Effect of the Silica Cover on the Properties of Co3 O 4 Nanoparticles
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Cobalt oxide nanoparticles were functionalized with sodium citrate and coated with a silica shell (Co3O4%40Q%40SiO2). Different experimental configurations were tested in order to obtain low-sized cobalt oxide nanoparticles with high crystallinity, using the chemical reduction-oxidation method. Then, the nanoparticles were coated with silica using the Stöber method, obtaining a silica cover on top of the cobalt oxide nanoparticle surface with a few nanometers thickness. This method permits the functionalization of the nanoparticles at the time of coating. Results show that with a heat treatment of 500 ∘C, high-crystallinity cobalt oxide nanoparticles are obtained with a spherical shape and an average diameter of 30 nm, whereas the silica cover has 5 nm thickness. Evidence of nanoparticle functionalization was obtained through the measurement of the absorption bands of the functional groups of the sodium citrate with a silica cover. In addition, coated nanoparticles show a reduction of their magnetic remanence as well as their coercivity with respect to the uncoated nanoparticles since silica acts as barrier avoiding superficial contact between magnetic nanoparticles. © 2016, Springer Science Business Media New York.
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Cobalt oxide nanoparticles were functionalized with sodium citrate and coated with a silica shell (Co3O4%40Q%40SiO2). Different experimental configurations were tested in order to obtain low-sized cobalt oxide nanoparticles with high crystallinity, using the chemical reduction-oxidation method. Then, the nanoparticles were coated with silica using the Stöber method, obtaining a silica cover on top of the cobalt oxide nanoparticle surface with a few nanometers thickness. This method permits the functionalization of the nanoparticles at the time of coating. Results show that with a heat treatment of 500 ∘C, high-crystallinity cobalt oxide nanoparticles are obtained with a spherical shape and an average diameter of 30 nm, whereas the silica cover has 5 nm thickness. Evidence of nanoparticle functionalization was obtained through the measurement of the absorption bands of the functional groups of the sodium citrate with a silica cover. In addition, coated nanoparticles show a reduction of their magnetic remanence as well as their coercivity with respect to the uncoated nanoparticles since silica acts as barrier avoiding superficial contact between magnetic nanoparticles. © 2016, Springer Science%2bBusiness Media New York.
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Cobalt oxide nanoparticles were functionalized with sodium citrate and coated with a silica shell (Co3O4@Q@SiO2). Different experimental configurations were tested in order to obtain low-sized cobalt oxide nanoparticles with high crystallinity, using the chemical reduction-oxidation method. Then, the nanoparticles were coated with silica using the Stöber method, obtaining a silica cover on top of the cobalt oxide nanoparticle surface with a few nanometers thickness. This method permits the functionalization of the nanoparticles at the time of coating. Results show that with a heat treatment of 500 ∘C, high-crystallinity cobalt oxide nanoparticles are obtained with a spherical shape and an average diameter of 30 nm, whereas the silica cover has 5 nm thickness. Evidence of nanoparticle functionalization was obtained through the measurement of the absorption bands of the functional groups of the sodium citrate with a silica cover. In addition, coated nanoparticles show a reduction of their magnetic remanence as well as their coercivity with respect to the uncoated nanoparticles since silica acts as barrier avoiding superficial contact between magnetic nanoparticles. © 2016, Springer Science%2bBusiness Media New York.
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Cobalt oxide nanoparticles; Core-shell composites; Functionalized magnetic nanoparticles; Silica coating Coatings; Cobalt; Magnetism; Nanoparticles; Silica; Sodium; Chemical reduction; Coated nanoparticles; Cobalt oxide nanoparticles; Core-shell composites; Magnetic nano-particles; Magnetic remanence; Nanoparticle functionalization; Silica coatings; Nanomagnetics
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