TY  - JOUR
AU  - Tadić, Marin
AU  - Milošević, Irena
AU  - Kralj, Slavko
AU  - Hanžel, Darko
AU  - Barudžija, Tanja
AU  - Motte, Laurence
AU  - Makovec, Darko
PY  - 2020
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/8824
AB  - A metastable ε-polymorph of iron(III) oxide (ε-Fe2O3) is a very attractive material from the technological, engineering, and scientific points of view. In comparison with other iron oxides, it is characterized by unusual magnetic properties and a giant coercivity of ~20 kOe, which is the largest value among metal oxides. The routine method of ε-Fe2O3 formation is based on the thermal annealing of maghemite (γ-Fe2O3) nanoparticles confined in a silica matrix where the ε-Fe2O3 appears as an intermediate phase between the maghemite and an α-polymorph (α-Fe2O3) hematite (γ→ε→α pathway). In this study, it is demonstrated that the ε→α transformation can be reversed when hematite nanoparticles with an anisotropic hollow morphology are annealed above 600 °C. The observed reversal of the phase stability is explained in terms of an increased nanoparticle surface area and surface energy related to the hollow structure. This study demonstrates the applicability of surface-induced phase transformation to stabilize and control ε-Fe2O3 nanostructures with anisotropic shape and high coercivity ~1600 kA/m that is one of the key properties of functional magnetic materials for information processing and storage. The understanding of ε-Fe2O3 formation mechanism can provide a new viewpoint and guidance for designing metastable polymorphs and applicative properties. © 2020 Acta Materialia Inc.
T2  - Acta Materialia
T1  - Surface-induced reversal of a phase transformation for the synthesis of ε-Fe2O3 nanoparticles with high coercivity
VL  - 188
SP  - 16
EP  - 22
DO  - 10.1016/j.actamat.2020.01.058
ER  - 

@article{
author = "Tadić, Marin and Milošević, Irena and Kralj, Slavko and Hanžel, Darko and Barudžija, Tanja and Motte, Laurence and Makovec, Darko",
year = "2020",
abstract = "A metastable ε-polymorph of iron(III) oxide (ε-Fe2O3) is a very attractive material from the technological, engineering, and scientific points of view. In comparison with other iron oxides, it is characterized by unusual magnetic properties and a giant coercivity of ~20 kOe, which is the largest value among metal oxides. The routine method of ε-Fe2O3 formation is based on the thermal annealing of maghemite (γ-Fe2O3) nanoparticles confined in a silica matrix where the ε-Fe2O3 appears as an intermediate phase between the maghemite and an α-polymorph (α-Fe2O3) hematite (γ→ε→α pathway). In this study, it is demonstrated that the ε→α transformation can be reversed when hematite nanoparticles with an anisotropic hollow morphology are annealed above 600 °C. The observed reversal of the phase stability is explained in terms of an increased nanoparticle surface area and surface energy related to the hollow structure. This study demonstrates the applicability of surface-induced phase transformation to stabilize and control ε-Fe2O3 nanostructures with anisotropic shape and high coercivity ~1600 kA/m that is one of the key properties of functional magnetic materials for information processing and storage. The understanding of ε-Fe2O3 formation mechanism can provide a new viewpoint and guidance for designing metastable polymorphs and applicative properties. © 2020 Acta Materialia Inc.",
journal = "Acta Materialia",
title = "Surface-induced reversal of a phase transformation for the synthesis of ε-Fe2O3 nanoparticles with high coercivity",
volume = "188",
pages = "16-22",
doi = "10.1016/j.actamat.2020.01.058"
}

Tadić, M., Milošević, I., Kralj, S., Hanžel, D., Barudžija, T., Motte, L.,& Makovec, D.. (2020). Surface-induced reversal of a phase transformation for the synthesis of ε-Fe2O3 nanoparticles with high coercivity. in Acta Materialia, 188, 16-22.
https://doi.org/10.1016/j.actamat.2020.01.058

Tadić M, Milošević I, Kralj S, Hanžel D, Barudžija T, Motte L, Makovec D. Surface-induced reversal of a phase transformation for the synthesis of ε-Fe2O3 nanoparticles with high coercivity. in Acta Materialia. 2020;188:16-22.
doi:10.1016/j.actamat.2020.01.058 .

