Search NASA⌕ Search

DOE OSTI · 1275828

Materials Data on Ba14Na21CaN6 by Materials Project

Abstract

Na21Ba14CaN6 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. there are nine inequivalent Na sites. In the first Na site, Na is bonded in a 2-coordinate geometry to six Na and two equivalent Ba atoms. There are a spread of Na–Na bond distances ranging from 3.61–3.97 Å. Both Na–Ba bond lengths are 4.27 Å. In the second Na site, Na is bonded in a 9-coordinate geometry to six Na and three Ba atoms. There are a spread of Na–Na bond distances ranging from 3.55–3.81 Å. There are a spread of Na–Ba bond distances ranging from 4.25–4.46 Å. In the third Na site, Na is bonded in a 9-coordinate geometry to five Na and four Ba atoms. The Na–Na bond length is 3.92 Å. There are a spread of Na–Ba bond distances ranging from 4.04–4.17 Å. In the fourth Na site, Na is bonded to four Na and eight Ba atoms to form distorted NaBa8Na4 cuboctahedra that share corners with four equivalent NBa5Ca octahedra, faces with four NaBa8Na4 cuboctahedra, and faces with four NBa5Ca octahedra. The corner-sharing octahedra tilt angles range from 15–16°. There are two shorter (3.64 Å) and two longer (3.81 Å) Na–Na bond lengths. There are a spread of Na–Ba bond distances ranging from 4.03–4.44 Å. In the fifth Na site, Na is bonded to four Na and eight Ba atoms to form distorted NaBa8Na4 cuboctahedra that share corners with four equivalent NBa5Ca octahedra, faces with four equivalent NaBa8Na4 cuboctahedra, and faces with four equivalent NBa5Ca octahedra. The corner-sharing octahedral tilt angles are 15°. There are two shorter (3.55 Å) and two longer (3.81 Å) Na–Na bond lengths. There are four shorter (4.09 Å) and four longer (4.47 Å) Na–Ba bond lengths. In the sixth Na site, Na is bonded in a 12-coordinate geometry to eight Na and four Ba atoms. There are a spread of Na–Na bond distances ranging from 3.75–3.95 Å. There are a spread of Na–Ba bond distances ranging from 4.26–4.49 Å. In the seventh Na site, Na is bonded in a 11-coordinate geometry to five Na and six Ba atoms. There are a spread of Na–Ba bond distances ranging from 4.15–4.35 Å. In the eighth Na site, Na is bonded in a 10-coordinate geometry to six Na and four Ba atoms. There are two shorter (4.35 Å) and two longer (4.38 Å) Na–Ba bond lengths. In the ninth Na site, Na is bonded in a 8-coordinate geometry to seven Na and one Ba atom. The Na–Na bond length is 3.57 Å. The Na–Ba bond length is 4.17 Å. There are five inequivalent Ba sites. In the first Ba site, Ba is bonded in a single-bond geometry to seven Na and one N atom. The Ba–N bond length is 2.52 Å. In the second Ba site, Ba is bonded in a 3-coordinate geometry to six Na and three N atoms. There are a spread of Ba–N bond distances ranging from 2.75–2.83 Å. In the third Ba site, Ba is bonded in a 3-coordinate geometry to four Na and three N atoms. There are one shorter (2.79 Å) and two longer (2.81 Å) Ba–N bond lengths. In the fourth Ba site, Ba is bonded in a 3-coordinate geometry to five Na and three N atoms. There are two shorter (2.75 Å) and one longer (2.83 Å) Ba–N bond lengths. In the fifth Ba site, Ba is bonded in a single-bond geometry to eight Na and one N atom. The Ba–N bond length is 2.53 Å. Ca is bonded in an octahedral geometry to six N atoms. There are four shorter (2.57 Å) and two longer (2.58 Å) Ca–N bond lengths. There are two inequivalent N sites. In the first N site, N is bonded to five Ba and one Ca atom to form distorted NBa5Ca octahedra that share corners with two equivalent NaBa8Na4 cuboctahedra, a cornercorner with one NBa5Ca octahedra, faces with two equivalent NaBa8Na4 cuboctahedra, and faces with four equivalent NBa5Ca octahedra. The corner-sharing octahedral tilt angles are 0°. In the second N site, N is bonded to five Ba and one Ca atom to form distorted NBa5Ca octahedra that share corners with two equivalent NaBa8Na4 cuboctahedra, a cornercorner with one NBa5Ca octahedra, faces with two NaBa8Na4 cuboctahedra, and faces with four NBa5Ca octahedra. The corner-sharing octahedral tilt angles are 0°.

Explore related subjects

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

2020-04-29. Materials Data on Ba14Na21CaN6 by Materials Project. https://doi.org/10.17188/1275828

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↗