High-pressure and high-temperature synthesis of a cubic IrO2 polymorph

✍ Scribed by Shigeaki Ono; Takumi Kikegawa; Yasuo Ohishi

• Publisher: Elsevier Science
• Year: 2005
• Tongue: English
• Weight: 297 KB
• Volume: 363
• Category: Article
• ISSN: 0921-4526
• DOI: 10.1016/j.physb.2005.03.014

✦ Synopsis

We report on in situ observations of a new cubic iridium dioxide (IrO 2 ) polymorph. Experiments were performed using a laser-heated diamond anvil cell, and high-pressure data were collected using the synchrotron X-ray diffraction method. The new high-pressure IrO 2 phase has a pyrite-type structure with space group Pa-3 and cubic symmetry. The phase was stable at pressures up to 50 GPa. The pyrite-type IrO 2 structure is the same as that exhibited by other AO 2 compounds at high pressure, such as SiO 2 , GeO 2 , and SnO 2 . The new high-pressure phase was not preserved on decompression to ambient pressure. The Birch-Murnaghan equation of state for this new cubic phase was determined from the experimental unit cell parameters, with K 0 ¼ 306 (77) GPa when the value of K 0 0 was set to K 0 0 ¼ 4. The compressibility of the cubic IrO 2 phase was in agreement with the compressibilities of other AO 2 compounds reported in the literature.