Search NASA⌕ Search

DOE OSTI · 1276512

Materials Data on Cs3As7 by Materials Project

Abstract

Cs3As7 crystallizes in the orthorhombic Pbca space group. The structure is three-dimensional. there are three inequivalent Cs1+ sites. In the first Cs1+ site, Cs1+ is bonded in a 8-coordinate geometry to eight As+0.43- atoms. There are a spread of Cs–As bond distances ranging from 3.69–3.89 Å. In the second Cs1+ site, Cs1+ is bonded in a 7-coordinate geometry to seven As+0.43- atoms. There are a spread of Cs–As bond distances ranging from 3.84–4.29 Å. In the third Cs1+ site, Cs1+ is bonded in a 7-coordinate geometry to eight As+0.43- atoms. There are a spread of Cs–As bond distances ranging from 3.76–4.19 Å. There are seven inequivalent As+0.43- sites. In the first As+0.43- site, As+0.43- is bonded in a 6-coordinate geometry to three Cs1+ and three As+0.43- atoms. There are a spread of As–As bond distances ranging from 2.40–2.58 Å. In the second As+0.43- site, As+0.43- is bonded to five Cs1+ and two As+0.43- atoms to form distorted AsCs5As2 pentagonal bipyramids that share corners with two equivalent AsCs3As3 octahedra, corners with four equivalent AsCs5As2 pentagonal bipyramids, corners with five equivalent AsCs4As2 pentagonal pyramids, a cornercorner with one AsCs3As2 square pyramid, an edgeedge with one AsCs3As3 octahedra, an edgeedge with one AsCs4As2 pentagonal pyramid, and edges with two equivalent AsCs3As2 square pyramids. The corner-sharing octahedra tilt angles range from 71–143°. The As–As bond length is 2.46 Å. In the third As+0.43- site, As+0.43- is bonded to three Cs1+ and two As+0.43- atoms to form distorted AsCs3As2 square pyramids that share corners with three equivalent AsCs3As3 octahedra, a cornercorner with one AsCs5As2 pentagonal bipyramid, corners with four equivalent AsCs4As2 pentagonal pyramids, an edgeedge with one AsCs3As3 octahedra, edges with two equivalent AsCs5As2 pentagonal bipyramids, an edgeedge with one AsCs4As2 pentagonal pyramid, and an edgeedge with one AsCs3As2 square pyramid. The corner-sharing octahedra tilt angles range from 28–60°. There are one shorter (2.39 Å) and one longer (2.44 Å) As–As bond lengths. In the fourth As+0.43- site, As+0.43- is bonded to three Cs1+ and three As+0.43- atoms to form distorted AsCs3As3 octahedra that share corners with two equivalent AsCs5As2 pentagonal bipyramids, corners with three equivalent AsCs4As2 pentagonal pyramids, corners with three equivalent AsCs3As2 square pyramids, an edgeedge with one AsCs3As3 octahedra, an edgeedge with one AsCs5As2 pentagonal bipyramid, an edgeedge with one AsCs4As2 pentagonal pyramid, and an edgeedge with one AsCs3As2 square pyramid. The As–As bond length is 2.45 Å. In the fifth As+0.43- site, As+0.43- is bonded to four Cs1+ and two As+0.43- atoms to form distorted AsCs4As2 pentagonal pyramids that share corners with three equivalent AsCs3As3 octahedra, corners with five equivalent AsCs5As2 pentagonal bipyramids, corners with two equivalent AsCs4As2 pentagonal pyramids, corners with four equivalent AsCs3As2 square pyramids, an edgeedge with one AsCs3As3 octahedra, an edgeedge with one AsCs5As2 pentagonal bipyramid, and an edgeedge with one AsCs3As2 square pyramid. The corner-sharing octahedra tilt angles range from 55–143°. The As–As bond length is 2.38 Å. In the sixth As+0.43- site, As+0.43- is bonded in a 6-coordinate geometry to three Cs1+ and three As+0.43- atoms. The As–As bond length is 2.54 Å. In the seventh As+0.43- site, As+0.43- is bonded in a 5-coordinate geometry to two equivalent Cs1+ and three As+0.43- atoms.

Explore related subjects

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

2020-04-29. Materials Data on Cs3As7 by Materials Project. https://doi.org/10.17188/1276512

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↗