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All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on Mg(PO3)2 by Materials Project

Mg(PO3)2 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. there are two inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with six PO4 tetrahedra and edges with two equivalent MgO6 octahedra. There are a spread of Mg–O bond distances ranging from 2.01–2.19 Å. In the second Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with six PO4 tetrahedra and edges with two equivalent MgO6 octahedra. There are two shorter (2.05 Å) and four longer (2.12 Å) Mg–O bond lengths. There are two inequivalent P5+ sites. In the first P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with three MgO6 octahedra and corners with two equivalent PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 19–58°. 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 three MgO6 octahedra and corners with two equivalent PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 21–58°. There are a spread of P–O bond distances ranging from 1.48–1.61 Å. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two P5+ atoms. In the second O2- site, O2- is bonded in a bent 150 degrees geometry to one Mg2+ and one P5+ atom. In the third O2- site, O2- is bonded in a distorted trigonal planar geometry to two Mg2+ and one P5+ atom. In the fourth O2- site, O2- is bonded in a bent 150 degrees geometry to two P5+ atoms. In the fifth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Mg2+ and one P5+ atom. In the sixth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Mg2+ and one P5+ atom.

36 MATERIALS SCIENCE↗
NASA NTRS2018

Experimental Study into the Stability of Whitlockite and Hydroxylapatite in Basaltic Magmas

Apatite (Ca5(PO4)3(F,Cl,OH)), merrillite (Ca18Na2Mg2(PO4)14), and whitlockite (Ca9(Mg,Fe(2+))(PO4)6[PO3(OH)]) are the primary phosphate minerals found in most planetary materials including rocks from Earth, Moon, Mars, and asteroids. For many years, the terms merrillite and whitlockite have been used interchangeably in the meteorite literature. Much of the confusion regarding the relationship between terrestrial and extraterrestrial 'whitlockite' is based on the presence or absence of hydrogen in the mineral structure. Whitlockite has approximately 8500 ppm H2O, and the term 'merrillite' has been adopted to identify the hydrogen-free form of whitlockite. The atomic structures of merrillite and whitlockite were examined in detail by Hughes et al.. On Earth, whitlockite has been found in rocks from evolved pegmatitic systems and in some mantle rocks. Furthermore, terrestrial whitlockite has been shown to have some merrillite component. For the meteoritic and lunar materials that have been investigated, merrillite appears to be far more common than whitlockite, and it has been proposed that the whitlockite component is unique to terrestrial samples. There are some reports of 'whitlockite' in the meteorite literature; however, these may represent misidentifications of merrillite because there have been no reports of extraterrestrial whitlockite that have been verified through crystal structural studies or analyzed for their H contents. Hughes et al. reported the atomic arrangement of lunar merrillite and demonstrated that the phase is similar to meteoritic merrillite and, predictably, devoid of hydrogen. In a follow-up study, Hughes et al. reported the atomic arrangements of two natural samples of whitlockite, one synthetic whitlockite, and samples of synthetic whitlockite that were heated at 500 C or 1050 C for 24 h. The crystal chemistry and crystal structures of the phases were compared, and it was discovered that the latter treatment resulted in the dehydrogenation of whitlockite to form merrillite.

