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An investigation of polyhedral deformation in two mixed‐metal diarsenates: SrZnAs 2 O 7 and BaCuAs 2 O 7
Author(s) -
Kovač Sabina,
Karanović Ljiljana,
Đorđević Tamara
Publication year - 2015
Publication title -
acta crystallographica section c
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.304
H-Index - 17
ISSN - 2053-2296
DOI - 10.1107/s2053229615005616
Subject(s) - isostructural , crystallography , barium , strontium , zinc , group (periodic table) , crystal structure , metal , copper , chemistry , diffraction , divalent , hydrothermal circulation , materials science , physics , inorganic chemistry , geology , metallurgy , organic chemistry , optics , seismology
Two isostructural diarsenates, SrZnAs 2 O 7 (strontium zinc diarsenate), (I), and BaCuAs 2 O 7 [barium copper(II) diarsenate], (II), have been synthesized under hydrothermal conditions and characterized by single‐crystal X‐ray diffraction. The three‐dimensional open‐framework crystal structure consists of corner‐sharing M 2O 5 ( M 2 = Zn or Cu) square pyramids and diarsenate (As 2 O 7 ) groups. Each As 2 O 7 group shares its five corners with five different M 2O 5 square pyramids. The resulting framework delimits two types of tunnels aligned parallel to the [010] and [100] directions where the large divalent nine‐coordinated M 1 ( M 1 = Sr or Ba) cations are located. The geometrical characteristics of the M 1O 9 , M 2O 5 and As 2 O 7 groups of known isostructural diarsenates, adopting the general formula M 1 II M 2 II As 2 O 7 ( M 1 II = Sr, Ba, Pb; M 2 II = Mg, Co, Cu, Zn) and crystallizing in the space group P 2 1 / n , are presented and discussed.