Document Type

Article

Publication Date

4-1991

DOI

10.1063/1.348027

Publication Title

Journal of Applied Physics

Volume

69

Issue

8

Pages

5355–5357

Conference Name

35th Annual Conference on Magnetism and Magnetic Materials, San Diego, California (USA), 29 Oct−1 Nov 1990

Abstract

The magnetic and crystalline properties of a plasma‐sprayed coating of the microwave absorbing zinc‐nickel ferrite, (Zn0.41Ni0.59 )Fe2O4 have been studied at 300 K using the Mössbauer effect and x‐ray diffraction (XRD). Both techniques indicate that the plasma‐sprayed material separated into two phases. The first is a nickel‐rich phase with magnetic fields of 47.5 and 44.5 T at the tetrahedral and octahedral sites, respectively. The second is a zinc‐rich phase, zinc meta‐ferrite, having a small magnetic field of 4.2 T. The quadrupole splitting of this second phase is ΔE=0.34 mm s−1, which is the same as in pure nonmagnetic zinc ferrite. XRD analysis shows that the zinc‐rich phase remains cubic with a0= 8.389 Å and the zinc meta‐ferrite phase is tetragonal with the same lattice parameters as the cubic phase except for one elongated axis given by c0 =8.488 Å. This is much larger than the spacing for any of the series of zinc‐nickel ferrites. The isomer shift of the zinc meta‐ferrite is 0.710 mm s−1, which indicates that a large fraction of Fe3+ was reduced during the spraying process. Annealing the sprayed coating at temperatures less than 400 °C converted the zinc meta‐ferrite into a magnetic phase that now exhibits magnetic fields close to those in the nickel‐rich phase. However, the large isomer shift remains, indicating that the ferrous iron is still present. XRD shows that the phase is now cubic. Annealing up to 650 °C gradually oxidized all of the Fe2+ in the material and restored the magnetic and crystalline properties of the plasma‐sprayed coating to very close to those of the unsprayed ferrite.

Rights

"Under the terms of its License to Publish Agreement, AIP Publishing grants the Author(s) of papers submitted to or published in one of AIP Publishing journals or conference proceedings the following rights: The right to Deposit the VOR in a repository in compliance with university or funder requirements 12 months after publication by AIP Publishing."

© American Institute of Physics

Included with kind permission from the author(s).

Original Publication Citation

Dooling, T. A., & Cook, D. C. (1991). Phase changes in plasma‐sprayed zinc‐nickel ferrite. Journal of Applied Physics, 69(8), 5355-5357. https://doi.org/10.1063/1.348027

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