TY - JOUR
T1 - Compositional-Dependent Structural Parameters and Energetics of Hibonite
T2 - Quantum-Chemical Investigation
AU - Guerch, Mhamed Ali
AU - Jawed, Mubeen
AU - Tariq, Ghaus
AU - Jawed, Ahsan
AU - Mistry, Milap
AU - Asaduzzaman, Abu
N1 - Publisher Copyright:
© 2024 American Chemical Society.
PY - 2024/7/18
Y1 - 2024/7/18
N2 - One of the first minerals to condense from the early solar nebula was hibonite (CaAl12O19), demonstrating a hexagonal crystal structure. There are five unique aluminum cation sites (M1-M5) in hibonite. Although hibonite contains aluminum, it can also have 3d transitional metals that substitute at aluminum cation sites, such as titanium, and other metals such as magnesium. Titanium can occur in multiple oxidation states, linking to redox conditions. A single substitution occurs when a single aluminum atom is replaced by a single titanium atom, causing the Ti to take on a 3+ oxidation state. On the other hand, Ti achieves an oxidation state of 4+ during a double substitution when a pair of aluminum atoms is replaced by a titanium and a magnesium atom. A density functional theory-based calculation is used to explore the relationship between the number of substitutions and the lattice parameters of the hibonite crystal. The calculated results reveal that the lengths of both unit cells (a and c) increase with an increasing number of single or double substitutions. The rate of increment per substitution depends on the cation sites, M1-M5, and substitution types. Along with the expansion of the unit cell of the hibonite due to the substitution, the substituted unit cell gains energy (and in turn stability) compared to the substituted unit cell without expansion, dependent on the lattice site and substitutions.
AB - One of the first minerals to condense from the early solar nebula was hibonite (CaAl12O19), demonstrating a hexagonal crystal structure. There are five unique aluminum cation sites (M1-M5) in hibonite. Although hibonite contains aluminum, it can also have 3d transitional metals that substitute at aluminum cation sites, such as titanium, and other metals such as magnesium. Titanium can occur in multiple oxidation states, linking to redox conditions. A single substitution occurs when a single aluminum atom is replaced by a single titanium atom, causing the Ti to take on a 3+ oxidation state. On the other hand, Ti achieves an oxidation state of 4+ during a double substitution when a pair of aluminum atoms is replaced by a titanium and a magnesium atom. A density functional theory-based calculation is used to explore the relationship between the number of substitutions and the lattice parameters of the hibonite crystal. The calculated results reveal that the lengths of both unit cells (a and c) increase with an increasing number of single or double substitutions. The rate of increment per substitution depends on the cation sites, M1-M5, and substitution types. Along with the expansion of the unit cell of the hibonite due to the substitution, the substituted unit cell gains energy (and in turn stability) compared to the substituted unit cell without expansion, dependent on the lattice site and substitutions.
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U2 - 10.1021/acs.jpca.4c02849
DO - 10.1021/acs.jpca.4c02849
M3 - Article
C2 - 38976356
AN - SCOPUS:85197814702
SN - 1089-5639
VL - 128
SP - 5605
EP - 5611
JO - Journal of Physical Chemistry A
JF - Journal of Physical Chemistry A
IS - 28
ER -