Influence of Metal Content on Size, Dispersion, and Magnetic Properties of Iron−Cobalt Alloy Nanoparticles Embedded in Silica Matrix

Abstract

Fe x Co 1-x ) y (SiO 2 ) 1-y nanocomposites were prepared by a sol-gel method, using tetraethoxysilane and metal acetates as precursors. Two sets of xerogel samples were prepared: in the first set x was kept equal to 0.5 and four y values were selected in the range 0.02-0.2; in the second set y was kept equal to 0.1 and three samples with x equal to 0.45, 0.50, and 0.70 were prepared. The samples were characterized by X-ray diffraction, TEM, and HREM to verify the formation of the FeCo alloy nanocrystals and to investigate their structure, morphology, and composition. All samples contain spherical FeCo alloy nanoparticles uniformly dispersed in the silica matrix with average size increasing with metal content. Magnetic measurements carried out on selected samples show a superparamagnetic behavior, with blocking temperature which depends on metal load, as a consequence of particle distance variation.

POSS containing organometallic polymers: synthesis, characterization and solid-state pyrolysis behavior

“…5a and b). 13 However, the same tendency was not so obvious in P2-Co-S ( Fig. 5c and d), possibly due to its good sinter-resistant properties.…”

One-step electroless deposition of Pd/Pt bimetallic microstructures by galvanic replacement on copper substrate and investigation of its performance for the hydrogen evolution reaction

“…Recently, it has been proved that this simple and spontaneous process is an attractive approach for the growth of structures directly on metal or semiconductor substrates such as deposition of Au on Si [2], Ag/Pd on Si [3], Cu on Si [4], Pt on Ti [5], Au on Ge [6], Pt on Ge [7], Cu on TaN [8], Cu on Al [9], Zn on Al [10], Ni on Al [11], Pd on Ag [12], Pt/Au on Cu [13], Au on Cu [14], Ag on Cu [15] and Au on Ag [16] and other combinations.…”

“…Bimetallic particles have great significance because of the modification of properties observed, compared with monometallics, not only due to size effects, but also as a result of the combination of different metals [12,17]. Among the various bimetallic particles, Pd/Pt particles are significant systems, and they play an important role as effective catalysts [18,19] in different electrochemical processes such as ORR [20,21] HER [22] and HOR [23].…”

Chemical Synthesis of Sub‐micrometer‐ to Nanometer‐Sized Magnetic FeCo Dice

“…[1][2][3][4][5] Although a large number of reports have appeared in the recent past, most of the chemical synthesis techniques reported until now employ environmentally unfriendly chemicals and tedious synthesis processes that extend over a couple of days. [3,6] Especially in the case of FeCo, most of the techniques require high temperatures during synthesis as well as post-annealing treatments, and the potential to control the composition and purity [7,8] is not discussed in detail.…”