McCubbin, F. M.↗
DOE OSTI2020

Materials Data on MgAg(PO3)3 by Materials Project

MgAg(PO3)3 crystallizes in the orthorhombic Pcca space group. The structure is three-dimensional. there are two inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with six PO4 tetrahedra. There are a spread of Mg–O bond distances ranging from 2.04–2.15 Å. In the second Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with six PO4 tetrahedra. There are a spread of Mg–O bond distances ranging from 2.07–2.12 Å. Ag1+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Ag–O bond distances ranging from 2.39–2.83 Å. There are three inequivalent P5+ sites. In the first P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two MgO6 octahedra and corners with two PO4 tetrahedra. The corner-sharing octahedral tilt angles are 44°. There is two shorter (1.50 Å) and two longer (1.62 Å) P–O bond length. In the second P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two equivalent MgO6 octahedra and corners with two PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 38–53°. There are a spread of P–O bond distances ranging from 1.50–1.62 Å. In the third P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two equivalent MgO6 octahedra and corners with two PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 37–53°. There are a spread of P–O bond distances ranging from 1.49–1.63 Å. There are ten inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to one Mg2+, one Ag1+, and one P5+ atom. In the second O2- site, O2- is bonded in a 2-coordinate geometry to one Mg2+, one Ag1+, and one P5+ atom. In the third O2- site, O2- is bonded in a bent 120 degrees geometry to two equivalent P5+ atoms. In the fourth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Mg2+, one Ag1+, and one P5+ atom. In the fifth O2- site, O2- is bonded in a 2-coordinate geometry to one Mg2+, one Ag1+, and one P5+ atom. In the sixth O2- site, O2- is bonded in a bent 120 degrees geometry to two P5+ atoms. In the seventh O2- site, O2- is bonded in a 3-coordinate geometry to one Mg2+, one Ag1+, and one P5+ atom. In the eighth O2- site, O2- is bonded in a bent 150 degrees geometry to two equivalent P5+ atoms. In the ninth O2- site, O2- is bonded in a bent 120 degrees geometry to two P5+ atoms. In the tenth O2- site, O2- is bonded in a 2-coordinate geometry to one Mg2+, one Ag1+, and one P5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on KMg(PO3)3 by Materials Project

KMg(PO3)3 crystallizes in the hexagonal P-6c2 space group. The structure is three-dimensional. K1+ is bonded in a 6-coordinate geometry to six equivalent O2- atoms. All K–O bond lengths are 2.83 Å. Mg2+ is bonded to six equivalent O2- atoms to form MgO6 octahedra that share corners with six equivalent PO4 tetrahedra. All Mg–O bond lengths are 2.10 Å. P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two equivalent MgO6 octahedra and corners with two equivalent PO4 tetrahedra. The corner-sharing octahedral tilt angles are 41°. There are a spread of P–O bond distances ranging from 1.50–1.62 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to one K1+, one Mg2+, and one P5+ atom. In the second O2- site, O2- is bonded in a bent 150 degrees geometry to two equivalent P5+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Cs3Mg3In(PO3)12 by Materials Project

