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DOE OSTI2020

Materials Data on KAl(SO4)2 by Materials Project

KAl(SO4)2 crystallizes in the trigonal P321 space group. The structure is three-dimensional. K1+ is bonded to twelve O2- atoms to form KO12 cuboctahedra that share edges with six equivalent KO12 cuboctahedra, edges with six equivalent SO4 tetrahedra, and faces with two equivalent AlO6 octahedra. There are six shorter (2.99 Å) and six longer (3.27 Å) K–O bond lengths. Al3+ is bonded to six equivalent O2- atoms to form AlO6 octahedra that share corners with six equivalent SO4 tetrahedra and faces with two equivalent KO12 cuboctahedra. All Al–O bond lengths are 1.90 Å. S6+ is bonded to four O2- atoms to form SO4 tetrahedra that share corners with three equivalent AlO6 octahedra and edges with three equivalent KO12 cuboctahedra. The corner-sharing octahedral tilt angles are 27°. There is one shorter (1.46 Å) and three longer (1.49 Å) S–O bond length. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 150 degrees geometry to one K1+, one Al3+, and one S6+ atom. In the second O2- site, O2- is bonded in a distorted single-bond geometry to three equivalent K1+ and one S6+ atom.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on KAl(SO4)2 by Materials Project

KAl(SO4)2 crystallizes in the trigonal P321 space group. The structure is three-dimensional. K1+ is bonded to twelve O2- atoms to form KO12 cuboctahedra that share edges with six equivalent KO12 cuboctahedra, edges with six equivalent SO4 tetrahedra, and faces with two equivalent AlO6 octahedra. There are six shorter (3.03 Å) and six longer (3.21 Å) K–O bond lengths. Al3+ is bonded to six equivalent O2- atoms to form AlO6 octahedra that share corners with six equivalent SO4 tetrahedra and faces with two equivalent KO12 cuboctahedra. All Al–O bond lengths are 1.88 Å. S6+ is bonded to four O2- atoms to form SO4 tetrahedra that share corners with three equivalent AlO6 octahedra and edges with three equivalent KO12 cuboctahedra. The corner-sharing octahedral tilt angles are 18°. There is one shorter (1.46 Å) and three longer (1.48 Å) S–O bond length. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one K1+, one Al3+, and one S6+ atom. In the second O2- site, O2- is bonded in a single-bond geometry to three equivalent K1+ and one S6+ atom.

36 MATERIALS SCIENCE↗

NASA NTRS1996

Metastable Solution Thermodynamic Properties and Crystal Growth Kinetics

The crystal growth rates of NH4H2PO4, KH2PO4, (NH4)2SO4, KAl(SO4)2 central dot 12H2O, NaCl, and glycine and the nucleation rates of KBr, KCl, NaBr central dot 2H2O, (NH4)2Cl, and (NH4)2SO4 were expressed in terms of the fundamental driving force of crystallization calculated from the activity of supersaturated solutions. The kinetic parameters were compared with those from the commonly used kinetic expression based on the concentration difference. From the viewpoint of thermodynamics, rate expressions based on the chemical potential difference provide accurate kinetic representation over a broad range of supersaturation. The rates estimated using the expression based on the concentration difference coincide with the true rates of crystallization only in the concentration range of low supersaturation and deviate from the true kinetics as the supersaturation increases.

Kim, Soojin↗

DOE OSTI2020

Materials Data on KAl(SO10)2 by Materials Project

KAlO12(SO4)2 crystallizes in the cubic Pa-3 space group. The structure is three-dimensional and consists of eight sulfuric acid molecules and one KAlO12 framework. In the KAlO12 framework, K is bonded in a distorted octahedral geometry to six equivalent O atoms. All K–O bond lengths are 3.33 Å. Al is bonded in an octahedral geometry to six equivalent O atoms. All Al–O bond lengths are 1.94 Å. There are two inequivalent O sites. In the first O site, O is bonded in a water-like geometry to one K and one O atom. The O–O bond length is 1.27 Å. In the second O site, O is bonded in a distorted bent 120 degrees geometry to one Al and one O atom.

36 MATERIALS SCIENCE↗