Synthesis and crystal structure of a novel pentaborate, Na3ZnB5O10

A novel ternary borate, trisodium zinc pentaborate, Na3ZnB5O10, has been prepared by solid-state reaction at temperature below 750 °C. The single-crystal X-ray structural analysis showed that Na3ZnB5O10 crystallizes in the monoclinic space group P21/n with a=6.6725(7) Å, b=18.1730(10) Å, c=7.8656(9) Å, β=114.604(6)°, Z=4. It represents a new structure type in which double ring [B5O10]5− building units are bridged by ZnO4 tetrahedra through common O atoms to form a two-dimensional image-layer that affords one-dimensional channels running parallel to the [101] direction. Symmetry-center related image layers are stacked along the b-axis, with the interlayer void spaces and intralayer open channels filled by Na+ cations to balance charge. The IR spectrum further confirms the presence of both BO3 and BO4 groups and UV–vis diffuse reflectance spectrum shows a band gap of about 3.2 eV.