In (Nd0.33 Eu0.38 Gd0.28) Ba2 a new type of nanometer-scale pinning center was created by choosing an appropriate matrix chemical ratio. Such a pinning center could be controlled via externally added small quantity of 211 (NEG-211 or Gd-211) secondary phase. Microstructure analysis combined with magnetic characterization clarified that the sample with a high irreversibillty field always exhibits chemical modulation and formation of a special nanometer-scale lamellar structure. High magnification STM observations revealed that the nano-Iamellas consist of rows of aligned NEG-rich clusters 3 to 4 nm in size. This new material with the Nd:Eu:Gd ratio of 1:1.25:0.85 combined with 5 mol% 211 secondary phase exhibits the high secondary peak position at around 4.5 T and the irreversibility field over 14 T at 77 K for Ha ∥ c-axis.
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