ISSN:
1600-5724
Source:
Crystallography Journals Online : IUCR Backfile Archive 1948-2001
Topics:
Chemistry and Pharmacology
,
Geosciences
,
Physics
Notes:
The structural regularities of (M2Cu2O3)m(CuO2)n-type (M = Ca, Sr, Y, Bi) cuprates with ladder-type planes have been considered. On the basis of the structural studies of the samples grown by floating-zone and flux methods, it was concluded that the phase (M2Cu2O3)(Cu1+δO2+γ), described as the m/n = 1/1 member, with Cu-deficient Cu—O ribbons in the series (M2Cu2O3)m(CuO2)n can be treated as an individual structural type intermediate between SrCu2O3 and incommensurate-type phases (M2Cu2O3)m(CuO2)n with m ≠ n. The deficiency of the Cu sites in CuO ribbons is a particular crystal-chemistry feature of this structural type, in addition to the geometrical feature (m = n). The structural type of the `Cu-deficient ladder' can transform into the incommensurate-type phases (M2Cu2O3)m(CuO2)n (m/n = 5/7, 7/10, 9/13 etc.) in the presence of free [CuO4]6− radicals in the melt. A realization of the (M2Cu2O3)m(CuO2)n phase with a particular m/n value is caused by the type of M cation. On the basis of recent data, the role of trivalent ions in the chemical composition of the (M2Cu2O3)m(CuO2)n-type compounds was also analyzed. The occurrence of the superconductivity in (Sr, Ca)CuO2 samples is discussed by analogy with cuprates of the infinite-layer structure.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1107/S0108767399014889
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