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All sourcesNASA NTRSDOE OSTI
NASA NTRS1974

Minor and trace element distribution in melilite and pyroxene from the Allende meteorite

Melilite and pyroxene were separated from a coarsely crystalline chondrule in the Allende meteorite and analyzed by microprobe and spark source mass spectrometer techniques. Elemental abundances in the bulk chondrule are consistent with a mixture of equal amounts of the two minerals, as observed microscopically. The lanthanide distributions are markedly different in the two minerals; relative to chondrite abundances, melilite shows progressive depletion of the lanthanides La-Sm, a positive Eu anomaly, and relatively constant abundances of the heavier lanthanides (Gd-Yb, and Y) whereas pyroxene shows progressive enrichment towards the heavier lanthanides, on which is superimposed a negative Eu anomaly. Both minerals, and the bulk chondrule, show unusual concentrations of the platinum metals, but the crystallographic site or sites of these metals remains to be determined.

Mason, B.↗
DOE OSTI2020

Materials Data on LaSm3 by Materials Project

Sm3La is beta Cu3Ti-like structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. there are two inequivalent Sm sites. In the first Sm site, Sm is bonded to eight equivalent Sm and four equivalent La atoms to form SmLa4Sm8 cuboctahedra that share corners with four equivalent LaSm12 cuboctahedra, corners with fourteen equivalent SmLa4Sm8 cuboctahedra, edges with six equivalent LaSm12 cuboctahedra, edges with twelve equivalent SmLa4Sm8 cuboctahedra, faces with four equivalent LaSm12 cuboctahedra, and faces with sixteen SmLa4Sm8 cuboctahedra. There are a spread of Sm–Sm bond distances ranging from 3.64–3.70 Å. There are two shorter (3.67 Å) and two longer (3.68 Å) Sm–La bond lengths. In the second Sm site, Sm is bonded to eight equivalent Sm and four equivalent La atoms to form SmLa4Sm8 cuboctahedra that share corners with four equivalent LaSm12 cuboctahedra, corners with fourteen SmLa4Sm8 cuboctahedra, edges with six equivalent LaSm12 cuboctahedra, edges with twelve equivalent SmLa4Sm8 cuboctahedra, faces with four equivalent LaSm12 cuboctahedra, and faces with sixteen SmLa4Sm8 cuboctahedra. There are a spread of Sm–Sm bond distances ranging from 3.64–3.70 Å. There are two shorter (3.67 Å) and two longer (3.68 Å) Sm–La bond lengths. La is bonded to twelve Sm atoms to form LaSm12 cuboctahedra that share corners with six equivalent LaSm12 cuboctahedra, corners with twelve equivalent SmLa4Sm8 cuboctahedra, edges with eighteen SmLa4Sm8 cuboctahedra, faces with eight equivalent LaSm12 cuboctahedra, and faces with twelve SmLa4Sm8 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on La3Sm by Materials Project

SmLa3 is alpha La-derived structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Sm is bonded to twelve La atoms to form SmLa12 cuboctahedra that share corners with four equivalent SmLa12 cuboctahedra, corners with eight equivalent LaLa8Sm4 cuboctahedra, edges with eight equivalent SmLa12 cuboctahedra, edges with sixteen equivalent LaLa8Sm4 cuboctahedra, faces with four equivalent SmLa12 cuboctahedra, and faces with fourteen LaLa8Sm4 cuboctahedra. There are four shorter (3.71 Å) and eight longer (3.73 Å) Sm–La bond lengths. There are two inequivalent La sites. In the first La site, La is bonded to four equivalent Sm and eight La atoms to form LaLa8Sm4 cuboctahedra that share corners with twelve equivalent LaLa8Sm4 cuboctahedra, edges with eight equivalent SmLa12 cuboctahedra, edges with sixteen LaLa8Sm4 cuboctahedra, faces with four equivalent SmLa12 cuboctahedra, and faces with fourteen LaLa8Sm4 cuboctahedra. There are four shorter (3.71 Å) and four longer (3.73 Å) La–La bond lengths. In the second La site, La is bonded to four equivalent Sm and eight equivalent La atoms to form LaLa8Sm4 cuboctahedra that share corners with four equivalent LaLa8Sm4 cuboctahedra, corners with eight equivalent SmLa12 cuboctahedra, edges with twenty-four LaLa8Sm4 cuboctahedra, faces with six equivalent SmLa12 cuboctahedra, and faces with twelve LaLa8Sm4 cuboctahedra.

36 MATERIALS SCIENCE↗