Cs3Mg3In(PO3)12 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are three inequivalent Cs1+ sites. In the first Cs1+ site, Cs1+ is bonded in a 12-coordinate geometry to twelve O2- atoms. There are a spread of Cs–O bond distances ranging from 3.05–3.64 Å. In the second Cs1+ site, Cs1+ is bonded in a 10-coordinate geometry to ten O2- atoms. There are a spread of Cs–O bond distances ranging from 3.11–3.67 Å. In the third Cs1+ site, Cs1+ is bonded in a 12-coordinate geometry to twelve O2- atoms. There are a spread of Cs–O bond distances ranging from 3.05–3.65 Å. There are three inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with six PO4 tetrahedra. There are a spread of Mg–O bond distances ranging from 2.09–2.20 Å. In the second Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with six PO4 tetrahedra. There are a spread of Mg–O bond distances ranging from 2.07–2.13 Å. In the third Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with six PO4 tetrahedra. There are a spread of Mg–O bond distances ranging from 2.11–2.20 Å. In3+ is bonded to six O2- atoms to form InO6 octahedra that share corners with six PO4 tetrahedra. There are a spread of In–O bond distances ranging from 2.13–2.19 Å. There are twelve inequivalent P5+ sites. In the first P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share a cornercorner with one MgO6 octahedra, a cornercorner with one InO6 octahedra, and corners with two PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 47–56°. There are a spread of P–O bond distances ranging from 1.49–1.59 Å. In the second P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two MgO6 octahedra and corners with two PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 44–45°. There are a spread of P–O bond distances ranging from 1.50–1.64 Å. In the third P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share a cornercorner with one MgO6 octahedra, a cornercorner with one InO6 octahedra, and corners with two PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 41–46°. There are a spread of P–O bond distances ranging from 1.49–1.63 Å. In the fourth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two MgO6 octahedra and corners with two PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 43–45°. There are a spread of P–O bond distances ranging from 1.49–1.64 Å. In the fifth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share a cornercorner with one MgO6 octahedra, a cornercorner with one InO6 octahedra, and corners with two PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 43–46°. There are a spread of P–O bond distances ranging from 1.49–1.63 Å. In the sixth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two MgO6 octahedra and corners with two PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 35–53°. There is two shorter (1.50 Å) and two longer (1.63 Å) P–O bond length. In the seventh P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share a cornercorner with one MgO6 octahedra, a cornercorner with one InO6 octahedra, and corners with two PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 37–57°. There are a spread of P–O bond distances ranging from 1.49–1.61 Å. In the eighth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share a cornercorner with one MgO6 octahedra, a cornercorner with one InO6 octahedra, and corners with two PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 43–44°. There are a spread of P–O bond distances ranging from 1.49–1.64 Å. In the ninth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two MgO6 octahedra and corners with two PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 44–45°. There are a spread of P–O bond distances ranging from 1.50–1.65 Å. In the tenth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share a cornercorner with one MgO6 octahedra, a cornercorner with one InO6 octahedra, and corners with two PO4 tetrahedra. The corner-sharing octahedral tilt angles are 43°. There are a spread of P–O bond distances ranging from 1.49–1.64 Å. In the eleventh P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two MgO6 octahedra and corners with two PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 44–45°. There are a spread of P–O bond distances ranging from 1.50–1.64 Å. In the twelfth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two MgO6 octahedra and corners with two PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 44–54°. There is two shorter (1.50 Å) and two longer (1.60 Å) P–O bond length. There are thirty-six inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two Cs1+, one Mg2+, and one P5+ atom. In the second O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two Cs1+, one Mg2+, and one P5+ atom. In the third O2- site, O2- is bonded in a bent 120 degrees geometry to two P5+ atoms. In the fourth O2- site, O2- is bonded in a 2-coordinate geometry to one Cs1+, one Mg2+, and one P5+ atom. In the fifth O2- site, O2- is bonded in a bent 120 degrees geometry to two P5+ atoms. In the sixth O2- site, O2- is bonded in a bent 120 degrees geometry to two P5+ atoms. In the seventh O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Mg2+ and one P5+ atom. In the eighth O2- site, O2- is bonded in a 2-coordinate geometry to one Cs1+, one Mg2+, and one P5+ atom. In the ninth O2- site, O2- is bonded in a 2-coordinate geometry to one Cs1+, one Mg2+, and one P5+ atom. In the tenth O2- site, O2- is bonded in a 2-coordinate geometry to one Cs1+, one Mg2+, and one P5+ atom. In the eleventh O2- site, O2- is bonded in a bent 120 degrees geometry to two P5+ atoms. In the twelfth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Cs1+ and two P5+ atoms. In the thirteenth O2- site, O2- is bonded in a 2-coordinate geometry to two Cs1+, one Mg2+, and one P5+ atom. In the fourteenth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Mg2+ and one P5+ atom. In the fifteenth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Cs1+ and two P5+ atoms. In the sixteenth O2- site, O2- is bonded in a 2-coordinate geometry to two Cs1+, one In3+, and one P5+ atom. In the seventeenth O2- site, O2- is bonded in a 2-coordinate geometry to one Cs1+, one Mg2+, and one P5+ atom. In the eighteenth O2- site, O2- is bonded in a bent 150 degrees geometry to two Cs1+, one Mg2+, and one P5+ atom. In the nineteenth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two Cs1+, one Mg2+, and one P5+ atom. In the twentieth O2- site, O2- is bonded in a 2-coordinate geometry to one Cs1+, one In3+, and one P5+ atom. In the twenty-first O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two Cs1+, one Mg2+, and one P5+ atom. In the twenty-second O2- site, O2- is bonded in a 2-coordinate geometry to one Cs1+ and two P5+ atoms. In the twenty-third O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one In3+ and one P5+ atom. In the twenty-fourth O2- site, O2- is bonded in a 2-coordinate geometry to two Cs1+, one In3+, and one P5+ atom. In the twenty-fifth O2- site, O2- is bonded in a 2-coordinate geometry to one Cs1+ and two P5+ atoms. In the twenty-sixth O2- site, O2- is bonded in a bent 120 degrees geometry to two P5+ atoms. In the twenty-seventh O2- site, O2- is bonded in a 2-coordinate geometry to one Cs1+, one Mg2+, and one P5+ atom. In the twenty-eighth O2- site, O2- is bonded in a 2-coordinate geometry to one Cs1+, one Mg2+, and one P5+ atom. In the twenty-ninth O2- site, O2- is bonded in a 2-coordinate geometry to one Cs1+, one Mg2+, and one P5+ atom. In the thirtieth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one In3+ and one P5+ atom. In the thirty-first O2- site, O2- is bonded in a bent 120 degrees geometry to two P5+ atoms. In the thirty-second O2- site, O2- is bonded in a bent 120 degrees geometry to two P5+ atoms. In the thirty-third O2- site, O2- is bonded in a 2-coordinate geometry to one Cs1+, one Mg2+, and one P5+ atom. In the thirty-fourth O2- site, O2- is bonded in a bent 120 degrees geometry to two P5+ atoms. In the thirty-fifth O2- site, O2- is bonded in a 2-coordinate geometry to two Cs1+, one In3+, and one P5+ atom. In the thirty-sixth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two Cs1+, one Mg2+, and one P5+ atom.

