SYNTHESIS AND CRYSTAL-STRUCTURE OF DI-BAR IUM POTASSIUM TRI-ZINC BORATE BA2KZN3(B3O6)(B6O13)

Single crystals of the new compound Ba2KZn3(B3O6)(B6O13) were obtained by using a B2O3 flux technique; they crystallize in an as yet unknown structure type. X-ray investigations led to the space group C-i(1)-P (1) over bar (Nr.2)with lattice parameters a = 705.2(2), b = 712.5(2), c = 1880.3(6), alpha = 93.43(3)degrees, beta = 90.72(2)degrees, gamma = 119.57(2)degrees, Z = 2. The structure contains (B3O6)(3-)-rings an d a new discrete (B6O13)(8-) anion, which is composed of two BO4 and t wo B2O5 units. Zn2+ is tetrahedrally coordinated by oxygen and two out of three tenfold coordinated Ba-sites are statistically occupied by B a2+ and K+.