Local Structural Perturbations in HgBa2CuO4+δ

✍ Scribed by Neil C. Hyatt; Jason P. Hodges; Ian Gameson; Steve Hull; Peter P. Edwards

• Publisher: Elsevier Science
• Year: 1999
• Tongue: English
• Weight: 449 KB
• Volume: 148
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1006/jssc.1999.8391

✦ Synopsis

The high-temperature superconduct?or, HgBa 2 CuO 4؉ ( '0), is the 5rst and arguably the most simple member of the homologous series of mercury-based cuprates, of general formula HgBa 2 Ca n؊1 Cu n O 2n؉2؉ (n ‫؍‬ 1. . . 8). The presence of interstitial oxygen in the HgO rock salt layer is crucial in controlling the electronic structure of HgBa 2 CuO 4؉ . Thus, by careful control of the concentration ( ) of interstitial oxygen, one may 5ne-tune the electronic properties of this material from insulating, through superconducting, to metallic behavior. The local structure adjusts to the presence of interstitial oxygen by displacement of neighboring atoms from their 99ideal:: positions. We present here a combined powder X-ray and time-of-6ight neutron di4raction study of HgBa 2 CuO 4؉ (space group P4/mmm, lattice parameters a ‫؍‬ 3.8757(1) A s and c ‫؍‬ 9.4998(1) A s , ‫؍‬ 0.07). From this conjoint approach (powder X-ray and neutron di4raction) we are able to identify the local structural perturbations and atom displacements arising from the occupany ( ‫؍‬ 0.07) of the interstitial oxygen site in HgBa 2 CuO 4؉ .