Structure and applied-field Mossbauer studies of NiCuZn ferrite

Ni0.6Cu0.2Zn0.2Fe2O4 powder was synthesized by the solid-state reaction method. The crystal structure was found to be a cubic spinel with the lattice constant alpha(0) of 8.373 angstrom and internal structure parameter (x) of the oxygen was 0.254. Ni and Cu ions in NiCuZn ferrite prefer octahedral sites B and Zn ions prefer tetrahedral sites A. Based on the distribution probability, we have analyzed Mossbauer spectra measured at 4.2 K as 5 sets with six-lines. Hyperfine fields of A and B sites at 4.2 K in zero magnetic field were H-hf(B-0) = 547 kOe, H-hf(B-1) = 532 kOe, H-hf(B-2) = 519 kOe, H-hf(B-3) = 491 kOe, and H-hf(A) = 507 kOe. Applied-field Mossbauer spectra of the Ni0.6Cu0.2Zn0.2Fe2O4 were measured with external field under 50 kOe, parallel to the incident gamma-ray at 4.2 K. The hyperfine field H-hf(A) of A sites under 50 kOe was 521 kOe, larger than that under no applied-field. At B site the average value of hyperfine field < Hhf(B)> was 447 kOe, smaller than < H-hf(B)> = 522 kOe under no applied-field. Also, we noticed that the second and fifth absorption lines of Mossbauer spectra completely disappeared above 10 kOe, indicating that the spins of Fe ions at A and B sites were collinear to the applied-field. The Fe valence state was determined to be ferric from the isomer shift values. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3549556]