Search NASA⌕ Search

DOE OSTI · 1271702

Materials Data on Mg10Ge3(H2O9)2 by Materials Project

Abstract

Mg10Ge3(H2O9)2 crystallizes in the orthorhombic Pnn2 space group. The structure is three-dimensional. there are seven inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with four MgO6 octahedra, corners with two equivalent GeO4 tetrahedra, edges with two equivalent GeO6 octahedra, and edges with seven MgO6 octahedra. The corner-sharing octahedra tilt angles range from 5–16°. There are a spread of Mg–O bond distances ranging from 2.08–2.19 Å. In the second Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share a cornercorner with one GeO6 octahedra, corners with four MgO6 octahedra, a cornercorner with one GeO4 tetrahedra, an edgeedge with one GeO6 octahedra, and edges with six MgO6 octahedra. The corner-sharing octahedra tilt angles range from 1–55°. There are a spread of Mg–O bond distances ranging from 2.05–2.23 Å. In the third Mg2+ site, Mg2+ is bonded to six O2- atoms to form distorted MgO6 octahedra that share corners with five MgO6 octahedra, corners with two equivalent GeO4 tetrahedra, an edgeedge with one GeO6 octahedra, and edges with five MgO6 octahedra. The corner-sharing octahedra tilt angles range from 6–55°. There are a spread of Mg–O bond distances ranging from 2.01–2.26 Å. In the fourth Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with four MgO6 octahedra, corners with two equivalent GeO4 tetrahedra, edges with two equivalent GeO6 octahedra, and edges with seven MgO6 octahedra. The corner-sharing octahedra tilt angles range from 6–17°. There are a spread of Mg–O bond distances ranging from 2.09–2.18 Å. In the fifth Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with two equivalent MgO6 octahedra, corners with four equivalent GeO4 tetrahedra, an edgeedge with one GeO6 octahedra, and edges with five MgO6 octahedra. The corner-sharing octahedral tilt angles are 13°. There are a spread of Mg–O bond distances ranging from 2.08–2.17 Å. In the sixth Mg2+ site, Mg2+ is bonded to six O2- atoms to form distorted MgO6 octahedra that share corners with five MgO6 octahedra, corners with two equivalent GeO4 tetrahedra, an edgeedge with one GeO6 octahedra, and edges with five MgO6 octahedra. The corner-sharing octahedra tilt angles range from 5–55°. There are a spread of Mg–O bond distances ranging from 2.01–2.27 Å. In the seventh Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with two equivalent MgO6 octahedra, corners with four equivalent GeO4 tetrahedra, an edgeedge with one GeO6 octahedra, and edges with five MgO6 octahedra. The corner-sharing octahedral tilt angles are 13°. There are a spread of Mg–O bond distances ranging from 2.08–2.18 Å. There are two inequivalent Ge4+ sites. In the first Ge4+ site, Ge4+ is bonded to six O2- atoms to form GeO6 octahedra that share corners with two equivalent MgO6 octahedra and edges with twelve MgO6 octahedra. The corner-sharing octahedral tilt angles are 1°. There is four shorter (1.91 Å) and two longer (2.03 Å) Ge–O bond length. In the second Ge4+ site, Ge4+ is bonded to four O2- atoms to form GeO4 tetrahedra that share corners with eleven MgO6 octahedra. The corner-sharing octahedra tilt angles range from 52–59°. There is one shorter (1.79 Å) and three longer (1.80 Å) Ge–O bond length. There are two inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the second H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. There are nine inequivalent O2- sites. In the first O2- site, O2- is bonded to five Mg2+ and one Ge4+ atom to form OMg5Ge octahedra that share a cornercorner with one OMg5Ge octahedra, a cornercorner with one OMg3Ge trigonal pyramid, an edgeedge with one OMg5Ge octahedra, edges with six OMg4Ge square pyramids, and an edgeedge with one OMg3Ge trigonal pyramid. The corner-sharing octahedral tilt angles are 0°. In the second O2- site, O2- is bonded in a rectangular see-saw-like geometry to three Mg2+ and one Ge4+ atom. In the third O2- site, O2- is bonded in a 3-coordinate geometry to two Mg2+ and one Ge4+ atom. In the fourth O2- site, O2- is bonded in a rectangular see-saw-like geometry to three Mg2+ and one Ge4+ atom. In the fifth O2- site, O2- is bonded in a distorted single-bond geometry to three Mg2+ and one H1+ atom. In the sixth O2- site, O2- is bonded in a distorted single-bond geometry to three Mg2+ and one H1+ atom. In the seventh O2- site, O2- is bonded to three Mg2+ and one Ge4+ atom to form distorted OMg3Ge trigonal pyramids that share a cornercorner with one OMg5Ge octahedra, an edgeedge with one OMg5Ge octahedra, and edges with two OMg4Ge square pyramids. The corner-sharing octahedral tilt angles are 3°. In the eighth O2- site, O2- is bonded to four Mg2+ and one Ge4+ atom to form OMg4Ge square pyramids that share corners with two OMg4Ge square pyramids, edges with three equivalent OMg5Ge octahedra, edges with two OMg4Ge square pyramids, and an edgeedge with one OMg3Ge trigonal pyramid. In the ninth O2- site, O2- is bonded to four Mg2+ and one Ge4+ atom to form OMg4Ge square pyramids that share corners with two OMg4Ge square pyramids, edges with three equivalent OMg5Ge octahedra, edges with two OMg4Ge square pyramids, and an edgeedge with one OMg3Ge trigonal pyramid.

Explore related subjects

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

2020-04-29. Materials Data on Mg10Ge3(H2O9)2 by Materials Project. https://doi.org/10.17188/1271702

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↗