title: Structural Evolutions and Crystal Field Characterizations of Tm-Doped YAlO3: New Theoretical Insights.
abstract: The recent renaissance of the use of rare-earth-doped yttrium orthoaluminate as an ideal laser material has generated significant interest; however, the unique structural features underlying many of its outstanding optical properties still require elucidation. To solve this intriguing problem, we performed a systematic first-principles study; the results of the study reveal a new stable phase for Tm3+-doped YAlO3(YAP), of monoclinic Pm symmetry, with an 80-atom per unit cell. An unbiased CALYPSO structure search indicates that the Tm3+impurity ion tends to substitute the position of Y3+in the YAP crystal lattice. Electronic band structure calculations reveal that the insulated behaviors of YAP are significantly eliminated after doping the impure Tm3+ions, as evidenced by the minor energy gap of about 0.4 eV, which is close to the band gap energy of a 2 μm emitter source. On the basis of our developed crystal-field theory method, the 4f12electronic structures and energies of Tm3+ions in the YAP crystal are calculated. The theoretical results indicate that the electric-dipole-induced transition3H4→3H5is mainly responsible for producing the light wave at approximately 2.3 μm. The present results provide an essential understanding of the rare-earth-ion-doped lasing materials and serve as a practical tool for further exploration of such materials.
authors.affiliation: Institute of Atomic and Molecular Physics, Sichuan University , Chengdu 610065, China.|Department of Physics, Nanyang Normal University , Nanyang 473061, China.
authors.forename: Meng
authors.initials: M
authors.lastname: Ju
authors.affiliation: Department of Physics, Nanyang Normal University , Nanyang 473061, China.
authors.forename: Cheng
authors.initials: C
authors.lastname: Lu
authors.affiliation: Department of Science and Environmental Studies, The Education University of Hong Kong , 10 Lo Ping Road, Tai Po, NT, Hong Kong, China.
authors.forename: Yauyuen
authors.initials: Y
authors.lastname: Yeung
authors.affiliation: Institute of Atomic and Molecular Physics, Sichuan University , Chengdu 610065, China.
authors.forename: Xiaoyu
authors.initials: X
authors.lastname: Kuang
authors.affiliation: Institute of Atomic and Molecular Physics, Sichuan University , Chengdu 610065, China.
authors.forename: Jingjing
authors.initials: J
authors.lastname: Wang
authors.affiliation: Department of Physics, Nanyang Normal University , Nanyang 473061, China.
authors.forename: Yongsheng
authors.initials: Y
authors.lastname: Zhu
keywords: crystal field theory; crystal structures; electric dipole transitions; energy levels; first-principle calculations