Self-Organized Growth of Clustered Structures in La0.6–xNdxSr0.3Mn1.1O3–δ Doped Perovskites

Resumo

Our results on the atomic order in La_0.6–xNd_xSr_0.3Mn_1.1O_3–δ manganites with partial Nd substitution for La (x = 0–0.4) demonstrate that all of the materials consist of differently sized groups: microcrystalline groups with long-range atomic order, D = 300–600 Å in size; clustered groups with mesoscopic atomic order and D = 100–200 Å; amorphous clustered groups with D = 20–30 Å; and a disordered material with short-range atomic order, on a length scale of two or three interatomic distances (D ~ 10 Å). It has been shown that, in the case of partial Nd substitution for La (x = 0.1–0.2) in the manganite, clusters 100–200 Å in size, as well as those of the rhombohedral phase 20–50 Å in size, initiate an FM → AFM magnetic phase transition in the range 200–250 K. Neodymium substitution for half of the lanthanum (in La_0.3Nd_0.3Sr_0.3Mn_1.1O_3–δ) has been found to result in the development of self-organization processes, with a reduction in cluster size fluctuations in the range ΔD ≈ ±50 Å in the orthorhombic ferromagnetic and rhombohedral antiferromagnetic phases.