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The structures of polonium and its compounds—I α and β polonium metal

1966; Pergamon Press; Volume: 28; Issue: 9 Linguagem: Inglês

10.1016/0022-1902(66)80270-1

1878-1225

R.J. DeSando, Robert Lange,

X-ray Diffraction in Crystallography

Employing an isotopic mixture of Po208 and Po209 the crystal structures of alpha and beta polonium metal were redetermined from X-ray diffraction powder photographs using monochromatic radiation and a helium atmosphere. Electron distribution curves as a function of interatomic distance were also computed. Previous X-ray data obtained from Po210 (half-life of 138·4 days), were influenced by the growth of lead at the rate of 0·5 per cent per day and self heating effects. The half-lives of Po208 and Po209 are 2·8 years and 103 yr, respectively. The growth rate of lead and the thermal effects from self heating are reduced to four per cent of those in Po210. Alpha polonium is simple cubic and in space group Pm3m with a = 3·359 ± 0·001 Å and ϱX-ray = 9·142 g/cm3. Beta polonium is rhombohedral and in space group R3m (A10 type) with a = 3·368 ± 0·001 Å, α = 98° 14·4′ and ϱX-ray 9·.392 g/cm3. The structure of polonium and its relationship to elements in Group VIB are discussed.