The Ni-rich nanostructured solid solutions of Ni1−xMx (M = Cd, Co and Cu)

Abstract

The nanostructured solid solutions (NSSes) of Ni–Cd (Cu, Co) with the FCC lattice were obtained by a simple chemical method. The NSSes consist of nanocrystallites (10–25 nm) which form the primary aggregates (40–80 nm) composing the secondary aggregates (100–500 nm). The Ni–Cd and Ni–Cu nanocrystallites were shown to be anisometric, which is unusual for the FCC lattice. The Ni–Cd aggregates contain the structural units consisted of the stratification of the nano-thick crystallites by the (111) and (200) faces with a wide surface in common and spatial orientation. The spatial heterogeneity of compounds for the aggregates of Ni–Cd and Ni–Cu can be explained because of the differences in the nanocrystal chemical compositions. The main reason of it is in the differences in the redox potentials of the components of the bimetallic NSSes obtained by chemical reactions. The surface of the primary aggregates contains H2O, O2, CO2 and, probably, hydroxide and oxide as nano-islets in a layer whose thickness is approximately 1–3 nm. These inclusions can be desorbed or decomposed at 100 °С–140 °С, 120 °С–220 °С and 300 °С–400 °С accordingly. The obtained non-equilibrium solid solutions (up to 5% of Cd or Cu) have saturation magnetization in low magnetic fields also decrease in this magnetization and coercivity (80–260 Oe at 300 K).