Search NASA⌕ Search

DOE OSTI · 1296829

Materials Data on Ba2Ca7I18 by Materials Project

Abstract

Ba2Ca7I18 crystallizes in the triclinic P-1 space group. The structure is three-dimensional. Ba2+ is bonded in a 7-coordinate geometry to seven I1- atoms. There are a spread of Ba–I bond distances ranging from 3.52–4.23 Å. There are four inequivalent Ca2+ sites. In the first Ca2+ site, Ca2+ is bonded to six I1- atoms to form a mixture of edge and corner-sharing CaI6 octahedra. The corner-sharing octahedra tilt angles range from 50–62°. There are a spread of Ca–I bond distances ranging from 3.08–3.28 Å. In the second Ca2+ site, Ca2+ is bonded to six I1- atoms to form a mixture of edge and corner-sharing CaI6 octahedra. The corner-sharing octahedra tilt angles range from 57–60°. There are a spread of Ca–I bond distances ranging from 3.12–3.20 Å. In the third Ca2+ site, Ca2+ is bonded to six I1- atoms to form a mixture of edge and corner-sharing CaI6 octahedra. The corner-sharing octahedra tilt angles range from 53–58°. There are a spread of Ca–I bond distances ranging from 3.11–3.23 Å. In the fourth Ca2+ site, Ca2+ is bonded to six I1- atoms to form a mixture of edge and corner-sharing CaI6 octahedra. The corner-sharing octahedra tilt angles range from 50–62°. There are a spread of Ca–I bond distances ranging from 3.07–3.25 Å. There are nine inequivalent I1- sites. In the first I1- site, I1- is bonded in a distorted bent 120 degrees geometry to one Ba2+ and two Ca2+ atoms. In the second I1- site, I1- is bonded in a distorted trigonal non-coplanar geometry to one Ba2+ and two Ca2+ atoms. In the third I1- site, I1- is bonded in a distorted trigonal non-coplanar geometry to one Ba2+ and two Ca2+ atoms. In the fourth I1- site, I1- is bonded in a distorted trigonal planar geometry to three Ca2+ atoms. In the fifth I1- site, I1- is bonded in a 3-coordinate geometry to three Ca2+ atoms. In the sixth I1- site, I1- is bonded in a 3-coordinate geometry to one Ba2+ and two Ca2+ atoms. In the seventh I1- site, I1- is bonded in an L-shaped geometry to two Ca2+ atoms. In the eighth I1- site, I1- is bonded in a 3-coordinate geometry to one Ba2+ and three Ca2+ atoms. In the ninth I1- site, I1- is bonded to two equivalent Ba2+ and two Ca2+ atoms to form a mixture of distorted edge and corner-sharing IBa2Ca2 trigonal pyramids.

Explore related subjects

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

2020-07-15. Materials Data on Ba2Ca7I18 by Materials Project. https://doi.org/10.17188/1296829

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↗