Abstract
Erbium nickel-ferrite (NiErxFe2-xO4 where 0.00 <= x <= 0.05) nanofibers were prepared by a sol-gel electrospinning process utilizing polyvinylpyrrolidone (PVP) polymer (MW: 40.000). Nanofibers of as-electrospun nickel-ferrite with erbium substitution were calcinated in air at 700 degrees C for 6 h. After calcination, microscopy analysis indicated uneven nanofiber surfaces that were formed from grains. An increase in erbium concentration in the structure yielded an increase in the lattice parameters and the cell volume, but a decrease in the crystallite size. Elemental erbium, nickel, iron, and oxygen were present in the electrospun NiErxFe2-xO4 nanofibers with no impurities. The magnetic properties were examined via magnetization against magnetic field (M-H) measurements. The M-H curves of all prepared NiErxFe2-xO4 nanofibers were measured at two different temperatures; room temperature (T = 300 K) and low temperature (T = 10 K) throughout H of +/- 70 kOe. The values of M-s (saturation magnetization), M-r (remanence), H-c (coercivity), SQR = M-r/M-s (squareness ratio), and n(B) (magnetic moments) were determined. The prepared set of nanofibers showed soft ferrimagnetic behavior at both 300 and 10 K. At both measured temperatures M-s improved with increasing Er3+ concentration up to x = 0.02, then it decreased with further increase in the Er3+ content.