Sol-gel combustion synthesis, particle shape analysis and magnetic properties of hematite (alpha-Fe2O3) nanoparticles embedded in an amorphous silica matrix
Abstract
We report the synthesis and magnetic properties of hematite/amorphous silica nanostructures. Raman spectroscopy showed the formation of a hematite phase. A transmission electron microscopy (TEM) revealed spherically shaped hematite nanoparticles, well-dispersed in an amorphous silica matrix. In order to quantitatively describe morphological properties of nanoparticles, we use the circularity of shapes as a measure of how circular a shape is. Diameters of about 5 nm and a narrow size distribution of nanoparticles are observed. The obtained hematite nanoparticles exhibit superparamagnetic properties at room temperature (SPION). The sample does not display the Morin transition. The FC hysteresis loop at 5 K has shown an exchange bias effect. These results have been compared to those previously reported for alpha-Fe2O3/SiO2 nanosystems in the literature. These comparisons reveal that the sol-gel combustion method yields hematite nanoparticles with a higher magnetization and magnetic moment.... These data indicate the existence of an additional factor that contributes to magnetization. We suggest that the increased magnetization is due to an increased number of the surface spins caused by the breaking of large numbers of exchange bonds between surface atoms (disordered structure). This leads to an increase in the magnetic moment per a hematite nanoparticle and an exchange bias effect. We have concluded that the combustion-related part of this synthesis method enhances surface effects, i.e. it promotes the breaking of bonds and surface disordered layers, which results in these magnetic properties. Such interesting structural and magnetic properties of hematite might be important in future practical applications and fundamental research. (C) 2015 Elsevier B.V. All rights reserved.
Keywords:
Iron oxide / Hematite (alpha-Fe2O3) / Amorphous silica / Surface effects / Superparamagnetism (SPION) / Magnetic propertiesSource:
Applied Surface Science, 2016, 362, 380-386Publisher:
- Elsevier
Funding / projects:
- Magnetic and radionuclide labeled nanostructured materials for medical applications (RS-MESTD-Integrated and Interdisciplinary Research (IIR or III)-45015)
- Ministry of Higher Education, Science and Technology of the Republic of Slovenia within the National Research Program [L2-5470]
DOI: 10.1016/j.apsusc.2015.11.238
ISSN: 0169-4332; 1873-5584
WoS: 000368657900052
Scopus: 2-s2.0-84959537966
Collections
Institution/Community
VinčaTY - JOUR AU - Kopanja, Lazar AU - Milošević, Irena AU - Panjan, Matjaž AU - Damnjanović, Vesna AU - Tadić, Marin PY - 2016 UR - https://vinar.vin.bg.ac.rs/handle/123456789/901 AB - We report the synthesis and magnetic properties of hematite/amorphous silica nanostructures. Raman spectroscopy showed the formation of a hematite phase. A transmission electron microscopy (TEM) revealed spherically shaped hematite nanoparticles, well-dispersed in an amorphous silica matrix. In order to quantitatively describe morphological properties of nanoparticles, we use the circularity of shapes as a measure of how circular a shape is. Diameters of about 5 nm and a narrow size distribution of nanoparticles are observed. The obtained hematite nanoparticles exhibit superparamagnetic properties at room temperature (SPION). The sample does not display the Morin transition. The FC hysteresis loop at 5 K has shown an exchange bias effect. These results have been compared to those previously reported for alpha-Fe2O3/SiO2 nanosystems in the literature. These comparisons reveal that the sol-gel combustion method yields hematite nanoparticles with a higher magnetization and magnetic moment. These data indicate the existence of an additional factor that contributes to magnetization. We suggest that the increased magnetization is due to an increased number of the surface spins caused by the breaking of large numbers of exchange bonds between surface atoms (disordered structure). This leads to an increase in the magnetic moment per a hematite nanoparticle and an exchange bias effect. We have concluded that the combustion-related part of this synthesis method enhances surface effects, i.e. it promotes the breaking of bonds and surface disordered layers, which results in these magnetic properties. Such interesting structural and magnetic properties of hematite might be important in future practical applications and fundamental research. (C) 2015 Elsevier B.V. All rights reserved. PB - Elsevier T2 - Applied Surface Science T1 - Sol-gel combustion synthesis, particle shape analysis and magnetic properties of hematite (alpha-Fe2O3) nanoparticles embedded in an amorphous silica matrix VL - 362 SP - 380 EP - 386 DO - 10.1016/j.apsusc.2015.11.238 ER -
@article{ author = "Kopanja, Lazar and Milošević, Irena and Panjan, Matjaž and Damnjanović, Vesna and Tadić, Marin", year = "2016", abstract = "We report the synthesis and magnetic properties of hematite/amorphous silica nanostructures. Raman spectroscopy showed the formation of a hematite phase. A transmission electron microscopy (TEM) revealed spherically shaped hematite nanoparticles, well-dispersed in an amorphous silica matrix. In order to quantitatively describe morphological properties of nanoparticles, we use the circularity of shapes as a measure of how circular a shape is. Diameters of about 5 nm and a narrow size distribution of nanoparticles are observed. The obtained hematite nanoparticles exhibit superparamagnetic properties at room temperature (SPION). The sample does not display the Morin transition. The FC hysteresis loop at 5 K has shown an exchange bias effect. These results have been compared to those previously reported for alpha-Fe2O3/SiO2 nanosystems in the literature. These comparisons reveal that the sol-gel combustion method yields hematite nanoparticles with a higher magnetization and magnetic moment. These data indicate the existence of an additional factor that contributes to magnetization. We suggest that the increased magnetization is due to an increased number of the surface spins caused by the breaking of large numbers of exchange bonds between surface atoms (disordered structure). This leads to an increase in the magnetic moment per a hematite nanoparticle and an exchange bias effect. We have concluded that the combustion-related part of this synthesis method enhances surface effects, i.e. it promotes the breaking of bonds and surface disordered layers, which results in these magnetic properties. Such interesting structural and magnetic properties of hematite might be important in future practical applications and fundamental research. (C) 2015 Elsevier B.V. All rights reserved.", publisher = "Elsevier", journal = "Applied Surface Science", title = "Sol-gel combustion synthesis, particle shape analysis and magnetic properties of hematite (alpha-Fe2O3) nanoparticles embedded in an amorphous silica matrix", volume = "362", pages = "380-386", doi = "10.1016/j.apsusc.2015.11.238" }
Kopanja, L., Milošević, I., Panjan, M., Damnjanović, V.,& Tadić, M.. (2016). Sol-gel combustion synthesis, particle shape analysis and magnetic properties of hematite (alpha-Fe2O3) nanoparticles embedded in an amorphous silica matrix. in Applied Surface Science Elsevier., 362, 380-386. https://doi.org/10.1016/j.apsusc.2015.11.238
Kopanja L, Milošević I, Panjan M, Damnjanović V, Tadić M. Sol-gel combustion synthesis, particle shape analysis and magnetic properties of hematite (alpha-Fe2O3) nanoparticles embedded in an amorphous silica matrix. in Applied Surface Science. 2016;362:380-386. doi:10.1016/j.apsusc.2015.11.238 .
Kopanja, Lazar, Milošević, Irena, Panjan, Matjaž, Damnjanović, Vesna, Tadić, Marin, "Sol-gel combustion synthesis, particle shape analysis and magnetic properties of hematite (alpha-Fe2O3) nanoparticles embedded in an amorphous silica matrix" in Applied Surface Science, 362 (2016):380-386, https://doi.org/10.1016/j.apsusc.2015.11.238 . .