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Stability of the different AlOOH phases under pressure
Andrés Cedillo1, Marc Torrent, Pietro Cortona
1Departamento de Química, Universidad Autónoma Metropolitana-Iztapalapa, San Rafael Atlixco 186, México DF, Mexico.
Summary
Density functional theory reveals that GGAsol functionals are essential for accurately predicting aluminum oxyhydroxide (AlOOH) phase stability and hydrogen bonding under pressure. This work details pressure-induced hydrogen bond symmetrization in specific AlOOH phases.
Area of Science:
- Materials Science
- Solid-State Physics
- Computational Chemistry
Background:
- Aluminum oxyhydroxide (AlOOH) exists in multiple crystalline phases (α, γ, δ) with distinct properties.
- Understanding phase stability and structural evolution under pressure is crucial for materials applications.
- Previous studies may lack accurate theoretical descriptions of hydrogen bonding and phase transitions.
Purpose of the Study:
- To systematically investigate the pressure-dependent behavior of α, γ, and δ-AlOOH phases.
- To evaluate the performance of various density functional theory (DFT) functionals in describing these phases.
- To elucidate the evolution of hydrogen bonds and phase stability under high compression.
Main Methods:
- Utilizing density functional theory (DFT) calculations.
- Employing various exchange-correlation functionals: local, generalized gradient approximation (GGA), and GGA for solids (GGAsol).
- Analyzing phase stability, compressibility, and hydrogen bond characteristics from 0 to 30 GPa.
Main Results:
- GGAsol functionals are mandatory for correct phase stability order and accurate lattice parameters.
- Pressure-induced hydrogen bond symmetrization observed in γ and δ-AlOOH phases at high pressures.
- α-AlOOH phase exhibits persistent hydrogen bond asymmetry under compression.
Conclusions:
- GGAsol functionals provide superior accuracy for AlOOH phase stability and hydrogen bonding compared to local and GGA functionals.
- The study clarifies pressure-induced structural transitions and hydrogen bond evolution in AlOOH polymorphs.
- Accurate theoretical modeling is vital for understanding materials under extreme conditions.
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