The Crystal Structure of Polonium by Electron Diffraction

Electron diffraction photographs (λ=0.062A) were obtained from about 10—7 g of polonium that had been volatilized in a stream of hydrogen and condensed over an area of about 3 mm2 on a thin collodion film. Diffraction patterns were also obtained from bismuth and tellurium since it was expected that polonium would have a similar crystal structure. Analysis of these patterns shows that the structure of polonium closely resembles that of tellurium, the lattice being pseudohexagonal with a=4.25A, c=7.06A, or 14.12A, and the calculated density 9.39 assuming 3 Po in the pseudo unit of structure. The true lattice is probably monoclinic with a=7.42A, b=4.29A, c=14.10A and β quite close to 90°, a suggested value being β=92°; the calculated density for 12 Po in the unit of structure is 9.24. A structure, based upon the space group C23–C2, in which each polonium atom has four nearest neighbors gives moderate agreement between observed and calculated intensities of reflection.