Concentration effects on the microstructures and electronic features of Nd[formula omitted]Y[formula omitted]AlO3 crystals: A first-principles study

Abstract

Nd3＋ doped YAP has attracted considerable attention because it shows promise for use in solid-state lasers and medical care. However, the microstructures underlying the electronic features with various dopant concentrations are still unclear. In this study, we carried out first-principles calculations on the microstructures of NdxY1−xAlO3 crystals (x = 0.25, 0.125, 0.0625 and 0.03125). Based on density functional theory and the particle swarm optimization algorithm, the four ground state structures for each concentration of NdxY1−xAlO3 were shown to adopt monoclinic phases. The peak values of the diffraction angles showed distinct shifts, and the subshell orbitals that most affected the lower bands varied as the dopant concentration changed. The validities of these structures were confirmed by the good agreement between the calculated X-ray diffraction (XRD) patterns and the experimental patterns. Moreover, the electronic band structures of NdxY1−xAlO3 were meticulously analysed. The conduction bands of the four structures all broke through the Fermi levels, suggesting that the doped systems were all conductors. By calculating the crystal structure electron localization function (ELF), we determined that both the Nd-O and Y-O bonds in NdxY1−xAlO3 are ionic. These results fill the small gaps in microstructure research and reveal the commonalities and individualities of the physical features formed in NdxY1−xAlO3 with different dopant concentrations, which will provide inspiration for designing luminescent materials in the future.