Investigation of Ga substitution in cobalt ferrite (CoGaxFe2-xO4) using Mossbauer spectroscopy

TitleInvestigation of Ga substitution in cobalt ferrite (CoGaxFe2-xO4) using Mossbauer spectroscopy
Publication TypeJournal Article
Year of Publication2008
AuthorsKrieble K, Devlin M, Lee SJ, Aldini ST, Snyder JE
Journal TitleJournal of Applied Physics
Date PublishedApr
Type of ArticleProceedings Paper
ISBN Number0021-8979
Accession NumberISI:000255043200586

Ga-substituted cobalt ferrite oxides show promise as high magnetostriction, high sensitivity magnetoelastic materials for sensor and actuator applications, but their atomic-level behavior is not yet well understood. In this study, the magnetic environments of the Fe atoms in Ga-substituted cobalt ferrite have been investigated using Mossbauer spectroscopy. A series of five powder samples with CoGaxFe2-xO4 compositions (x=0.0-0.8) was investigated using transmission geometry. Results show two distinct six-line hyperfine patterns, which are identified as Fe in A (tetrahedral) and B (octahedral) spinel sites. Increasing Ga concentration is seen to decrease the hyperfine field strength for both A and B sites, as well as increasing the width of those distributions, consistent with the nonmagnetic nature of Ga3+ ions. Effects are more pronounced for the B sites than the A sites. Results for Ga substitution show more pronounced effects than for previous studies with Cr3+ or Mn3+ substitution: the hyperfine fields decrease and distribution widths increase at greater rates, and the differences between A and B site behavior are more pronounced. Results indicate that at least for the lower Ga concentrations, the Ga3+ ions substitute predominantly into the A sites, in contrast to Cr3+ and Mn3+ which substitute into the B sites. This interpretation is supported by measurements of magnetization at low temperatures. (C) 2008 American Institute of Physics.

Alternate JournalJ. Appl. Phys.