INVESTIGADORES
ULLA Maria Alicia Del H.
artículos
Título:
of Lanthanum deficient compositions in the systems La-Cu-O and La-Sr-Cu-O
Autor/es:
S. ALCONCHEL; M. A, ULLA; E. A. LOMBARDO
Revista:
Journal of Material Science
Editorial:
Kluw er Academic Publishers
Referencias:
Lugar: Amsterdam; Año: 1995 vol. 30 p. 2227 - 2234
ISSN:
0022-2461
Resumen:
The effect of varying lanthanum composition upon the formation of the nonsuperconducting La1.67Sr0.33Cu2O5-δ and the stoichiometry variation tolerance of the ternary system La2-xSrxCuO4 (with x=0 and 0.15) were investigated using a variety of techniques. Results indicate that total conversion to La2CuO4 from freeze-dried precursors with an La:Cu = 2.00:1 ratio is achieved after sintering (1253 K, 12 h) and annealing in oxygen (773 K, 6 h). Small variations in the stoichiometry of solids La2-xSrxCuO4 with x=0 and 0.15 were detected. Lanthanum-deficient composition in the ternary system induces the formation of the non-superconducting phase whose stoichiometry is better represented by La1.60Sr0.40Cu2O5-δ. The temperature-programmed reduction profiles of the cuprates can be associated with the formation of more or less stable intermediates.
