Barium zinc diarsenate

The title compound, BaZnAs(2)O(7), belongs to the family of isotypic series of compounds adopting the general formula M1(2+) M2(2+) X (2)O(7) (M1(2+) = Ca, Sr, Ba or Pb; M2(2+) = Mg, Cr, Mn, Fe, Co, Ni, Cu, Zn or Cd; X = P or As). Suitable single crystals were prepared under hydro­thermal conditions. The framework structure is characterized by corner-sharing ZnO(5) square pyramids and As(2)O(7) groups where the Zn atoms occupy channels. X-ray diffraction analysis of single crystals twinned by non-merohedry [twin plane is (100)] yielded formula BaZnAs(2)O(7). Raman spectra confirmed the presence of a non-linear As—O—As linkage.