title: The new pentaborate Na3SrB5O10.
abstract: Sodium strontium pentaborate, Na(3)SrB(5)O(10), maintains the same, previously unobserved, structure type at 200, 250 and 293 K. The fundamental building units are anionic [B(5)O(10)](5-) groups distorted from mm2 point symmetry. The Sr atoms are eightfold coordinated by O atoms, forming trigonal dodecahedra. The Na atoms appear in three crystallographically different environments. The present single-crystal results correct a previous report in which a monoclinic cell was deduced for this compound on the basis of powder diffraction data. The structure of the title compound is discussed in the crystalochemical context of other borates with the same formula type. Although the unit cell of the present compound is similar to that determined in a previous study of the analogous Ca-containing compound, this study demonstrates that the structures of the two are different. These novel alkali-alkaline earth borates are considered as potential host materials for optical applications (fluorescence materials or phosphors).
authors.affiliation: Institut für Kristallographie, RWTH-Aachen, Jägerstrasse 17-19, 52056 Aachen, Germany. wu@xtal.rwth-aachen.de
authors.forename: Li
authors.initials: L
authors.lastname: Wu
authors.forename: Georg
authors.initials: G
authors.lastname: Roth
authors.forename: Karine
authors.initials: K
authors.lastname: Sparta
authors.forename: Xiaolong
authors.initials: X
authors.lastname: Chen