36 MATERIALS SCIENCE↗
NASA NTRS2017

Experimental Study into the Stability of Whitlockite in Basaltic Magmas

Apatite Ca5(PO4)3(F,Cl,OH), merrillite Ca18Na2Mg2(PO4)14, and whitlockite Ca9(Mg,Fe2+)(PO4)6[PO3(OH)] are the primary phosphate minerals found in most planetary materials including rocks from Earth, Moon, Mars, and asteroids [1-2]. For many years, the terms merrillite and whitlockite have been used interchangeably in the meteorite literature. Much of the confusion regarding the relationship between terrestrial and extraterrestrial "whitlockite" is based on the presence or absence of hydrogen in the mineral structure. Whitlockite has approximately 8500 ppm H2O, and the term "merrillite" has been adopted to identify the hydrogen-free form of whitlockite [2]. The atomic structures of merrillite and whitlockite were examined in detail by Hughes et al. [3-4]. On Earth, whitlockite has been found in rocks from evolved pegmatitic systems [2-4] and in some mantle rocks [e.g., 5]. Furthermore, terrestrial whitlockite has been shown to have some merrillite component [4]. For the meteoritic and lunar materials that have been investigated, merrillite appears to be far more common than whitlockite, and it has been proposed that the whitlockite component is unique to terrestrial samples [4]. There are some reports of "whitlockite" in the meteorite literature; however, these likely represent misidentifications of merrillite because there have been no reports of extraterrestrial whitlockite that have been verified through crystal structural studies or analyzed for their H contents. Hughes et al. [3] reported the atomic arrangement of lunar merrillite and demonstrated that the phase is similar to meteoritic merrillite and, predictably, devoid of hydrogen. In a follow-up study, Hughes et al. [4] reported the atomic arrangements of two natural samples of whitlockite, one synthetic whitlockite, and samples of synthetic whitlockite that were heated at 500degC and 1050degC for 24 h. The crystal chemistry and crystal structures of the phases were compared, and it was discovered that the latter treatment resulted in the dehydrogenation of whitlockite to form merrillite. The presence of merrillite vs. whitlockite was widely thought to serve as an indication that magmas were anhydrous [e.g., 6-7]. However, McCubbin et al., [8] determined that merrillite in the martian meteorite Shergotty had no discernible whitlockite component despite its coexistence with OH-rich apatite. Consequently, McCubbin et al., (2014) speculated that the absence of a whitlockite component in Shergotty merrillite and other planetary merrillites may be a consequence of the limited thermal stability of H in whitlockite (stable only at T less than1050degC), which would prohibit merrillite-whitlockite solid-solution at high temperatures. In the present study, we have aimed to test this hypothesis experimentally by examining the stability of whitlockite in basaltic magmas at 1.2 GPa and a temperature range of -1000- 1300degC.

McCubbin, F. M.↗