June 2010 issue
Cover illustration: Next to orthorhombic -SrB4O7, trigonal -SrB4O7 is the second polymorph of this composition. Whereas the borate frameworkof -SrB4O7 is solely composed of corner-sharing BO4 tetrahedra, in -SrB4O7 it is made up of BO3 triangles and BO4 tetrahedra in a 1:1 ratio, leading to a considerably lower density for the -polymorph. The Sr2+ cations are located in channels running parallel to . See Vasiliev, Cherepakhin & Zaitsev [Acta Cryst. (2010). E66, i48].