title: B-site ordered double perovskite LaBa1-xSrxZnSbO6 (0 ≤ x ≤ 1): Sr(2+)-doping-induced symmetry evolution and structure-luminescence correlations.
abstract: The study of perovskites has been active for a long time. Here, we rationally designed and prepared a double perovskite, LaBaZnSbO6, by selecting Zn(2+) and Sb(5+) with large size and charge differences, and, indeed, complete B-site ordering can be achieved. Careful study using powder X-ray diffraction data pinpointed its space group to be I2/m, which has rarely been seen in double perovskites. Thereafter, an interesting observation of Sr(2+)-doping-induced symmetry evolution from I2/m to P21/n was confirmed in the complete solid solutions LaBa1-xSrxZnSbO6, where the tilting system also transferred from a(-)a(-)c(0) to a(-)a(-)c(+). The transition boundary is around x = 0.4. It can also be visualized by the variation of θ (defined as c/[(a + b)/2]), which is associated with the anisotropic shrinkage of the unit cell lattice and indeed shows a minimum at x = 0.4. Such a successive modulation of both the structural symmetry and the average La/Ba/Sr-O bond distances (revealed by Rietveld refinements) motivated us to study the Eu(3+) luminescence in La0.95Eu0.05Ba1-xSrxZnSbO6. Interestingly, the maximum of charge transfer absorption of Eu(3+) shows a precise changing tendency with the A-O bond distances along with the Sr(2+) doping, clearly revealing the structure-luminescence correlations.
authors.affiliation: College of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400044, P. R. China. congrihong@cqu.edu.cn taoyang@cqu.edu.cn.
authors.forename: Pengfei
authors.initials: P
authors.lastname: Jiang
authors.affiliation: College of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400044, P. R. China. congrihong@cqu.edu.cn taoyang@cqu.edu.cn.
authors.forename: Zhengyang
authors.initials: Z
authors.lastname: Zhou
authors.affiliation: College of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400044, P. R. China. congrihong@cqu.edu.cn taoyang@cqu.edu.cn.
authors.forename: Wenliang
authors.initials: W
authors.lastname: Gao
authors.affiliation: College of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400044, P. R. China. congrihong@cqu.edu.cn taoyang@cqu.edu.cn.
authors.forename: Rihong
authors.initials: R
authors.lastname: Cong
authors.affiliation: College of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400044, P. R. China. congrihong@cqu.edu.cn taoyang@cqu.edu.cn.
authors.forename: Tao
authors.initials: T
authors.lastname: Yang