Investigation of the structures and electronic properties for Ce3+doped yttrium orthoaluminate: A first-principle study

Trivalent Cerium ion (Ce3+) doped Yttrium Orthoaluminate (YAlO3) crystals (YAP:Ce) have been widely used in many kinds of fields owing to their fast scintillation, high light yield and very fantastic mechanical and chemical properties. However, the fundamental information of the structures for YAP:Ce remain an challenging topic. Therefore, we have investigated the structural evolution of YAP:Ce in detail by using the crystal structure analysis by particle swarm optimization (CALYPSO) structure search method together with the first principle calculations. The monoclinic structure with Pm space group is identified for the first time, and the results show that the impurity Ce3+ ions occupy the Y3+ sites and successfully integrate into the YAlO3 host crystal with a Ce3+ concentration of 6.25%. The simulated X-ray diffraction (XRD) patterns are greatly accordance with the experimental data, which illustrates the effectiveness of the ground-state structure. The information of electronic band structures indicates that the closure of the band gap for YAP:Ce is because of the doping of the Ce3+. The bands near the Fermi level are entirely composed of f states. These results reveal that the impurity Ce3+ ions lead to the transition of electronic feature from the insulator to the semiconductor. Through researching the electron localization function (ELF) of YAP:Ce, we can conclude that the bond characters of the Y-O and Ce-O are both ionic. Our results could provide important insights into exploring the new generation rare-earth doped laser crystals.