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A wet-chemistry method to determine the Bi and Cu valencies in Bi-Sr-Ca-Cu-O (2212) high-temperature superconductors

Author   Schweizer, Th.; Muller, R.; Gauckler, L.J.
Year   1994
Type   Journal Article
Journal   Physica C
Volume   225
Issue   1-2
Pages   143-148
Date   1994/5/10
Custom 1   JA
Custom 2   SUPRA
Abstract   A spectrometric method is presented to determine the average valency of Bi in Bi2Sr2CaCu2O8+[delta] high-temperature superconductors (HTSC's) to better than +/-0.005. Isostatically pressed samples of varying oxygen content were prepared by sintering in Ar-O2 atmospheres of oxygen partial pressures between 10-5 and 1 bar and temperatures between 300 and 900 [deg]C. Bi and Cu valencies were determined by a combination of iodometric titration and the spectrometric method permanganometry. This method takes into account the decay with time of the permanganate concentration in acidic aqueous solution. The latter is determined by light-absorption measurement at [lambda] = 526 nm. In the selected sintering regime the Bi valency varies between 3.09 and 3.15, the Cu valency between 2.06 and 2.11. Both Bi and Cu valencies increase linearly with increasing oxygen content [delta]. [Author abstract; 7 Refs; In English]
URL  
Record Number   172
Group   nonmet

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