Crystal structures of the solid solutions Na(3)Zn(0.912)Cd(0.088)B(5)O(10) and Na(3)Zn(0.845)Mg(0.155)B(5)O(10)

Two new penta­borates, tris­odium zinc cadmium penta­borate, Na(3)Zn(0.912)Cd(0.088)B(5)O(10), and tris­odium zinc magnesium penta­borate, Na(3)Zn(0.845)Mg(0.155)B(5)O(10), have been synthesized by high-temperature solution reactions at 1023 K. Their crystal structures were determined by single-crystal X-ray diffraction. Both solid solutions crystallize in the ortho­rhom­bic form of the parent compound Na(3)ZnB(5)O(10) (space group type Pbca, Z = 8) and contain the double ring [B(5)O(10)](5−) anion composed of one BO(4) tetra­hedron and four BO(3) triangles as the basic structural motif. The anions are bridged by tetra­hedrally coordinated and occupationally disordered M (2+) (M = Zn/Cd, Zn/Mg) cations via common O atoms to form [MB(5)O(10)](n) (3n−) layers. The intra­layer inter­secting channels and the inter­layer voids are occupied by Na(+) cations to balance the charge.