title: KBa7Mg2B14O28F5, a new borate with an unusual heptaborate group and double perovskite unit.
abstract: A new borate, potassium barium magnesium borate fluoride, KBa(7)Mg(2)B(14)O(28)F(5), with a nominal 7:1 composition of BaB(2)O(4) to KMg(2)F(5), has been found during the growth of BaMgBO(3)F crystals with a KF flux. It crystallized in the space group C2/c and is composed of isolated heptaborate [B(7)O(14)](7-) groups and double perovskite [Mg(2)O(6)F(5)](13-) units.
authors.affiliation: Beijing Center for Crystal Research and Development, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, People's Republic of China. rkli@mail.ipc.ac.cn
authors.forename: R K
authors.initials: RK
authors.lastname: Li
authors.forename: Peng
authors.initials: P
authors.lastname: Chen