms. There is one shorter (1.01 Å) and one longer (1.67 Å) H–O bond length. In the fifth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the sixth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. In the seventh H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the eighth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the ninth H1+ site, H1+ is bonded in a distorted single-bond geometry to one O2- atom. The H–O bond length is 1.01 Å. In the tenth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. In the eleventh H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the twelfth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. In the thirteenth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. In the fourteenth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the fifteenth H1+ site, H1+ is bonded in a distorted single-bond geometry to two O2- atoms. There is one shorter (1.01 Å) and one longer (1.63 Å) H–O bond length. In the sixteenth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. There are fifteen inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 120 degrees geometry to two B3+ atoms. In the second O2- site, O2- is bonded in a bent 120 degrees geometry to two B3+ atoms. In the third O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two B3+ atoms. In the fourth O2- site, O2- is bonded in a distorted trigonal planar geometry to two B3+ and one H1+ atom. In the fifth O2- site, O2- is bonded in a distorted trigonal planar geometry to two B3+ and one H1+ atom. In the sixth O2- site, O2- is bonded in a 3-coordinate geometry to one Mg2+, one B3+, and one H1+ atom. In the seventh O2- site, O2- is bonded in a bent 120 degrees geometry to one B3+ and one H1+ atom. In the eighth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one B3+ and one H1+ atom. In the ninth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one B3+ and one H1+ atom. In the tenth O2- site, O2- is bonded in a distorted water-like geometry to one Mg2+ and two H1+ atoms. In the eleventh O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to one Mg2+ and two H1+ atoms. In the twelfth O2- site, O2- is bonded in a distorted water-like geometry to one Mg2+ and two H1+ atoms. In the thirteenth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Mg2+ and two H1+ atoms. In the fourteenth O2- site, O2- is bonded in a distorted water-like geometry to one Mg2+ and two H1+ atoms. In the fifteenth O2- site, O2- is bonded in a water-like geometry to two H1+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Fabrication and characterization of nanoscale magnesium diboride and tetraboride for propulsion and hydrogen storage applications

Abstract: Boron-loaded propellants have the potential to dramatically increase the performance of solid fuel ramjets, ducted rockets, and hybrid rocket engines. However, difficult ignition of boron decreases the combustion efficiency of these propellants. One approach to solving this problem involves the use of magnesium diboride, MgB2, which ignites easier than boron. Magnesium tetraboride, MgB4, potentially offers greater energetic performance as B has a higher energy density than Mg. However, the effect of the higher boron/metal ratio on the ignition and combustion is unclear. Nanoscale MgB2 particles and quasi 2D structures are promising propellant ingredients, but the oxidation and combustion properties of nanoscale MgB4 remain unknown. Nanoscale magnesium borides are also of interest as precursors for the synthesis of magnesium borohydride, Mg(BH4)2, a promising hydrogen storage material, but hydrogenation of MgB4 has not been studied yet. The objectives of the present work included synthesis, purification, and high-energy ball milling of MgB2 and MgB4 powders as well as investigation of their hydrogen uptake, thermal decomposition, oxidation, and combustion. The powders were fabricated by combustion synthesis and by heating in a tube furnace. The latter method was superior in the synthesis of MgB4. Oxide impurities in the synthesized powders were removed by acid leaching. Nanoscale powders were obtained by ball-mill exfoliation. The hydrogen intake of the obtained magnesium borides was examined at 700 bar and 300 ℃ and did not reveal any advantage of MgB4 over MgB2. Their thermal decomposition and oxidation were investigated with thermogravimetric analysis (TGA), while their combustion was studied using laser ignition and high-speed video recording. TGA has confirmed prior observations of multistep decomposition of magnesium borides, where each step involves formation of a boride with a higher B/Mg ratio and evaporation of formed magnesium. The oxidation rates of the borides are much higher than that of boron at temperatures over 1200 °C for MgB2 and over 900 °C for MgB4. The burning rates of non-milled MgB₂ and MgB₄ powders were much higher than for the used submicron boron. Milling the MgB₂ and MgB₄ powders further increased their burning rates. The milled MgB4 burned 7.5 times faster than submicron boron.

Combustion of metals, Solid fuels, Propellants, Hy↗
DOE OSTI2025

Fabrication, oxidation, and combustion of nanoscale magnesium diboride and tetraboride

The difficult ignition of boron decreases the combustion efficiency of boron-loaded, fuel-rich propellants. One approach to solving this problem involves the use of magnesium diboride (MgB2), which ignites easier than boron. Magnesium tetraboride (MgB4) offers greater energy density owing to its higher boron content. However, the effect of B/Mg ratio on the ignition and combustion is unknown. Additionally, while nanoscale MgB₂ particles and quasi-2D structures were recently recognized as promising energetic additives, the oxidation and combustion properties of nanoscale MgB₄ have not been explored. The objectives of the present work included synthesis, purification, and high-energy ball milling of MgB2 and MgB4 powders as well as investigation of their thermal decomposition, oxidation, and combustion. The MgB2 and MgB4 powders were fabricated by combustion synthesis in the chemical oven mode and by heating Mg/B mixtures in a tube furnace. The latter method was superior in the synthesis of MgB4. Oxide impurities in the synthesized powders were removed by acid leaching. Nanoscale powders were obtained by high-energy ball milling. Thermal decomposition and oxidation of the obtained MgB₂ and MgB₄ powders were investigated by conducting non-isothermal thermogravimetric analysis (TGA) at temperatures up to 1550 °C in argon and oxygen flows. Combustion of B, MgB₂, and MgB₄ powders with oxygen at atmospheric pressure was studied in a windowed chamber using laser ignition and high-speed video recording. The TGA has shown multi-step decomposition of both magnesium borides in an argon environment. The maximum oxidation rate of MgB4 in oxygen was observed at a much lower temperature than in the case of MgB2. In the combustion experiments, both magnesium borides burned much faster than submicron boron. Ball milling of the borides further increased their burning rates. It has been concluded that nanoscale magnesium tetraboride is a promising ingredient for fuel-rich propellants owing to its high energy density, efficient oxidation, and rapid combustion.

Molina, Andre [The University of Texas at El Paso]↗
DOE OSTI2020

Materials Data on MgScB by Materials Project

MgScB is half-Heusler structured and crystallizes in the cubic F-43m space group. The structure is three-dimensional. Mg is bonded to four equivalent B atoms to form MgB4 tetrahedra that share corners with four equivalent ScB4 tetrahedra, corners with twelve equivalent MgB4 tetrahedra, and edges with six equivalent ScB4 tetrahedra. All Mg–B bond lengths are 2.52 Å. Sc is bonded to four equivalent B atoms to form ScB4 tetrahedra that share corners with four equivalent MgB4 tetrahedra, corners with twelve equivalent ScB4 tetrahedra, and edges with six equivalent MgB4 tetrahedra. All Sc–B bond lengths are 2.52 Å. B is bonded in a body-centered cubic geometry to four equivalent Mg and four equivalent Sc atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Combustion synthesis of nanoscale magnesium borides with improved hydrogen uptake and release

Four MgBx phases have been synthesized: MgB2, MgB4, MgB7, and MgB20. The phase composition depends on the heating time. Combustion synthesis cannot improve the product quality despite the very high heating rate; it also leads to loss of Mg. An effective acid leaching procedure has been identified for removal of MgO. Use of high-purity boron decreases the MgO impurity. First samples have been shipped to the Collaborator for investigating their hydrogenation at Sandia National Laboratories.

Molina, Andre↗