Tadić, Marin, Milošević, Irena, Kralj, Slavko, Hanžel, Darko, Barudžija, Tanja, Motte, Laurence, Makovec, Darko, "Surface-induced reversal of a phase transformation for the synthesis of ε-Fe2O3 nanoparticles with high coercivity" in Acta Materialia, 188 (2020):16-22,
https://doi.org/10.1016/j.actamat.2020.01.058 . .

TY  - JOUR
AU  - Darmanović, Darinka
AU  - Shcherbakov, Igor N.
AU  - Duboc, Carole
AU  - Spasojević, Vojislav
AU  - Hanžel, Darko
AU  - Anđelković, Katarina
AU  - Radanović, Dušanka D.
AU  - Turel, Iztok
AU  - Milenković, Milica R.
AU  - Gruden, Maja
AU  - Čobeljić, Božidar
AU  - Zlatar, Matija
PY  - 2019
UR  - http://cherry.chem.bg.ac.rs/handle/123456789/3855
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/8751
AB  - Magnetic anisotropy in pentagonal bipyramidal complexes of Co(II) (1 and 2), Fe(III) (3 and 4), and Ni(II) (5) with a 2,2′-[2,6-pyridinediylbis(ethylidyne-1-hydrazinyl-2-ylidene)]bis[N,N,N-trimethyl-2-oxoethanaminium] equatorial ligand and isothiocyanato axial ligands has been investigated by magnetic susceptibility measurements, powder X-band electron paramagnetic resonance (EPR) spectroscopy, Mössbauer spectroscopy, ab initio, and ligand-field density functional theory (LFDFT) calculations. The studied complexes display three distinct types of magnetic anisotropy. Co(II) complexes (1 and 2) show an easy plane anisotropy with large and positive D values and negligible rhombicity. The Ni(II) complex (5) has uniaxial magnetic anisotropy with a negative D value. Fe(III) complexes (3 and 4) have small zero-field splitting (ZFS) parameters. Theoretical modeling is used to rationalize the magnetic anisotropy in these systems and to identify the most important excited states that are responsible for the zero-field splitting. These excitations are a consequence of the electronic structure of the central metal ion in ideal pentagonal bipyramidal coordination.
T2  - The Journal of Physical Chemistry C
T1  - Combined Experimental and Theoretical Investigation of the Origin of Magnetic Anisotropy in Pentagonal Bipyramidal Isothiocyanato Co(II), Ni(II), and Fe(III) Complexes with Quaternary-Ammonium-Functionalized 2,6-Diacetylpyridine Bisacylhydrazone
VL  - 123
IS  - 51
SP  - 31142
EP  - 31155
DO  - 10.1021/acs.jpcc.9b08066
ER  - 

@article{
author = "Darmanović, Darinka and Shcherbakov, Igor N. and Duboc, Carole and Spasojević, Vojislav and Hanžel, Darko and Anđelković, Katarina and Radanović, Dušanka D. and Turel, Iztok and Milenković, Milica R. and Gruden, Maja and Čobeljić, Božidar and Zlatar, Matija",
year = "2019",
abstract = "Magnetic anisotropy in pentagonal bipyramidal complexes of Co(II) (1 and 2), Fe(III) (3 and 4), and Ni(II) (5) with a 2,2′-[2,6-pyridinediylbis(ethylidyne-1-hydrazinyl-2-ylidene)]bis[N,N,N-trimethyl-2-oxoethanaminium] equatorial ligand and isothiocyanato axial ligands has been investigated by magnetic susceptibility measurements, powder X-band electron paramagnetic resonance (EPR) spectroscopy, Mössbauer spectroscopy, ab initio, and ligand-field density functional theory (LFDFT) calculations. The studied complexes display three distinct types of magnetic anisotropy. Co(II) complexes (1 and 2) show an easy plane anisotropy with large and positive D values and negligible rhombicity. The Ni(II) complex (5) has uniaxial magnetic anisotropy with a negative D value. Fe(III) complexes (3 and 4) have small zero-field splitting (ZFS) parameters. Theoretical modeling is used to rationalize the magnetic anisotropy in these systems and to identify the most important excited states that are responsible for the zero-field splitting. These excitations are a consequence of the electronic structure of the central metal ion in ideal pentagonal bipyramidal coordination.",
journal = "The Journal of Physical Chemistry C",
title = "Combined Experimental and Theoretical Investigation of the Origin of Magnetic Anisotropy in Pentagonal Bipyramidal Isothiocyanato Co(II), Ni(II), and Fe(III) Complexes with Quaternary-Ammonium-Functionalized 2,6-Diacetylpyridine Bisacylhydrazone",
volume = "123",
number = "51",
pages = "31142-31155",
doi = "10.1021/acs.jpcc.9b08066"
}

