Search NASA⌕ Search

DOE OSTI · 1696565

Materials Data on Sm7Ti4(Se2O)6 by Materials Project

Abstract

Sm7Ti4(Se2O)6 crystallizes in the monoclinic Cm space group. The structure is three-dimensional. there are seven inequivalent Sm+2.86+ sites. In the first Sm+2.86+ site, Sm+2.86+ is bonded in a 3-coordinate geometry to five Se2- and three O2- atoms. There are a spread of Sm–Se bond distances ranging from 2.95–3.13 Å. There are two shorter (2.38 Å) and one longer (2.51 Å) Sm–O bond lengths. In the second Sm+2.86+ site, Sm+2.86+ is bonded in a 3-coordinate geometry to five Se2- and three O2- atoms. There are three shorter (3.05 Å) and two longer (3.14 Å) Sm–Se bond lengths. There are two shorter (2.31 Å) and one longer (2.39 Å) Sm–O bond lengths. In the third Sm+2.86+ site, Sm+2.86+ is bonded in a 9-coordinate geometry to six Se2- and three O2- atoms. There are a spread of Sm–Se bond distances ranging from 2.98–3.19 Å. There are two shorter (2.45 Å) and one longer (2.59 Å) Sm–O bond lengths. In the fourth Sm+2.86+ site, Sm+2.86+ is bonded in a 3-coordinate geometry to six Se2- and three O2- atoms. There are a spread of Sm–Se bond distances ranging from 3.15–3.24 Å. There are two shorter (2.35 Å) and one longer (2.41 Å) Sm–O bond lengths. In the fifth Sm+2.86+ site, Sm+2.86+ is bonded in a 3-coordinate geometry to five Se2- and three O2- atoms. There are a spread of Sm–Se bond distances ranging from 2.93–3.35 Å. There are two shorter (2.42 Å) and one longer (2.47 Å) Sm–O bond lengths. In the sixth Sm+2.86+ site, Sm+2.86+ is bonded in a 3-coordinate geometry to five Se2- and three O2- atoms. There are a spread of Sm–Se bond distances ranging from 3.02–3.24 Å. There are two shorter (2.35 Å) and one longer (2.42 Å) Sm–O bond lengths. In the seventh Sm+2.86+ site, Sm+2.86+ is bonded in a 7-coordinate geometry to seven Se2- atoms. There are a spread of Sm–Se bond distances ranging from 2.89–3.17 Å. There are four inequivalent Ti4+ sites. In the first Ti4+ site, Ti4+ is bonded to five Se2- and one O2- atom to form distorted edge-sharing TiSe5O octahedra. There are a spread of Ti–Se bond distances ranging from 2.44–2.66 Å. The Ti–O bond length is 1.97 Å. In the second Ti4+ site, Ti4+ is bonded in a distorted single-bond geometry to five Se2- and one O2- atom. There are a spread of Ti–Se bond distances ranging from 2.56–2.72 Å. The Ti–O bond length is 1.85 Å. In the third Ti4+ site, Ti4+ is bonded in a distorted linear geometry to four Se2- and two O2- atoms. There are two shorter (2.66 Å) and two longer (2.68 Å) Ti–Se bond lengths. Both Ti–O bond lengths are 1.92 Å. In the fourth Ti4+ site, Ti4+ is bonded in a distorted linear geometry to four Se2- and two O2- atoms. There are two shorter (2.61 Å) and two longer (2.68 Å) Ti–Se bond lengths. There is one shorter (1.92 Å) and one longer (1.96 Å) Ti–O bond length. There are twelve inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 6-coordinate geometry to four Sm+2.86+ and two equivalent Ti4+ atoms. In the second Se2- site, Se2- is bonded in a 2-coordinate geometry to three Sm+2.86+ and two equivalent Ti4+ atoms. In the third Se2- site, Se2- is bonded in a 2-coordinate geometry to three Sm+2.86+ and two equivalent Ti4+ atoms. In the fourth Se2- site, Se2- is bonded in a 5-coordinate geometry to three Sm+2.86+ and two equivalent Ti4+ atoms. In the fifth Se2- site, Se2- is bonded in a 5-coordinate geometry to three Sm+2.86+ and two equivalent Ti4+ atoms. In the sixth Se2- site, Se2- is bonded in a 5-coordinate geometry to three Sm+2.86+ and two equivalent Ti4+ atoms. In the seventh Se2- site, Se2- is bonded in a 4-coordinate geometry to three Sm+2.86+ and two equivalent Ti4+ atoms. In the eighth Se2- site, Se2- is bonded in a 4-coordinate geometry to two Sm+2.86+ and two equivalent Ti4+ atoms. In the ninth Se2- site, Se2- is bonded in a 3-coordinate geometry to two equivalent Sm+2.86+ and one Ti4+ atom. In the tenth Se2- site, Se2- is bonded in a 5-coordinate geometry to four Sm+2.86+ and one Ti4+ atom. In the eleventh Se2- site, Se2- is bonded in a 5-coordinate geometry to five Sm+2.86+ atoms. In the twelfth Se2- site, Se2- is bonded in a 4-coordinate geometry to four Sm+2.86+ atoms. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded to three Sm+2.86+ and one Ti4+ atom to form a mixture of distorted corner and edge-sharing OSm3Ti tetrahedra. In the second O2- site, O2- is bonded to three Sm+2.86+ and one Ti4+ atom to form a mixture of corner and edge-sharing OSm3Ti tetrahedra. In the third O2- site, O2- is bonded to three Sm+2.86+ and one Ti4+ atom to form a mixture of distorted corner and edge-sharing OSm3Ti tetrahedra. In the fourth O2- site, O2- is bonded to three Sm+2.86+ and one Ti4+ atom to form a mixture of distorted corner and edge-sharing OSm3Ti tetrahedra. In the fifth O2- site, O2- is bonded to three Sm+2.86+ and one Ti4+ atom to form a mixture of distorted corner and edge-sharing OSm3Ti tetrahedra. In the sixth O2- site, O2- is bonded to three Sm+2.86+ and one Ti4+ atom to form a mixture of distorted corner and edge-sharing OSm3Ti tetrahedra.

Explore related subjects

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

2020-05-02. Materials Data on Sm7Ti4(Se2O)6 by Materials Project. https://doi.org/10.17188/1696565

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↗