Study of the Effect of Cu2+ in the Lattice Dynamics of Doped Magnetites Obtained by the Hydrothermal Synthesis Method
Spectral Analysis Review
In this work, the effect of Cu 2+ on the structural and magnetic properties of samples of magnetite is addressed. Samples of magnetite, both pure and Cu 2+ doped, Fe 3-x Cu x O 4 , with x = 0, 5, 10 and 20 atm.% were synthesized hydrothermally. The two-lattice method was employed to measure the Mössbauer recoilless fraction of magnetite relative to hematite (f mag /f hem ) of the samples, looking for evidence of substitution of Fe 2+ by Cu 2+ . The relative recoilless fraction measurements were
... n measurements were performed by taking room temperature Mössbauer spectra of mixtures of each sample with analytical grade hematite. The Mössbauer measurements were complemented with Atomic Absorption Spectroscopy (AAS) and Energy Dispersive X-ray Spectroscopy (EDS). The analyses by AAS and EDS showed that the copper concentration in the final products increases with increasing the content of Cu 2+ in the starting solutions. The Mössbauer analyses showed a linear decrease trend of the relative Mössbauer recoilless fraction with increasing concentration of Cu 2+ in the samples, as well as a reduction in the hyperfine magnetic field, which was more significant in the octahedral sites than tetrahedral sites. The broadening of the Mössbauer spectral lines was more significant for the octahedral sub spectrum than for the tetrahedral sub spectrum. Our study points that Cu 2+ occupies preferentially the octahedral sites, where it substitutes Fe 2+ species, generating broadening in the lines of the octahedral sub spectrum and a reduction in the probability of having nuclear resonant absorption of Mössbauer gamma rays in the samples.