Darmanović, D., Shcherbakov, I. N., Duboc, C., Spasojević, V., Hanžel, D., Anđelković, K., Radanović, D. D., Turel, I., Milenković, M. R., Gruden, M., Čobeljić, B.,& Zlatar, M.. (2019). Combined Experimental and Theoretical Investigation of the Origin of Magnetic Anisotropy in Pentagonal Bipyramidal Isothiocyanato Co(II), Ni(II), and Fe(III) Complexes with Quaternary-Ammonium-Functionalized 2,6-Diacetylpyridine Bisacylhydrazone. in The Journal of Physical Chemistry C, 123(51), 31142-31155.
https://doi.org/10.1021/acs.jpcc.9b08066

Darmanović D, Shcherbakov IN, Duboc C, Spasojević V, Hanžel D, Anđelković K, Radanović DD, Turel I, Milenković MR, Gruden M, Čobeljić B, Zlatar M. Combined Experimental and Theoretical Investigation of the Origin of Magnetic Anisotropy in Pentagonal Bipyramidal Isothiocyanato Co(II), Ni(II), and Fe(III) Complexes with Quaternary-Ammonium-Functionalized 2,6-Diacetylpyridine Bisacylhydrazone. in The Journal of Physical Chemistry C. 2019;123(51):31142-31155.
doi:10.1021/acs.jpcc.9b08066 .

Darmanović, Darinka, Shcherbakov, Igor N., Duboc, Carole, Spasojević, Vojislav, Hanžel, Darko, Anđelković, Katarina, Radanović, Dušanka D., Turel, Iztok, Milenković, Milica R., Gruden, Maja, Čobeljić, Božidar, Zlatar, Matija, "Combined Experimental and Theoretical Investigation of the Origin of Magnetic Anisotropy in Pentagonal Bipyramidal Isothiocyanato Co(II), Ni(II), and Fe(III) Complexes with Quaternary-Ammonium-Functionalized 2,6-Diacetylpyridine Bisacylhydrazone" in The Journal of Physical Chemistry C, 123, no. 51 (2019):31142-31155,
https://doi.org/10.1021/acs.jpcc.9b08066 . .

TY  - JOUR
AU  - Tadić, Marin
AU  - Kralj, Slavko
AU  - Jagodič, Marko
AU  - Hanžel, Darko
AU  - Makovec, Darko
PY  - 2014
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/59
AB  - The aim of this work is to present the magnetic properties of novel superparamagnetic-iNANOvative (TM)vertical bar silica nanoparticle clusters. A TEM analysis showed that these nanoparticle clusters, approximately 80 nm in size, contained an assembly of maghemite nanoparticles in the core and an amorphous silica shell. The maghemite nanoparticles in the core were approximately 10 nm in size, whereas the uniform silica shell was approximately 15-nm thick. The number of magnetic nanoparticles that were densely packed in the core of the single nanocluster was estimated to be approximately 67, resulting in a high magnetic moment for the single nanocluster of m(nc) similar to 1.2 x 10(6) mu(B). This magnetic property of the nanoparticle cluster is advantageous for its easy manipulation using an external magnetic field, for example, in biomedical applications, such as drug delivery, or for magnetic separation in biotechnology. The magnetic properties of the iNANOvative (TM)vertical bar silica nanoparticle clusters were systematically studied, with a special focus on the influence of the magnetic interactions between the nanoparticles in the core. For comparison, the nanoparticle clusters were annealed for 3 h at 300 degrees C in air. The annealing had no influence on the nanoparticles size and phase; however, it had a unique effect on the magnetic properties, i.e., a decrease of the blocking temperature and a weakening of the inter-particle interactions. We believe that this surprising observation is related to the thermal decomposition of the organic surfactant on the surfaces of the nanoparticles at the high annealing temperatures, which resulted in the formation of amorphous carbon inside the nanocluster. (C) 2014 Elsevier B.V. All rights reserved.
T2  - Applied Surface Science
T1  - Magnetic properties of novel superparamagnetic iron oxide nanoclusters and their peculiarity under annealing treatment
VL  - 322
SP  - 255
EP  - 264
DO  - 10.1016/j.apsusc.2014.09.181
ER  - 

