Na5AsO5 was prepared from a mixture of Na2O and Na4As2O7 by solid state rea
ction at 500 degreesC in closed silver crucibles. The crystal structure (X-
ray powder data, profilematching: Pbcm, a = 596.4(1). b = 1643.3(1), c = 64
2,1(1)pm, Z = 4. R-p = 0.0764- R-wp = 0.1019) shows unchanged AsO43--tetrah
edra and strings of cis-condensed ONa6-octahedra. IR and Raman data are giv
en.