Microstructural and Mössbauer properties of low temperature synthesized Ni-Cd-Al ferrite nanoparticles

We report the influence of Al3+ doping on the microstructural and Mössbauer properties of ferrite nanoparticles of basic composition Ni0.2Cd0.3Fe2.5 - xAlxO4 (0.0 ≤ x ≤ 0.5) prepared through simple sol-gel method. X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray, transmission electron microscopy (TEM), Fourier transformation infrared (FTIR), and Mössbauer spectroscopy techniques were used to investigate the structural, chemical, and Mössbauer properties of the grown nanoparticles. XRD results confirm that all the samples are single-phase cubic spinel in structure excluding the presence of any secondary phase corresponding to any structure. SEM micrographs show the synthesized nanoparticles are agglomerated but spherical in shape. The average crystallite size of the grown nanoparticles was calculated through Scherrer formula and confirmed by TEM and was found between 2 and 8 nm (± 1). FTIR results show the presence of two vibrational bands corresponding to tetrahedral and octahedral sites. Mössbauer spectroscopy shows that all the samples exhibit superparamagnetism, and the quadrupole interaction increases with the substitution of Al3+ ions

AC magnetic properties of the soft magnetic composite based on nanocrystalline ni-fe powders obtained by mechanical alloying

International audienc

AC magnetic properties of the soft magnetic composite based on nanocrystalline ni-fe powders obtained by mechanical alloying

International audienc

AC magnetic properties of the soft magnetic composites based on Supermalloy nanocrystalline powder prepared by mechanical alloyin

International audienc

Magnetic properties of nanocrystalline Ni3Fe compacts prepared by spark plasma sintering

International audienceNanocrystalline Ni3Fe compacts were successfully prepared by spark plasma sintering starting from wet mechanically alloyed powders. The influences of the sintering conditions: sintering temperature, sintering time and particle size on the compact magnetic properties are investigated. It is found that high sintering temperature, increased sintering duration and larger particle size leads to compacts with improved soft magnetic properties. A contamination with carbon of the compacts during the sintering processes has been found to reduce their magnetic properties. It is found that a heat treatment at the temperature of 450 degrees C during 4 h, in hydrogen atmosphere, leads to an improvement of the compact coercivity and of the maximum relative permeability of the compact to up to 600% and 50% respectively. Spark plasma sintering can consequently be considered as promising compaction technique for processing Ni3Fe nanocrystalline powder in particular and nanocrystalline soft magnetic alloys in general

Structural and magnetic behaviour of SmCo4/alpha-Fe nanocomposites obtained by mechanical milling and subsequent annealing

International audienceSmCo5+20%Fe magnetic nanocomposites have been obtained by mechanical milling in a planetary mill and subsequent annealing. The influence of the milling and annealing conditions on the magnetic and structural behaviour of SmCo5/alpha-Fe has been studied by X-ray diffraction, electron microscopy, magnetic measurements and Mossbauer spectrometry

A structural investigation of SmCo5/Fe nanostructured alloys obtained by high-energy ball milling and subsequent annealing

International audienceSmCo 5 /Fe nanostructured alloys with 20 wt% Fe, obtained by high energy ball milling of SmCo 5 and Fe powders, were investigated by 57 Fe Mössbauer spectrometry, X-ray diffraction and tomographic atom probe. The Mössbauer analysis reveals that during the first stages of milling, an interdiffusion of Co and Fe occurs, leading both to the formation of α-Fe(Co) regions in α-Fe and to the introduction of Fe in SmCo 5 regions. Annealing at temperatures up to 650°C for 0.5h promotes interdiffusion further leading to the formation of an unique α-Fe(Co) phase and a Fe-richer Sm(Co, Fe) 5 phase. The Co/Fe interdiffusion is confirmed by tomographic atom probe analysis. The data are discussed and compared to the results of previous magnetic measurements

A structural investigation of SmCo5/Fe nanostructured alloys obtained by high-energy ball milling and subsequent annealing

International audienceSmCo 5 /Fe nanostructured alloys with 20 wt% Fe, obtained by high energy ball milling of SmCo 5 and Fe powders, were investigated by 57 Fe Mössbauer spectrometry, X-ray diffraction and tomographic atom probe. The Mössbauer analysis reveals that during the first stages of milling, an interdiffusion of Co and Fe occurs, leading both to the formation of α-Fe(Co) regions in α-Fe and to the introduction of Fe in SmCo 5 regions. Annealing at temperatures up to 650°C for 0.5h promotes interdiffusion further leading to the formation of an unique α-Fe(Co) phase and a Fe-richer Sm(Co, Fe) 5 phase. The Co/Fe interdiffusion is confirmed by tomographic atom probe analysis. The data are discussed and compared to the results of previous magnetic measurements

Magnetic and thermomagnetic studies of the formation of the Rhometal powders by high energy mechanical milling

International audienceNanocrystalline Rhometal (36Ni64Fe, wt. %) powders have been obtained by mechanical alloying under argon atmosphere. The initial mixture was milled up to 20 h. In order to eliminate internal stresses and to improve the solid state reaction annealing at 350 °C was performed for 4h. The alloy formation is obtained after 8 h of milling. A mean crystallite size of 10 ± 4 nm is obtained after 20 hours of milling. The magnetization values for the as-milled samples are between that of the starting sample and that of the as cast one. The evolution of the magnetization versus the milling time is discussed. The thermomagnetic analysis shows the Curie temperatures confirming the alloy formation by milling. As a result of the solid state reaction by milling means, a continuous decrease of the magnetization with increasing the temperature is recorded, similarly to the behaviour of the classical cast alloy