Structural properties and 4f → 5d absorptions in Ce-doped LuAlO₃: a first-principles study

Area of Science:

• Computational Materials Science
• Solid-State Physics
• Quantum Chemistry

Background:

• Cerium (Ce)-doped materials are of interest for their unique optical and electronic properties.
• Understanding the local atomic and electronic structure of dopants is crucial for material design.
• LuAlO(3) is a host material where Ce doping can modify its properties.

Purpose of the Study:

• To investigate the structural distortions induced by Ce doping in LuAlO(3).
• To study the 4f → 5d electronic absorptions of Ce-doped LuAlO(3).
• To determine the electronic structure and the role of electron-electron interactions (U) and spin-orbit effects.

Main Methods:

• Density functional theory (DFT) using the generalized gradient approximation PBE + U (Perdew, Burke and Ernzerhof).
• Wavefunction-based embedded cluster calculations, specifically CASSCF/CASPT2 (complete-active-space self-consistent-field/second-order perturbation theory).
• Comparison with experimental X-ray photoelectron spectroscopy (XPS) and absorption spectrum data.

Main Results:

• Ce substitution for Lu causes significant anisotropic local atomic structure distortion, largely independent of the U value for Ce 4f states.
• Electronic structures are sensitive to U, with U ≈ 6 eV determined by fitting to experimental XPS data.
• Calculated 4f → 5d transition energies and intensities agree well with experimental absorption spectra; spin-orbit effects are important for Ce 5d states.

Conclusions:

• The study elucidates the structural and electronic consequences of Ce doping in LuAlO(3) using advanced computational methods.
• The origin of the 5d(1) states is confirmed to be distinct from cubic crystal field effects.
• Accurate modeling requires considering both electron-electron interactions and spin-orbit coupling for Ce 5d states.