Search NASA⌕ Search

DOE OSTI · 1704238

Materials Data on K6Mo7O34 by Materials Project

Abstract

K6Mo7O34 crystallizes in the orthorhombic Ama2 space group. The structure is three-dimensional. there are four inequivalent K sites. In the first K site, K is bonded in a 8-coordinate geometry to eight O atoms. There are a spread of K–O bond distances ranging from 2.83–2.94 Å. In the second K site, K is bonded in a 8-coordinate geometry to eight O atoms. There are a spread of K–O bond distances ranging from 2.62–3.16 Å. In the third K site, K is bonded in a 8-coordinate geometry to eight O atoms. There are a spread of K–O bond distances ranging from 2.67–3.23 Å. In the fourth K site, K is bonded in a 7-coordinate geometry to seven O atoms. There are a spread of K–O bond distances ranging from 2.66–3.38 Å. There are four inequivalent Mo sites. In the first Mo site, Mo is bonded to seven O atoms to form distorted MoO7 pentagonal bipyramids that share a cornercorner with one OK2MoO tetrahedra. There are a spread of Mo–O bond distances ranging from 1.74–2.29 Å. In the second Mo site, Mo is bonded in a 6-coordinate geometry to six O atoms. There are a spread of Mo–O bond distances ranging from 1.78–2.37 Å. In the third Mo site, Mo is bonded in a 6-coordinate geometry to six O atoms. There are a spread of Mo–O bond distances ranging from 1.75–2.32 Å. In the fourth Mo site, Mo is bonded in a 6-coordinate geometry to six O atoms. There are a spread of Mo–O bond distances ranging from 1.75–2.33 Å. There are twenty inequivalent O sites. In the first O site, O is bonded to two K, one Mo, and one O atom to form distorted OK2MoO tetrahedra that share a cornercorner with one MoO7 pentagonal bipyramid, a cornercorner with one OK2MoO tetrahedra, and a cornercorner with one OMo4 trigonal pyramid. The O–O bond length is 1.39 Å. In the second O site, O is bonded in a 3-coordinate geometry to one K, one Mo, and one O atom. In the third O site, O is bonded in a water-like geometry to two Mo atoms. In the fourth O site, O is bonded in a distorted single-bond geometry to two K and one Mo atom. In the fifth O site, O is bonded to four Mo atoms to form distorted OMo4 trigonal pyramids that share a cornercorner with one OK2MoO tetrahedra and a cornercorner with one OMo4 trigonal pyramid. In the sixth O site, O is bonded in a 3-coordinate geometry to one K and two Mo atoms. In the seventh O site, O is bonded in a distorted trigonal non-coplanar geometry to one K and two Mo atoms. In the eighth O site, O is bonded in a distorted trigonal non-coplanar geometry to three Mo atoms. In the ninth O site, O is bonded in a distorted rectangular see-saw-like geometry to one K and three Mo atoms. In the tenth O site, O is bonded in a 1-coordinate geometry to two K and one Mo atom. In the eleventh O site, O is bonded in a bent 120 degrees geometry to two equivalent Mo atoms. In the twelfth O site, O is bonded in a 1-coordinate geometry to two K and one Mo atom. In the thirteenth O site, O is bonded in a 1-coordinate geometry to two K and one Mo atom. In the fourteenth O site, O is bonded in a bent 120 degrees geometry to two equivalent Mo atoms. In the fifteenth O site, O is bonded in a distorted bent 120 degrees geometry to one K and one Mo atom. In the sixteenth O site, O is bonded in a distorted T-shaped geometry to three K atoms. In the seventeenth O site, O is bonded in a bent 120 degrees geometry to two equivalent O atoms. Both O–O bond lengths are 1.31 Å. In the eighteenth O site, O is bonded in a bent 120 degrees geometry to two K atoms. In the nineteenth O site, O is bonded in an L-shaped geometry to two K atoms. In the twentieth O site, O is bonded in a 4-coordinate geometry to three K and one O atom.

Explore related subjects

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

2020-04-29. Materials Data on K6Mo7O34 by Materials Project. https://doi.org/10.17188/1704238

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↗