Crystal structure of element 43

Excellent powder diffraction patterns have been obtained from microgram quantities of the long-lived isotope, Tc⁹⁹, of element 43. Like rhenium, osmium and ruthenium, technetium crystallizes in the hexagonal close-packed arrangement. The cell, which contains two atoms, has the following dimensions: a₁ = 2.735 ± 0.001 A., a₃ = 4.388 ± 0.001 A., a₃/a₁ = l.604. The calculated density, based on an atomic weight of 99, is 11.497 g.cm^-3. Each atom has twelve neighbors, six at 2.735 A. and six at 2.698 A.