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All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on FeSiO4 by Materials Project

FeSiO4 crystallizes in the orthorhombic Pnma space group. The structure is two-dimensional and consists of two FeSiO4 sheets oriented in the (0, 0, 1) direction. Fe is bonded to four O atoms to form FeO4 tetrahedra that share corners with four equivalent SiO4 tetrahedra. There is three shorter (1.85 Å) and one longer (1.86 Å) Fe–O bond length. Si is bonded to four O atoms to form SiO4 tetrahedra that share corners with four equivalent FeO4 tetrahedra. There are a spread of Si–O bond distances ranging from 1.63–1.65 Å. There are three inequivalent O sites. In the first O site, O is bonded in a bent 150 degrees geometry to one Fe and one Si atom. In the second O site, O is bonded in a bent 150 degrees geometry to one Fe and one Si atom. In the third O site, O is bonded in a bent 120 degrees geometry to one Fe and one Si atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on FeSiO4 by Materials Project

FeSiO4 crystallizes in the monoclinic P2_1/c space group. The structure is two-dimensional and consists of one FeSiO4 sheet oriented in the (-1, 0, 2) direction. Fe is bonded to four O atoms to form FeO4 tetrahedra that share corners with four equivalent SiO4 tetrahedra. There is two shorter (1.84 Å) and two longer (1.85 Å) Fe–O bond length. Si is bonded to four O atoms to form SiO4 tetrahedra that share corners with four equivalent FeO4 tetrahedra. There are a spread of Si–O bond distances ranging from 1.63–1.65 Å. There are four inequivalent O sites. In the first O site, O is bonded in a bent 120 degrees geometry to one Fe and one Si atom. In the second O site, O is bonded in a bent 120 degrees geometry to one Fe and one Si atom. In the third O site, O is bonded in a bent 150 degrees geometry to one Fe and one Si atom. In the fourth O site, O is bonded in a bent 150 degrees geometry to one Fe and one Si atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on FeSiO4 by Materials Project

Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

36 MATERIALS SCIENCE↗
NASA NTRS2012

Collisional Histories of Comets and Trojan Asteroids: Diopside, Magnesite, and Fayalite Impact Studies

Comets and asteroids have weathered dynamic histories, as evidenced by their rough surfaces. The Nice model describes a violent reshuffling of small bodies during the Late Heavy Bombardment, with collisions acting to grind these planetesimals away. This creates an additional source of impact material that can re-work the surfaces of the larger bodies over the lifetime of the solar system. Here, we investigate the possibility that signatures due to impacts (e.g. from micrometeoroids or meteoroids) could be detected in their spectra, and how that can be explained by the physical manifestation of shock in the crystalline structure of minerals. All impact experiments were conducted in the Johnson Space Center Experimental Impact Laboratory using the vertical gun. Impact speeds ranged from approx.2.0 km/s to approx.2.8 km/s. All experiments were conducted at room temperature. Minerals found in comets and asteroids were chosen as targets, including diopside (MgCaSi2O6, monoclinic pyroxene), magnesite (MgCO3, carbonate), and fayalite (FeSiO4, olivine). Impacted samples were analyzed using a Fourier Transform Infrared Spectrometer (FTIR) and a Transmission Electron Microscope (TEM). Absorbance features in the 8-13 m spectral region demonstrate relative amplitude changes as well as wavelength shifts. Corresponding TEM images exhibit planar shock dislocations in the crystalline structure, attributed to deformation at high strain and low temperatures. Elongating or shortening the axes of the crystalline structure of forsterite (Mg2SiO4, olivine) using a discrete dipole approximation model (Lindsay et al., submitted) yields changes in spectral features similar to those observed in our impacted laboratory minerals.

Lederer, S. M.↗