Compositional-Dependent Structural Parameters and Energetics of Hibonite: Quantum-Chemical Investigation
Mhamed Ali Guerch1, Mubeen Jawed1, Ghaus Tariq1
1School of Science, Engineering and Technology, Pennsylvania State University─Harrisburg, 777 W. Harrisburg Pike, Middletown, Pennsylvania 17057, United States.
The Journal of Physical Chemistry. A
|July 8, 2024
Summary
Hibonite crystal structure expands with titanium and magnesium substitutions. This substitution increases hibonite mineral stability, crucial for understanding early solar system materials.
Area of Science:
- Mineralogy
- Materials Science
- Planetary Science
Background:
- Hibonite (CaAl12O19) is an early-condensing mineral from the solar nebula with a hexagonal structure.
- Hibonite features five distinct aluminum cation sites (M1-M5).
- Substitutions by transition metals like titanium (Ti) and magnesium (Mg) alter hibonite's properties.
Purpose of the Study:
- To investigate the impact of Ti and Mg substitutions on hibonite's lattice parameters.
- To explore the relationship between substitution type, cation site, and unit cell expansion.
- To determine how substitutions affect the energetic stability of hibonite.
Main Methods:
- Density Functional Theory (DFT)-based calculations were employed.
- Simulations focused on single (Al -> Ti3+) and double (2Al -> Ti4+ + Mg2+) substitution mechanisms.
- Analysis of changes in unit cell parameters (a and c) and lattice energy.
Main Results:
- Both single and double substitutions lead to an increase in hibonite's unit cell parameters (a and c).
- The extent of lattice expansion varies depending on the specific cation site (M1-M5) and substitution type.
- Substituted hibonite gains energy and stability compared to unsubstituted structures, with site-dependent variations.
Conclusions:
- Substitution of Al by Ti and Mg demonstrably expands the hibonite unit cell.
- The energetic stabilization resulting from substitution is linked to lattice expansion and specific cation site occupation.
- These findings provide insights into hibonite's behavior and evolution in early solar system conditions.
Related Concept Videos
01:16IR Spectroscopy: Hooke's Law Approximation of Molecular Vibration
1.3K
A covalently bonded heteronuclear diatomic molecule can be modeled as two vibrating masses connected by a spring. The vibrational frequency of the bond can be expressed using an equation derived from Hooke's law, which describes how the force applied to stretch or compress a spring is proportional to the displacement of the spring. In this case, the atoms behave like masses, and the bond acts like a spring.
According to Hooke's law, the vibrational frequency is directly proportional to...
According to Hooke's law, the vibrational frequency is directly proportional to...
1.3K
02:46Crystal Field Theory - Tetrahedral and Square Planar Complexes
42.0K
Tetrahedral Complexes
Crystal field theory (CFT) is applicable to molecules in geometries other than octahedral. In octahedral complexes, the lobes of the dx2−y2 and dz2 orbitals point directly at the ligands. For tetrahedral complexes, the d orbitals remain in place, but with only four ligands located between the axes. None of the orbitals points directly at the tetrahedral ligands. However, the dx2−y2 and dz2 orbitals (along the Cartesian axes) overlap with the ligands less than the dxy,...
Crystal field theory (CFT) is applicable to molecules in geometries other than octahedral. In octahedral complexes, the lobes of the dx2−y2 and dz2 orbitals point directly at the ligands. For tetrahedral complexes, the d orbitals remain in place, but with only four ligands located between the axes. None of the orbitals points directly at the tetrahedral ligands. However, the dx2−y2 and dz2 orbitals (along the Cartesian axes) overlap with the ligands less than the dxy,...
42.0K
02:16Resonance and Hybrid Structures
16.8K
According to the theory of resonance, if two or more Lewis structures with the same arrangement of atoms can be written for a molecule, ion, or radical, the actual distribution of electrons is an average of that shown by the various Lewis structures.
Resonance Structures and Resonance Hybrids
The Lewis structure of a nitrite anion (NO2−) may actually be drawn in two different ways, distinguished by the locations of the N–O and N=O bonds.
Resonance Structures and Resonance Hybrids
The Lewis structure of a nitrite anion (NO2−) may actually be drawn in two different ways, distinguished by the locations of the N–O and N=O bonds.
16.8K
02:44The Born-Haber Cycle
21.8K
Lattice Energy
21.8K
02:42Valence Bond Theory
8.5K
Coordination compounds and complexes exhibit different colors, geometries, and magnetic behavior, depending on the metal atom/ion and ligands from which they are composed. In an attempt to explain the bonding and structure of coordination complexes, Linus Pauling proposed the valence bond theory, or VBT, using the concepts of hybridization and the overlapping of the atomic orbitals. According to VBT, the central metal atom or ion (Lewis acid) hybridizes to provide empty orbitals of suitable...
8.5K
02:58Crystal Field Theory - Octahedral Complexes
26.3K
Crystal Field Theory
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
26.3K