@article{
author = "Tadić, Marin and Kralj, Slavko and Jagodič, Marko and Hanžel, Darko and Makovec, Darko",
year = "2014",
abstract = "The aim of this work is to present the magnetic properties of novel superparamagnetic-iNANOvative (TM)vertical bar silica nanoparticle clusters. A TEM analysis showed that these nanoparticle clusters, approximately 80 nm in size, contained an assembly of maghemite nanoparticles in the core and an amorphous silica shell. The maghemite nanoparticles in the core were approximately 10 nm in size, whereas the uniform silica shell was approximately 15-nm thick. The number of magnetic nanoparticles that were densely packed in the core of the single nanocluster was estimated to be approximately 67, resulting in a high magnetic moment for the single nanocluster of m(nc) similar to 1.2 x 10(6) mu(B). This magnetic property of the nanoparticle cluster is advantageous for its easy manipulation using an external magnetic field, for example, in biomedical applications, such as drug delivery, or for magnetic separation in biotechnology. The magnetic properties of the iNANOvative (TM)vertical bar silica nanoparticle clusters were systematically studied, with a special focus on the influence of the magnetic interactions between the nanoparticles in the core. For comparison, the nanoparticle clusters were annealed for 3 h at 300 degrees C in air. The annealing had no influence on the nanoparticles size and phase; however, it had a unique effect on the magnetic properties, i.e., a decrease of the blocking temperature and a weakening of the inter-particle interactions. We believe that this surprising observation is related to the thermal decomposition of the organic surfactant on the surfaces of the nanoparticles at the high annealing temperatures, which resulted in the formation of amorphous carbon inside the nanocluster. (C) 2014 Elsevier B.V. All rights reserved.",
journal = "Applied Surface Science",
title = "Magnetic properties of novel superparamagnetic iron oxide nanoclusters and their peculiarity under annealing treatment",
volume = "322",
pages = "255-264",
doi = "10.1016/j.apsusc.2014.09.181"
}

Tadić, M., Kralj, S., Jagodič, M., Hanžel, D.,& Makovec, D.. (2014). Magnetic properties of novel superparamagnetic iron oxide nanoclusters and their peculiarity under annealing treatment. in Applied Surface Science, 322, 255-264.
https://doi.org/10.1016/j.apsusc.2014.09.181

Tadić M, Kralj S, Jagodič M, Hanžel D, Makovec D. Magnetic properties of novel superparamagnetic iron oxide nanoclusters and their peculiarity under annealing treatment. in Applied Surface Science. 2014;322:255-264.
doi:10.1016/j.apsusc.2014.09.181 .

Tadić, Marin, Kralj, Slavko, Jagodič, Marko, Hanžel, Darko, Makovec, Darko, "Magnetic properties of novel superparamagnetic iron oxide nanoclusters and their peculiarity under annealing treatment" in Applied Surface Science, 322 (2014):255-264,
https://doi.org/10.1016/j.apsusc.2014.09.181 . .

