TY - JOUR
T1 - Shearing mechanism in the Bi-Sr-Cu oxycarbonates
T2 - HREM study of a new collapsed phase Bi15Sr29Cu12(CO3)7O 56
AU - Hervieu, Maryvonne
AU - Caldés, Maria T.
AU - Pelloquin, Denis
AU - Michel, Claude
AU - Cabrera, Saul
AU - Raveau, Bernard
PY - 1996/2
Y1 - 1996/2
N2 - A new oxycarbonate, Bi15Sr29Cu12(CO3)7O 56, has been synthesized. It crystallizes in a monoclinic cell, a = 22.139(7) Å, b = 5.498(2) Å, c = 39.82(1) Å and β = 119.45(2)°, with the possible space groups A2/m, Am or A2. Its structure, determined by an HREM investigation, is derived from that of the single intergrowth (Bi2Sr2CuO6) [Sr2Cu(CO3)O2] by a shearing mechanism along the (010) plane, so that it can be described as an assembly of [2201]1[S2CC]1 ribbons which are m = 7 CuO6 octahedra wide and shifted by 12 Å with respect to each other. In fact, local substitutions exist such that the phase cannot be classified as a true shear structure, and for this reason it is referred to as 'collapsed'. The detailed microstructural study allows other collapsed members (m = 8) oriented domains with chemical twins to be identified. New extended defects corresponding to the intergrowth of 2201-type ribbons in the oxycarbonate matrix along [001] and [201], are also observed. The correlation between the shearing mechanism in this structure and the amplitude of the modulation in the single intergrowth [2201]1[S2CC]1 compounds is discussed.
AB - A new oxycarbonate, Bi15Sr29Cu12(CO3)7O 56, has been synthesized. It crystallizes in a monoclinic cell, a = 22.139(7) Å, b = 5.498(2) Å, c = 39.82(1) Å and β = 119.45(2)°, with the possible space groups A2/m, Am or A2. Its structure, determined by an HREM investigation, is derived from that of the single intergrowth (Bi2Sr2CuO6) [Sr2Cu(CO3)O2] by a shearing mechanism along the (010) plane, so that it can be described as an assembly of [2201]1[S2CC]1 ribbons which are m = 7 CuO6 octahedra wide and shifted by 12 Å with respect to each other. In fact, local substitutions exist such that the phase cannot be classified as a true shear structure, and for this reason it is referred to as 'collapsed'. The detailed microstructural study allows other collapsed members (m = 8) oriented domains with chemical twins to be identified. New extended defects corresponding to the intergrowth of 2201-type ribbons in the oxycarbonate matrix along [001] and [201], are also observed. The correlation between the shearing mechanism in this structure and the amplitude of the modulation in the single intergrowth [2201]1[S2CC]1 compounds is discussed.
UR - http://www.scopus.com/inward/record.url?scp=0006816923&partnerID=8YFLogxK
U2 - 10.1039/JM9960600175
DO - 10.1039/JM9960600175
M3 - Artículo
AN - SCOPUS:0006816923
VL - 6
SP - 175
EP - 181
JO - Journal of Materials Chemistry
JF - Journal of Materials Chemistry
SN - 0959-9428
IS - 2
ER -