K4BI2O5, A NOVEL TERNARY OXOBISMUTHATE(III)

K4Bi2O5 has been synthesized as a new phase in the system K2O/Bi2O3, T he nem potassium bismuth oxide crystallizes in space group P (1) over bar With the lattice parameters a = 569.3(2), b = 952.8(4), c = 978.6( 2) pm, alpha = 186.47(2), beta = 105.06(2), and gamma = 106.42(3)degre es Z = 2. The crystal structure determination (2626 diffractometer dat a, R-1 = 0.039) reveals isolated molecule anions Bi4O108- (site symmet ry (1) over bar), Which consist of subunits in the sequence [BiO33--Bi -2(-)-BiO2--BiO33-]. So the new compound can be regarded as a mixed or tho/metabismuthate, The cations form almost regular cubic face centere d subcells. (C) 1998 Academic Press.