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Abnormal Site Preference of Al and Ga in Gd 3 Al 2.3 Ga 2.7 O 12 :Ce Crystals
Author(s) -
Li Mingqing,
Meng Meng,
Chen Jie,
Sun Yiyang,
Cheng Guofeng,
Chen Lu,
Zhao Shuwen,
Wan Bo,
Feng He,
Ren Guohao,
Ding Dongzhou
Publication year - 2021
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.202000603
Subject(s) - octahedron , ion , tetrahedron , crystallography , ionic radius , coordination number , crystal structure , crystal (programming language) , materials science , density functional theory , rietveld refinement , chemistry , computational chemistry , organic chemistry , computer science , programming language
Large‐sized Gd 3 Al 2.3 Ga 2.7 O 12 :Ce single crystals are grown by the Czochralski method. The distribution of Al and Ga at octahedral (oct‐, 6‐oxygen‐coordinated) and tetrahedral (tet‐, 4‐oxygen‐coordinated) sites in the crystal is studied. Rietveld refinement is used to analyze the site occupation of Al and Ga. The results show that Ga ions with a larger radius than Al ions prefer to occupy the more compact tetrahedral sites. Density functional theory calculations show that the energy for a Ga ion at the tetrahedral site is lower than that at the octahedral site in the Gd 3 Al 5 O 12 crystal, whereas the case for Al occupation in the Gd 3 Ga 5 O 12 crystal is opposite. Slater rules are used to estimate the effective charge number of different ions, and the distribution of coordination ions around the octahedral and tetrahedral sites is analyzed. Then, the interaction between ions is simplified and the repulsive energy between Al/Ga and the coordination ions is calculated, which could provide reasonable understanding on the abnormal occupation. In addition, the occupation of Sc in Gd/Y garnet systems is also discussed using this method.