Search NASA⌕ Search
Home/Archive/DOE OSTI

DOE OSTI · 1313330

Materials Data on HfFe2 by Materials Project

View original source ↗Read source document ↗Export metadata ↓

Abstract

HfFe2 is Hexagonal Laves structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Hf is bonded in a 12-coordinate geometry to twelve Fe atoms. There are three shorter (2.88 Å) and nine longer (2.90 Å) Hf–Fe bond lengths. There are two inequivalent Fe sites. In the first Fe site, Fe is bonded to six equivalent Hf and six equivalent Fe atoms to form a mixture of corner, edge, and face-sharing FeHf6Fe6 cuboctahedra. All Fe–Fe bond lengths are 2.47 Å. In the second Fe site, Fe is bonded to six equivalent Hf and six Fe atoms to form a mixture of corner, edge, and face-sharing FeHf6Fe6 cuboctahedra. There are two shorter (2.45 Å) and two longer (2.50 Å) Fe–Fe bond lengths.

Explore related subjects

36 MATERIALS SCIENCEcrystal structureFe-HfHfFe2

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

2020-07-14. Materials Data on HfFe2 by Materials Project. https://doi.org/10.17188/1313330

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

KEEP EXPLORING

Related reports

DOE OSTI2026

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↗