Heterostructured Bi-Based Cuprate High-Tc Superconductors with Unusually Coordinated Metal Halides
✍ Scribed by J.-H. Choy; Y.-I. Kim; S.-J. Hwang; I.-S. Yang
- Publisher
- Elsevier Science
- Year
- 1999
- Tongue
- English
- Weight
- 273 KB
- Volume
- 147
- Category
- Article
- ISSN
- 0022-4596
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✦ Synopsis
Attempts have been made to prepare various high-T c superconducting intercalation compounds, M+X+Bi 2 Sr 2 Ca n؊1 Cu n O 2n؉4؉ (M؍metal; X ؍ halogen; n ؍ 1, 2, and 3), with the synthetic strategy of hard+soft+acid+base interaction. The chimie douce route such as vapor transport and ionic di4usion is found to be e4ective in intercalating soft Lewis acidic guest species (I ؊ 3 , Ag x I x؊w w , HgI ؊ 2 , HgBr ؊ 2 , and AuI ؊ 3 ) into the Lewis basic Bi 2 Sr 2 Ca n؊1 Cu n O 2n؉4؉ lattice. According to the X-ray di4raction and magnetic property measurements on these intercalates, it becomes clear that the basal increment upon intercalation (3.25+7.35 A s ) is governed by the interlayer geometry of the intercalant, while the accompanying T c change depends on the charge transfer between host and guest. The extended X-ray absorption 5ne structure and Raman studies reveal that mercuric halides are intercalated as linear molecules as in vapor state, while silver iodide forms a two-dimensionally extended ionicconducting channel. In the case of new gold iodide intercalate, unique trigonal planar AuI 3 species is identi5ed as the 5rst example of an isolated gold iodide molecule.