Engineering Papers⌕ Search

DOE OSTI · 1759626

Materials Data on KMg6Ti by Materials Project

Abstract

KMg6Ti crystallizes in the orthorhombic Amm2 space group. The structure is three-dimensional. K is bonded to ten Mg and two equivalent Ti atoms to form KMg10Ti2 cuboctahedra that share corners with four equivalent MgK2Mg10 cuboctahedra, corners with six equivalent KMg10Ti2 cuboctahedra, edges with two equivalent MgK2Mg10 cuboctahedra, edges with four equivalent TiK2Mg10 cuboctahedra, faces with two equivalent KMg10Ti2 cuboctahedra, faces with two equivalent TiK2Mg10 cuboctahedra, and faces with eight MgMg10Ti2 cuboctahedra. There are a spread of K–Mg bond distances ranging from 3.26–3.38 Å. Both K–Ti bond lengths are 3.47 Å. There are four inequivalent Mg sites. In the first Mg site, Mg is bonded in a 3-coordinate geometry to two equivalent K, six Mg, and two equivalent Ti atoms. There are a spread of Mg–Mg bond distances ranging from 3.23–3.31 Å. There are one shorter (3.02 Å) and one longer (3.54 Å) Mg–Ti bond lengths. In the second Mg site, Mg is bonded to ten Mg and two equivalent Ti atoms to form MgMg10Ti2 cuboctahedra that share corners with four equivalent TiK2Mg10 cuboctahedra, corners with six equivalent MgMg10Ti2 cuboctahedra, edges with two equivalent TiK2Mg10 cuboctahedra, edges with four equivalent MgK2Mg10 cuboctahedra, faces with two equivalent TiK2Mg10 cuboctahedra, faces with four MgMg10Ti2 cuboctahedra, and faces with six equivalent KMg10Ti2 cuboctahedra. There are two shorter (3.27 Å) and four longer (3.30 Å) Mg–Mg bond lengths. Both Mg–Ti bond lengths are 3.38 Å. In the third Mg site, Mg is bonded in a 11-coordinate geometry to two equivalent K, seven Mg, and two equivalent Ti atoms. There are a spread of Mg–Mg bond distances ranging from 3.08–3.29 Å. Both Mg–Ti bond lengths are 3.11 Å. In the fourth Mg site, Mg is bonded to two equivalent K and ten Mg atoms to form distorted MgK2Mg10 cuboctahedra that share corners with four equivalent KMg10Ti2 cuboctahedra, corners with six equivalent MgK2Mg10 cuboctahedra, edges with two equivalent KMg10Ti2 cuboctahedra, edges with four equivalent MgMg10Ti2 cuboctahedra, faces with two equivalent KMg10Ti2 cuboctahedra, faces with four MgMg10Ti2 cuboctahedra, and faces with six equivalent TiK2Mg10 cuboctahedra. Ti is bonded to two equivalent K and ten Mg atoms to form TiK2Mg10 cuboctahedra that share corners with four equivalent MgMg10Ti2 cuboctahedra, corners with six equivalent TiK2Mg10 cuboctahedra, edges with two equivalent MgMg10Ti2 cuboctahedra, edges with four equivalent KMg10Ti2 cuboctahedra, faces with two equivalent KMg10Ti2 cuboctahedra, faces with two equivalent TiK2Mg10 cuboctahedra, and faces with eight MgMg10Ti2 cuboctahedra.

Explore related subjects

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

2020-09-03. Materials Data on KMg6Ti by Materials Project. https://doi.org/10.17188/1759626

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↗