title: Structure and distortion of lead fluoride nanocrystals in rare earth doped oxyfluoride glass ceramics.
abstract: A series of rare earth (RE) doped oxyfluoride glasses with the composition of (45-x) SiO2-5Al2O3-40PbF2-10CdF2-xRe2O3 (x = 1, 5, 10, 15) (mol%) were prepared by a traditional melt-quenching method. Glass ceramics (GCs) were obtained after thermal treatment and characterized by X-ray diffraction (XRD) to investigate the nanocrystal structure and distortion. Both the dopant type and the doping level play an important role in the distortion of the PbF2-RE lattice. It is found that a cubic Pb3REF9 phase forms in low doping GCs, a tetragonal PbREF5 phase forms in middle doping GCs and cubic PbRE3F11 forms in high doping GCs. Accordingly, the site symmetry of RE(3+) dopants in β-PbF2 nanocrystal undergoes a transition of Oh···D4h···Oh with the increase of doping level. The change in the ligands coordinating the RE(3+) ions was further illustrated by the optical changes in Yb-doped GCs. This paper provides insights on the nanocrystal structure of RE at the atomic level and tries to make a complete description of the nanocrystal structure and distortion in these glass-ceramic materials, which will benefit the optimization of optical properties.
authors.affiliation: The Key Lab of Weak Light Nonlinear Photonics, Ministry of Education, Hongda Street 23, Tianjin, 300457, China. zhaolj@nankai.edu.cn.
authors.forename: Jin
authors.initials: J
authors.lastname: Ge
authors.forename: Lijuan
authors.initials: L
authors.lastname: Zhao
authors.forename: Hui
authors.initials: H
authors.lastname: Guo
authors.forename: Zijian
authors.initials: Z
authors.lastname: Lan
authors.forename: Lifen
authors.initials: L
authors.lastname: Chang
authors.forename: Yiming
authors.initials: Y
authors.lastname: Li
authors.forename: Hua
authors.initials: H
authors.lastname: Yu