Perovskite-type oxides. 1: Structural, magnetic, and morphological properties of LaMn{sub 1{minus}x}Cu{sub x}O{sub 3} and LaCo{sub 1{minus}x}Cu{sub x}O{sub 3} solid solutions with large surface area
- Univ. La Sapienza, Rome (Italy). Dept. di Chimica
- CNR, Naples (Italy). Ist. di Ricerche Sulla Combustione
- Univ. Federico II, Naples (Italy). Dept. di Ingegneria Chimica
Perovskite-type compounds of general formula LaMn{sub 1{minus}x}Cu{sub x}O{sub 3} and LaCo{sub 1{minus}x}Cu{sub x}O{sub 3} (x = 0.0, 0.2, 0.4, 0.6, 0.8, 1.0) were prepared by calcining the citrate gel precursors at 823, 923, and 1073 K. The decomposition of the precursors was followed by thermal analysis and the oxides were investigated by means of elemental analysis (atomic absorption and redox titration), X-ray powder diffraction, BET surface area, X-ray absorption (EXAFS and XANES), electron microscopy (SEM and TEM), and magnetic susceptibility. LaMn{sub 1{minus}x}Cu{sub x}O{sub 3} samples are perovskite-like single phases up to x = 0.6. At x = 0.8 CuO and La{sub 2}CuO{sub 4} phases are present in addition to perovskite. Magnetic susceptibility studies show a ferromagnetic behavior that decreases with increase in x. Materials with not very clear morphology and crystals with definite structure are distinguishable by SEM for samples calcined at 1073 and at 1273 K, respectively. TEM patterns, for samples calcined at 1073 K, evidence almost regular hexagonal prismatic crystals connected to form linked structures and some spotty crystals, suggesting short-range ordered local defects. For copper-containing samples, calcined at 1273 K, a higher degree of defectivity (probably associated with the interaction of anion vacancies) and the occurrence of planar faults are shown by TEM.
- OSTI ID:
- 696664
- Journal Information:
- Journal of Solid State Chemistry, Vol. 146, Issue 2; Other Information: PBD: Sep 1999
- Country of Publication:
- United States
- Language:
- English
Similar Records
Magnetic ordering in (Y sub 1 minus x Pr sub x )Ba sub 2 Cu sub 3 O sub 7 as evidenced by muon spin relaxation
Defect structure and superconducting properties of La[sub 1. 8]Sr[sub [ital x]]Ca[sub 1. 2[minus][ital x]]Cu[sub 2]O[sub 6[minus][delta]]