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Crystal Structure of AgI at 3 kbar

1968; American Institute of Physics; Volume: 48; Issue: 6 Linguagem: Inglês

10.1063/1.1669466

1520-9032

Michael J. Moore, J. S. Kasper,

High-pressure geophysics and materials

The nature of the atomic arrangement in the phase of AgI existing at pressures between 3 and 4 kbar has been deduced from x-ray diffraction studies with a diamond-anvil apparatus. The unit cell is either tetragonal or pseudotetragonal and contains a total of 4 atoms at 000, 12120, 120z, 012z̄ with z = 0.3. The calculated density is 6.19 g/cm3. While it is not possible to determine directly the site preferences of Ag and I, certain distributions are suggested by a simple displacive mechanism of producing the 3-kbar phase from the zincblende structure existing at room temperature and 1 atm pressure. The relationship of the new structure to that of the rock-salt structure existing between 4 and 100 kbar is also discussed.