Metamict zircon formed by heavy ion bombardment

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Abstract
Zirconium silicate powder is converted into a range of metamict conditions, and finally to a non-crystalline condition by Argon or Krypton ion bombardment of energies of 1 to 3.5 MeV. The non-crystalline condition is induced by approximately 2 × 1015 ions per cm2. Further irradiation causes the non-crystalline particles to bloat into extended disc shapes. The glassy metamict state creeps under heavy ion irradiation. Under comparable conditions, silicates such as a-quartz bloat into a similar range of glassy shapes, whereas nitrides such as Si3N4 do not. The metamict state is essentially a glass-type random atomic structural arrangement. This formation of extended glassy shapes under ionic bombardment is an alternative method of formation of some of the glassy constituents of chondrules, tektites and lunar agglutinates by cosmic irradiation. The reported sintering under fast neutron irradiation may be explained by the joining of neighboring particles under glassy irradiation creep.