Sr10[(PO4)5.5(BO4)0.5](BO2): Growth and crystal structure of a strontium phosphate orthoborate metaborate closely related to the apatite-type crystal structure

Single crystals of the strontium phosphate orthoborate metaborate, Sr-10[(PO4)(5).(5)(BO4)(0.5)](BO2), were grown from the melt and investigated by X-ray diffraction (space group P (3) over bar No. 147, a=9 7973(8)angstrom, c=7.3056(8)angstrom, V=607.29(10)angstrom(3), Z=1) The crystal structure is closely related to apatite and contains linear metaborate groups, [BO2](-) (point group D-infinity h, B-O=1.284(11)angstrom) taking positions within the channels running along the three-fold inversion axis Strontium sites are found to be fully occupied while [PO4](3-) tetrahedra are partially replaced by [BO4](5-) groups (C) 2010 Elsevier Inc. All rights reserved