Structural and Magnetic Properties of <inline-formula> <tex-math notation="TeX">\(\textbf {x}\) </tex-math></inline-formula>Fe<sub>2</sub> TiO<sub>4</sub><inline-formula> <tex-math notation="TeX">\(\cdot \) </tex-math></inline-formula> (<inline-formula> <tex-math notation="TeX">\(\textbf {1}\boldsymbol {-}\boldsymbol {x}\) </tex-math></inline-formula>)Fe<sub>3</sub>O<sub>4</sub> (<inline-formula> <tex-math notation="TeX">\(\textbf {0.75}\boldsymbol {\leq x \leq }1\) </tex-math></inline-formula>)

Abstract

Titanomagnetites (TMs) [pseudobinary (1 - x)Fe 3 O 4 · xFe 2 TiO 4 oxides, where, e.g., TM75 corresponds to x-0.75] are magnetic minerals with a spinel structure. Ulvospinel (Fe 2 TiO 4 ) and TMs were made using a solid-state synthesis technique, and transmission electron microscopy (TEM) characterization and measurement of the TM samples were performed to further confirm the homogeneity of the samples and cation site occupancies. The Mossbauer spectra in the TMs exhibited an anomalous composition dependence at x=0.95, when fitted with two instead of three quadrupole split doublets. This result was reinforced by the obtained dependence of the recoilless fraction on the composition, which exhibited an extremum at x=0.95.