Search

57Fe ion implanted chromium foils have been analyzed by conversion electron Mössbauer spectroscopy. After annealing at temperatures up to 600 °C, the CEM spectra show two magnetic components which are attributed to iron atoms in the core and the outer layer of grains. By means of a simple model using the spectral data, the final average iron grain has been evaluated to be about 5 nm.

An Fe/Ni multilayer of overall FeNi3 composition, prepared by Joule effect deposition, has been irradiated with 200 keV krypton ions at a nominal dose of 5×1015ions/cm2 to induce mixing at the interface. Depth profiling AES, RBS, XRD (glancing angle) and CEMS have been used to characterize the samples before and after irradiation and also after subsequent mild annealing. In the final structure, we have recognized the presence of embryos of an ordered FeNi3 superlattice.

Using conversion electron Mössbauer spectroscopy, we have studied the hyperfine field distributions of ultra-thin iron films interfaced on both sides with nickel. The configuration of the studied system was (Ni/57Fe/Ni)n=(20 nm/X nm/20 nm)n, withn=3–7 andX=0.5–1.5 nm. The films were grown at room temperature in high vacuum on (111) buffer layers of nickel previously deposited on mica substrates at 300 °C. It has been found that the average hyperfine field is practically independent of the iron layer thickness, while this parameter strongly affects the distribution profiles and the orientation of iron atom spins.

Abstract: Fe2O3−TiO2 powders were obtained by the sol-gel method through hydrolysis and polycondensation of titanium n-butoxide and different iron compounds in alcoholic solutions. As iron oxide precursors, Fe(III)ethoxide, Fe(III)acetylacetonate and Fe(NO3)39H2O were employed. The gels were dried and heat treated in air and in nitrogen atmosphere at different temperatures. It was demonstrated by means of Mssbauer spectroscopy that the use of different iron precursors can slightly affect the oxidation state of iron and the nature of the crystalline phases developed only when the heat treatment is performed in a non-oxidizing atmosphere. The results are discussed also in connection with previous X-ray diffraction data.

Abstract: Conversion electron Mssbauer spectroscopy (CEMS) has been used to investigate the various Fe coordination states at the interface of the Fe/SiO2 couple after irradiation with 200 keV Kr ions in the dose range from 2.51015 to 3.51016 ions/cm2. After removal of the unmixed Fe layer by a simple etching procedure, it was possible to recognize the presence of small Fe clusters, Fe-oxide and Fe-silicate phases, whose relative amount has been determined as a function of the irradiation dose. The amount of mixed Fe has been evaluated in the etched samples by means of Rutherford backscattering spectrometry (RBS). Structural changes in the interfacial region after thermal annealings for 5 h at 500 and 700C have been detected and correlated to corre-sponding changes in optical properties.

Conversion electron Mössbauer spectroscopy (CEMS) has been used to study tin oxide films prepared by sol-gel dipping and sputtering. The spectra of films prepared by sol-gel route result close to that of crystalline SnO2after heat treatment at a temperature as low as 150°C. The Mössbauer parameters of as sputter deposited films indicate that the structure of the deposited stannic oxide has an amorphous character more pronounced for thinner samples. The structure becomes predominantly that of crystalline SnO2by heating at 550°C for 30 min provided the film thickness is higher than 10 nm.