A NEW QUATERNARY NITRIDE, LI3BA2NBN4

A new quaternary nitride, Li3Ba2NbN4, has been synthesized from Li, Ba, and Nb metals under flowing N2 at 850-degrees-C. The structure, as determined by single-crystal X-ray diffraction, is monoclinic, space group C2/c with Z = 4, and has lattice parameters a = 11.296(2) angstrom, b = 5.673(1) angstrom, c = 11.347(2) angstrom, and beta = 121.456(8)-degrees. Refinement based upon F2 yielded R2 = 0.073 and wR2 = 0.105. (For comparison, a refinement based upon F yielded R1 = 0.043). The Nb and one of the two independent Li ions are coordinated tetrahedrally by N anions; the Li tetrahedra are distorted. By sharing edges, the Nb and Li tetrahedra form chains which are linked by the remaining Li ions to form the three-dimensional structure. The Ba ions are located between the Li-Nb chains. (C) 1994 Academic Press, Inc.