Phase transformations of polymeric CdI2-type IrTe2 under high pressure

The high-pressure behavior of IrTe2 has been studied up to 32 GPa in a diam ond anvil cell by angle-dispersive X-ray diffraction at room temperature. T he CdI2-type structure was present over the whole pressure range investigat ed. At about 5 GPa, a new monoclinic phase appeared; however, the transform ation remained incomplete. At 20 GPa, new and faint diffraction lines were detected: after laser heating at this pressure, these lines increased stron gly in intensity and were easily assigned to a cubic unit cell. This phase was retained down to ambient conditions. Its structure was refined by Rietv eld analysis. It is pyrite like with Te-Te pairs. Under ambient conditions, the intrapair Te-Te distance is 3.075 Angstrom, which is much shorter than the shortest Te-Te distance in the CdI2-type phase; this distance did not decrease appreciably with pressure in contrast to interpair distances. (C) 1999 Elsevier Science Ltd. All rights reserved.