Assessment of structure and critical temperature correlation in HgBa2CuO4 + δand Ca–La–Ba–Cu–O superconductors
✍ Scribed by D. Mogilyanski; E. Gartstein
- Publisher
- Elsevier Science
- Year
- 1997
- Tongue
- English
- Weight
- 215 KB
- Volume
- 21
- Category
- Article
- ISSN
- 0749-6036
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✦ Synopsis
HgBa 2 CuO 4+δ and (Ca x La 1-x )(Ba 1.75-x La 0.25+x )Cu 3 O 7±δ superconducting systems were structurally investigated employing Rietveld analysis. The doping of holes in Hg compounds was done by oxygenation and reduction methods. In Ca-La-Ba-Cu-O system the doping of holes was introduced via cation cosubstitution of Ca +2 for La +3 and La +3 for Ba +2 , so that the nominal charge of non-copper cations remained constant (= 7.25). The electronic structure was assessed by calculating Madelung site potentials. It was found that the difference V A of Madelung potentials on the apical and planar oxygen sites correlates with T c similar to the trends reported in the literature. Based on V A analysis it was possible to separate the intrinsic 'chemical pressure' effect on T c from the one caused by electron density redistribution in Ca-La-Ba-Cu-O system upon cosubstitution.