The far-infrared spectra of some mixed cobalt zinc and magnesium zinc ferrites

Abstract

The far-infrared spectra of five mixed ferrites in the range 200 t o 640 cm-I are reported. Four bands are observed. The high frequency band (vl) and low frequency band (v2) are assigned to the tetrahedral and octahedral complexes, respectively. A small band (v3) around v2 is observed and its intensity increases with divalent octahedral metal ion concentration. This band is assigned to the octahedral divalent metal-oxygen ion complexes. The lowest band observed for the highest concentration of cobalt is attributed to the lattice vibrations of the system. Die Ferninfrarot-Spektren von funf Mischferriten im Bereich 200 bis 640 cm-l werden mitgeteilt. Vier Banden werden beobachtet. Die hochfrequente Bande (vl) und die niederfrequente Bande (vy) werden den'tetraedrischen bzw. oktaedrischen Komplexen zugeordnet. Eine schwache Bande (v,) bei v, wird beobachtet, deren Intensitat mit der Konzentration divalenter oktaedrischer Metallionen zunimmt. Diese Bande wird den oktaedrischen divalenten Metall-Sauerstoff-Komplexen zugeordnet. Die niedrigste Bande, die fur die hochste Kobaltkonzentration beobachtet wird, wird den Gitterschwingungen des Systems zugeschrieben.

Structural, magnetic and electrical properties of the lithium ferrite obtained by ball milling and heat treatment

“…ions in the above-mentioned samples (Mazen et al 1997). The fourth vibrational band t 4 (around 265 cm -1 ) is due to the lattice vibration (Josylu and Sobhanadri 1981). It has been shown by Potakova et al (1972) that the presence of Fe 2?…”

On the Role of Morphology of CoFeO4 Spinel in Methanol Anaerobic Oxidation

“…Besides the Fe 3+ ions in octahedral sites, Co 2+ ions are also present in octahedral sites. As anticipated above, the higher-ν component (termed S (Oh) ) can be ascribed to the surface fraction of both (Fe-O) Oh and (Co-O) Oh modes, whereas the other two signals located at ~370 cm -1 and ~310 cm -1 (termed B Fe (Oh) and B Co (Oh) ) are ascribable to (Fe-O) Oh and (Co-O) Oh bulk vibrations, respectively [60]. Also in this case, the S (Oh) /B (Oh) integrated intensity ratio (where B (Oh) comprehends both B Fe (Oh) and B Co (Oh) ) depends on the calcination temperature: it decreases from 0.28 for CF450 to 0.09 for CF750, confirming the above speculations about the surface/bulk nature of the various components.…”

Cationic Distribution and Oxidation Mechanism of Trivalent Manganese Ions in Submicrometer MnxCoFe2−xO4Spinel Ferrites

“…2 (14). It has been reported previously that for inverse II-III spinels such as CoFe 2 O 4 the high-frequency band 1 belongs to the tetrahedral sites and the low-frequency band 2 to the octahedral complexes (15,16). It appears that the these bands 1 and 2 .…”