Search NASA⌕ Search

DOE OSTI · 1757508

Materials Data on Fe5(OF4)2 by Materials Project

Abstract

Fe5(OF4)2 is zeta iron carbide-derived structured and crystallizes in the monoclinic C2 space group. The structure is three-dimensional. there are six inequivalent Fe+2.40+ sites. In the first Fe+2.40+ site, Fe+2.40+ is bonded to one O2- and five F1- atoms to form FeOF5 octahedra that share corners with eight FeO2F4 octahedra and edges with two FeOF5 octahedra. The corner-sharing octahedra tilt angles range from 47–56°. The Fe–O bond length is 2.03 Å. There are a spread of Fe–F bond distances ranging from 2.11–2.21 Å. In the second Fe+2.40+ site, Fe+2.40+ is bonded to one O2- and five F1- atoms to form a mixture of corner and edge-sharing FeOF5 octahedra. The corner-sharing octahedra tilt angles range from 35–67°. The Fe–O bond length is 1.98 Å. There are a spread of Fe–F bond distances ranging from 2.10–2.23 Å. In the third Fe+2.40+ site, Fe+2.40+ is bonded to two equivalent O2- and four F1- atoms to form a mixture of corner and edge-sharing FeO2F4 octahedra. The corner-sharing octahedra tilt angles range from 41–55°. Both Fe–O bond lengths are 1.89 Å. There are two shorter (2.02 Å) and two longer (2.27 Å) Fe–F bond lengths. In the fourth Fe+2.40+ site, Fe+2.40+ is bonded to two equivalent O2- and four F1- atoms to form a mixture of corner and edge-sharing FeO2F4 octahedra. The corner-sharing octahedra tilt angles range from 47–50°. Both Fe–O bond lengths are 1.94 Å. There are two shorter (2.01 Å) and two longer (2.11 Å) Fe–F bond lengths. In the fifth Fe+2.40+ site, Fe+2.40+ is bonded to one O2- and five F1- atoms to form a mixture of corner and edge-sharing FeOF5 octahedra. The corner-sharing octahedra tilt angles range from 41–67°. The Fe–O bond length is 1.98 Å. There are a spread of Fe–F bond distances ranging from 2.07–2.28 Å. In the sixth Fe+2.40+ site, Fe+2.40+ is bonded to one O2- and five F1- atoms to form FeOF5 octahedra that share corners with eight FeOF5 octahedra and edges with two FeO2F4 octahedra. The corner-sharing octahedra tilt angles range from 35–56°. The Fe–O bond length is 1.91 Å. There are a spread of Fe–F bond distances ranging from 1.96–2.12 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a trigonal planar geometry to three Fe+2.40+ atoms. In the second O2- site, O2- is bonded in a trigonal planar geometry to three Fe+2.40+ atoms. There are nine inequivalent F1- sites. In the first F1- site, F1- is bonded in a distorted trigonal planar geometry to three Fe+2.40+ atoms. In the second F1- site, F1- is bonded in a distorted trigonal planar geometry to three Fe+2.40+ atoms. In the third F1- site, F1- is bonded in a 3-coordinate geometry to three Fe+2.40+ atoms. In the fourth F1- site, F1- is bonded in a distorted trigonal planar geometry to three Fe+2.40+ atoms. In the fifth F1- site, F1- is bonded in a 3-coordinate geometry to three Fe+2.40+ atoms. In the sixth F1- site, F1- is bonded in a distorted trigonal planar geometry to three Fe+2.40+ atoms. In the seventh F1- site, F1- is bonded in a distorted trigonal planar geometry to three Fe+2.40+ atoms. In the eighth F1- site, F1- is bonded in a distorted trigonal planar geometry to three Fe+2.40+ atoms. In the ninth F1- site, F1- is bonded in a 3-coordinate geometry to three Fe+2.40+ atoms.

Explore related subjects

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

2020-09-03. Materials Data on Fe5(OF4)2 by Materials Project. https://doi.org/10.17188/1757508

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related reports

Cyclic moisture reactivation of calcium sorbents for long duration thermochemical energy storage

The transition to a flexible and reliable energy infrastructure, using electro-thermal energy generation technologies such as geothermal, concentrated solar power, and nuclear, usually demands simultaneous advancement of thermal energy storage (TES) to support on-demand electricity generation and industrial applications while mitigating the inherent intermittency of renewable energy sources and power outages from direct energy generation. Among TES technologies, thermochemical energy storage (TCES) based on calcium looping emerges as a compelling high-power energy storage candidate due to its high reaction enthalpy, compatibility with elevated operating temperatures, and abundance of low-cost materials. However, the long-term durability of calcium-based sorbents for TCES is hindered by surface sintering and particle aggregation, leading to performance degradation over repeated thermal cycles. This study explores a moisture hydration-based strategy to regenerate a degraded calcium sorbent and mitigate performance degradation for long duration TCES. The addition of moisture transforms calcium oxide into calcium hydroxide and produces intercalation water layers, associated with a regenerated surface area and reduced calcium oxide crystallite size. Both these effects are beneficial in restoring the sorbents' reactivity for carbonization. Additionally, an optimized hydration-assisted reactivation protocol balances the recovered energy storage capacity with heating penalty required for moisture removal from hydrated samples, resulting in an enhanced energy storage capacity up to 176% compared to benchmark sorbents that undergo cycling without reactivation after 60 cycles. In conclusion, these results highlight the potential of hydration-assisted reactivation to enhance the long-term performance of TCES, providing an effective pathway to advancing electro-thermal storage technologies.

36 MATERIALS SCIENCE↗