title: Cs7Nd11(SeO3)12Cl16: first noncentrosymmetric structure among alkaline-metal lanthanide selenite halides.
abstract: Cs7Nd11(SeO3)12Cl16, the complex selenite chloride of cesium and neodymium, was synthesized in the NdOCl-SeO2-CsCl system. The compound has been characterized using single-crystal X-ray diffraction, electron diffraction, transmission electron microscopy, luminescence spectroscopy, and second-harmonic-generation techniques. Cs7Nd11(SeO3)12Cl16 crystallizes in an orthorhombic unit cell with a = 15.911(1) Å, b = 15.951(1) Å, and c = 25.860(1) Å and a noncentrosymmetric space group Pna2(1) (No. 33). The crystal structure of Cs7Nd11(SeO3)12Cl16 can be represented as a stacking of Nd11(SeO3)12 lamellas and CsCl-like layers. Because of the layered nature of the Cs7Nd11(SeO3)12Cl16 structure, it features numerous planar defects originating from occasionally missing the CsCl-like layer and violating the perfect stacking of the Nd11(SeO3)12 lamellas. Cs7Nd11(SeO3)12Cl16 represents the first example of a noncentrosymmetric structure among alkaline-metal lanthanide selenite halides. Cs7Nd11(SeO3)12Cl16 demonstrates luminescence emission in the near-IR region with reduced efficiency due to a high concentration of Nd(3+) ions causing nonradiative cross-relaxation.
authors.affiliation: Department of Chemistry, Moscow State University, Leninskie Gory 1 build, 3 GSP-1, 119991 Moscow, Russia. berdonosov@inorg.chem.msu.ru
authors.forename: Peter S
authors.initials: PS
authors.lastname: Berdonosov
authors.forename: Lev
authors.initials: L
authors.lastname: Akselrud
authors.forename: Yurii
authors.initials: Y
authors.lastname: Prots
authors.forename: Artem M
authors.initials: AM
authors.lastname: Abakumov
authors.forename: Philippe F
authors.initials: PF
authors.lastname: Smet
authors.forename: Dirk
authors.initials: D
authors.lastname: Poelman
authors.forename: Gustaaf
authors.initials: G
authors.lastname: Van Tendeloo
authors.forename: Valery A
authors.initials: VA
authors.lastname: Dolgikh