Meta-barium borate, II-BaB2O4, at 163 and 293 K.

The single-crystal X-ray diffraction structure analysis of an excellent non-linear optical material, viz. II-BaB2O4 or Ba3(B3O6)2, has been carried out at 163 and 293 K. The two sets of structural data are compared and indicate a significant shortening of the c axial length in the unit cell at 163 K, whereas the a and b axial lengths essentially do not change.