EXAFS analysis of grain boundaries in nanocrystalline Fe85Zr7B6Cu2\mathrm{Fe_{85}Zr_7B_6Cu_2} alloys

Nanocrystalline Fe85Zr7B6Cu2 alloys were obtained from the formerly amorphous Fe85Zr7B6Cu2 alloy by a heat treatment at several temperatures ranging from 480°C to 600°C. The ultrafine nanocrystalline structure of bcc-Fe grains with a grain size of 3–15 nm diameter embedded in an amorphous matrix was established using transmission electron microscopy. X-ray absorption spectra at the Fe K-edge for Fe85Zr7B6Cu2 amorphous and nanocrystalline alloys and metallic Fe foil were measured using synchrotron radiation.Fourier analysis of extended X-ray absorption fine structure (EXAFS) for alloys was performed and two models of grain boundaries in nanocrystalline Fe85Zr7B6Cu2 alloys were proposed. The heat treatment of alloys at temperatures of 480°C and 500°C creates simple boundaries between crystalline grains and amorphous matrix, while the heat treatment at higher temperatures from 540°C to 600°C can produce boundaries in the form of Fe-free interfaces with thickness of about 0.3 nm. A model of an Fe-free interface being a barrier for grain growth can explain the nanocrystallization phenomenon of Fe85Zr7B6Cu2 alloys

X-Ray Absorption Studies of Fe73.5\text{}_{73.5}Cu1\text{}_{1}Nb3\text{}_{3}Si15.5\text{}_{15.5}B7\text{}_{7} Amorphous and Nanocrystalline Alloys

The nanocrystalline state of the formally amorphous alloy Fe$\text{}_{73.5}$Cu$\text{}_{1}$Nb$\text{}_{3}$Si$\text{}_{15.5}$B$\text{}_{7}$ is achieved by a heat treatment at temperatures between 500°C and 600°C. The XANES and EXAFS methods were applied for investigation of local structure and chemical bonding around Fe atoms in amorphous and nanocrystalline alloys. The Fe K absorption spectra were measured in the transmission mode at room temperature for Fe$\text{}_{73.5}$Cu$\text{}_{1}$Nb$\text{}_{3}$Si$\text{}_{15.5}$B$\text{}_{7}$ amorphous and nanocrystalline alloys and compared with the spectra for Fe metallic foil and Fe$\text{}_{3}$Si polycrystalline samples

XAFS Study of Fe Intercalated Fullerite

Fe K edge XANES and EXAFS studies were performed to reveal the local structure around Fe ions in C60Fe2 fullerites. The measurements were carried out in transmission mode at LN2 temperature for the monoclinic and fcc C60Fe2 fullerite powder samples and other materials : ferrocene Fe(C5H5)2. Fe metal foil and α-Fe2O3. The XAFS spectra of the monoclinic C60Fe2 fullerite is almost identical to that of ferrocen. The XAFS spectra of the fcc C60Fe2 fullerite have shown that Fe neutral atoms, Fe2+ and Fe3+ ions appear in this fullerite due to annealing at temperature 850 K. The EXAFS study has proved the presence of small Fe clusters in this form of fullerite

C60\text{}_{60}FeC60\text{}_{60} Complexes in Fe Intercalated Fullerite Studied by X-Ray Absorption

The aim of Fe K edge XANES and EXAFS studies is to reveal the local structure around Fe ions in C$\text{}_{60}$Fe$\text{}_{x}$ intercalated fullerites. The measurements are performed in transmission mode at LN$\text{}_{2}$ temperature for C$\text{}_{60}$Fe$\text{}_{x}$ powder samples and other materials: ferrocene Fe(C$\text{}_{5}$H$\text{}_{5}$)$\text{}_{2}$, Fe metal foil and α-Fe$\text{}_{2}$O$\text{}_{3}$. The main result is that the XAFS spectra of the C$\text{}_{60}$Fe$\text{}_{2}$ intercalate is almost identical to that of ferrocene and very different from α-Fe and α-Fe$\text{}_{2}$O$\text{}_{3}$. The results support opinion that in the C$\text{}_{60}$Fe$\text{}_{x}$ intercalates the ferrocene-like bonds in complexes C$\text{}_{60}$FeC$\text{}_{60}$ are formed. Additionally, the XAFS spectra showed that neither remarkable amount of Fe metallic clusters nor oxidized iron particles are present in the C$\text{}_{60}$Fe$\text{}_{x}$ sample