The transition-metal spinel MgTi2O4 undergoes a metal-insulator (M-I) transition on cooling below T(M-I)=260 K. A sharp reduction of the magnetic susceptibility below T(M-I) suggests the onset of a magnetic singlet state. Using high-resolution synchrotron and neutron powder diffraction, we have solved the low-temperature crystal structure of MgTi2O4, which is found to contain dimers with short ...

The Mössbauer spectra of nanoferrite materials such as Ni0.25Mn0.75Fe2O4, Co0.5Mn0.5Fe2O4 and Ni0.4Co0.6Fe2O4 have been reported and the above materials were prepared by sol-gel combustion method using metal nitrates as source material and Polyvinyl alcohol(PVA) as...

Using an alternating reactive ion &am sputtering technique, Co ion was doped in epitaxially growing Bi3Fe5Ol, garnet film. The intense enhancement of magnetization, coercivity, and optical absorption at 633nm was observed. The Faraday hysteresis loop for slightly Cwdoped film showed anomalous behavior. Those phenomena can be understood considering the composite film structure in which fine part...

To study magnetic states in ferrimagnetic Fe-oxides, we have measured magnetic circular x-ray dichroism at K-edge of Id-transition metal. The observed dichroic signals are separately assigned to the contribution come from 3d-cation in tetrahedral or octahedral sites. We discuss the magnetic states of 3d-metal ion in terms of local enviroment. Magnetic circular x-ray dichroism (MCXD is a powerfu...

From an interplay of atom-resolved noncontact atomic force microscopy, surface x-ray diffraction experiments, and density functional theory calculations, we reveal the detailed atomic-scale structure of the (100) surface of an insulating ternary metal oxide, MgAl2O4 (spinel). We surprisingly find that the MgAl2O4(100) surface is terminated by an Al and O-rich structure with a thermodynamically ...

Natural peridotite samples containing olivine, orthopyroxene, and spinel can be used to assess the oxygen fugacity ( fO2) of the upper mantle. The calculation requires accurate and precise quantification of spinel Fe3+/SFe ratios. Wood and Virgo (1989) presented a correction procedure for electron microprobe (EPMA) measurements of spinel Fe3+/SFe ratios that relies on a reported correlation bet...

Raman spectra of a single-crystal fragment of hydrous c-Mg2SiO4, synthesized in a multianvil press, have been measured in a diamond-anvil cell with helium as pressure-transmitting medium to 56.5 GPa at room temperature. All five characteristic spinel Raman modes shift continuously up to the highest pressure, showing no evidence for a major change in the crystal structure despite compression wel...

Manganese oxides of spinel structure, LiMn2O4, Li1-xNixMn2O4 (0.25 ≤ x≤ 0.75), and NiMn2O4, were studied by EDS, XRD, SEM, magnetic (M-H, M-T), and XPS measurements. The samples were synthesized by an ultrasoundassisted sol-gel method. EDS analysis showed good agreement with the formulations of the oxides. XRD and Rietveld refinement of X-ray data indicate that all samples crystallize in the Fd...

A spinel LiMn1.5Ni0.5O4 (LMNO) cathode material synthesized by a sol-gel method is modified by MgF2 nano-coating via a wet coating strategy. The results of X-ray diffraction (XRD), Raman spectroscopy, field emission scanning electron microscopy (FESEM) and high resolution transmission electron microscopy (HRTEM) showed that the MgF2 nano-coating layers do not physically change the bulk structur...