TY  - JOUR
AU  - Blinc, R.
AU  - Cevc, P.
AU  - Potocnik, A.
AU  - Zemva, B.
AU  - Goreshnik, E.
AU  - Hanžel, Darko
AU  - Gregorovic, A.
AU  - Trontelj, Z.
AU  - Jagličić, Zvonko
AU  - Laguta, V.
AU  - Perović, Marija M.
AU  - Dalal, N. S.
AU  - Scott, J. F.
PY  - 2010
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/3920
AB  - The local electronic and structural as well as the macroscopic magnetic properties of K3Cr2Fe3F15 have been studied between room temperature and 4 K. The system has been found to be isostructural with ferroelectric and weakly ferrimagnetic K3Fe5F15 above the ferroelectric transition temperature T-c. The X-band and 216 GHz Cr3+ electron paramagnetic resonance (EPR) spectra as well as the magnetic susceptibility and Moumlssbauer data show the existence of two magnetic relaxor type transitions around 37 and 17 K. The K-39 magic angle sample spinning NMR, EPR, and the Moumlssbauer data further demonstrate the existence of two nonequivalent Fe, Cr, and K sites in the unit cell as well as the presence of rapid exchange at higher temperatures. The observation of the Fe2+ EPR and Moumlssbauer spectra shows that the Fe2+ ion is in a high spin state.
T2  - Journal of Applied Physics
T1  - Magnetic properties of multiferroic K3Cr2Fe3F15
VL  - 107
IS  - 4
DO  - 10.1063/1.3309205
ER  - 

@article{
author = "Blinc, R. and Cevc, P. and Potocnik, A. and Zemva, B. and Goreshnik, E. and Hanžel, Darko and Gregorovic, A. and Trontelj, Z. and Jagličić, Zvonko and Laguta, V. and Perović, Marija M. and Dalal, N. S. and Scott, J. F.",
year = "2010",
abstract = "The local electronic and structural as well as the macroscopic magnetic properties of K3Cr2Fe3F15 have been studied between room temperature and 4 K. The system has been found to be isostructural with ferroelectric and weakly ferrimagnetic K3Fe5F15 above the ferroelectric transition temperature T-c. The X-band and 216 GHz Cr3+ electron paramagnetic resonance (EPR) spectra as well as the magnetic susceptibility and Moumlssbauer data show the existence of two magnetic relaxor type transitions around 37 and 17 K. The K-39 magic angle sample spinning NMR, EPR, and the Moumlssbauer data further demonstrate the existence of two nonequivalent Fe, Cr, and K sites in the unit cell as well as the presence of rapid exchange at higher temperatures. The observation of the Fe2+ EPR and Moumlssbauer spectra shows that the Fe2+ ion is in a high spin state.",
journal = "Journal of Applied Physics",
title = "Magnetic properties of multiferroic K3Cr2Fe3F15",
volume = "107",
number = "4",
doi = "10.1063/1.3309205"
}

Blinc, R., Cevc, P., Potocnik, A., Zemva, B., Goreshnik, E., Hanžel, D., Gregorovic, A., Trontelj, Z., Jagličić, Z., Laguta, V., Perović, M. M., Dalal, N. S.,& Scott, J. F.. (2010). Magnetic properties of multiferroic K3Cr2Fe3F15. in Journal of Applied Physics, 107(4).
https://doi.org/10.1063/1.3309205

Blinc R, Cevc P, Potocnik A, Zemva B, Goreshnik E, Hanžel D, Gregorovic A, Trontelj Z, Jagličić Z, Laguta V, Perović MM, Dalal NS, Scott JF. Magnetic properties of multiferroic K3Cr2Fe3F15. in Journal of Applied Physics. 2010;107(4).
doi:10.1063/1.3309205 .

Blinc, R., Cevc, P., Potocnik, A., Zemva, B., Goreshnik, E., Hanžel, Darko, Gregorovic, A., Trontelj, Z., Jagličić, Zvonko, Laguta, V., Perović, Marija M., Dalal, N. S., Scott, J. F., "Magnetic properties of multiferroic K3Cr2Fe3F15" in Journal of Applied Physics, 107, no. 4 (2010),
https://doi.org/10.1063/1.3309205 . .