TY  - JOUR
AU  - Tadić, Marin
AU  - Nikolic, Dobrica
AU  - Panjan, Matjaž
AU  - Blake, Graeme R.
PY  - 2015
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/734
AB  - Crystalline nickel oxide (NiO) nanoparticles dispersed in an amorphous silica matrix have been prepared by a sol-gel combustion synthesis method. The sample was characterized using X-ray powder diffraction, energy-dispersive X-ray spectroscopy, scanning electron microscopy, transmission electron microscopy and superconducting quantum interference device magnetometry. The nanoparticles were spherical with an average size of about 5 nm and narrow particle size distribution. The magnetization measurements revealed two maxima in the zero-field cooled magnetization curve at 5 K and 56 K. An analysis of DC and AC magnetic susceptibility measurements revealed that the higher temperature maximum corresponded to the onset of antiferromagnetic ordering within the particles. The Neel temperature of T-N = 56 K is much lower than in bulk NiO. The 5 K maximum corresponded to the particle blocking temperature TB. The frequency dependence of TB was successfully fitted using the Vogel-Fulcher law, indicating the presence of weak inter-particle interactions (C-1 = 0.08 and C-2 = 0.76). A Curie-Weiss law fit to the magnetic susceptibility above T-N revealed antiferromagnetic exchange interactions with a Curie-Weiss temperature of theta = 24 K and an effective magnetic moment of mu(eff) = 2.87 mu(B) per NiO unit. We conclude that these magnetic properties can be attributed to the smallness of the NiO nanoparticles and to crystal lattice defects. (C) 2015 Elsevier B.V. All rights reserved.
T2  - Journal of Alloys and Compounds
T1  - Magnetic properties of NiO (nickel oxide) nanoparticles: Blocking temperature and Neel temperature
VL  - 647
SP  - 1061
EP  - 1068
DO  - 10.1016/j.jallcom.2015.06.027
ER  - 

@article{
author = "Tadić, Marin and Nikolic, Dobrica and Panjan, Matjaž and Blake, Graeme R.",
year = "2015",
abstract = "Crystalline nickel oxide (NiO) nanoparticles dispersed in an amorphous silica matrix have been prepared by a sol-gel combustion synthesis method. The sample was characterized using X-ray powder diffraction, energy-dispersive X-ray spectroscopy, scanning electron microscopy, transmission electron microscopy and superconducting quantum interference device magnetometry. The nanoparticles were spherical with an average size of about 5 nm and narrow particle size distribution. The magnetization measurements revealed two maxima in the zero-field cooled magnetization curve at 5 K and 56 K. An analysis of DC and AC magnetic susceptibility measurements revealed that the higher temperature maximum corresponded to the onset of antiferromagnetic ordering within the particles. The Neel temperature of T-N = 56 K is much lower than in bulk NiO. The 5 K maximum corresponded to the particle blocking temperature TB. The frequency dependence of TB was successfully fitted using the Vogel-Fulcher law, indicating the presence of weak inter-particle interactions (C-1 = 0.08 and C-2 = 0.76). A Curie-Weiss law fit to the magnetic susceptibility above T-N revealed antiferromagnetic exchange interactions with a Curie-Weiss temperature of theta = 24 K and an effective magnetic moment of mu(eff) = 2.87 mu(B) per NiO unit. We conclude that these magnetic properties can be attributed to the smallness of the NiO nanoparticles and to crystal lattice defects. (C) 2015 Elsevier B.V. All rights reserved.",
journal = "Journal of Alloys and Compounds",
title = "Magnetic properties of NiO (nickel oxide) nanoparticles: Blocking temperature and Neel temperature",
volume = "647",
pages = "1061-1068",
doi = "10.1016/j.jallcom.2015.06.027"
}

Tadić, M., Nikolic, D., Panjan, M.,& Blake, G. R.. (2015). Magnetic properties of NiO (nickel oxide) nanoparticles: Blocking temperature and Neel temperature. in Journal of Alloys and Compounds, 647, 1061-1068.
https://doi.org/10.1016/j.jallcom.2015.06.027

Tadić M, Nikolic D, Panjan M, Blake GR. Magnetic properties of NiO (nickel oxide) nanoparticles: Blocking temperature and Neel temperature. in Journal of Alloys and Compounds. 2015;647:1061-1068.
doi:10.1016/j.jallcom.2015.06.027 .

Tadić, Marin, Nikolic, Dobrica, Panjan, Matjaž, Blake, Graeme R., "Magnetic properties of NiO (nickel oxide) nanoparticles: Blocking temperature and Neel temperature" in Journal of Alloys and Compounds, 647 (2015):1061-1068,
https://doi.org/10.1016/j.jallcom.2015.06.027 . .

TY  - JOUR
AU  - Nikolic, Dobrica
AU  - Panjan, Matjaž
AU  - Blake, Graeme R.
AU  - Tadić, Marin
PY  - 2015
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/717
AB  - We show that annealing at high temperatures has a significant effect on the structural and magnetic properties of NiO/SiO2 nanostructures synthesized by a sol-gel combustion method. Samples underwent heat treatments at 500 degrees C, 800 degrees C, 950 degrees C and 1100 degrees C. As compared to the 500 degrees C sample, the 800 degrees C sample showed the following magnetic properties: much higher irreversibility temperature, a significantly broadened zero-field-cooled (ZFC) magnetization maximum, a decrease of the ZFC magnetization, an increase of the coercivity, and weaker inter-particle interactions. These changes can be attributed to agglomeration of nanoparticles in part of the sample. We believe that this agglomeration can be explained by the removal of thin regions of silica that separate nanoparticles in close proximity during the annealing process at 800 degrees C. Magnetic measurements for the 1100 sample reveal both an abrupt increase in size of the NiO nanoparticles, which is confirmed by TEM and XRPD measurements, and an increase in inter-particle interaction strength. (C) 2015 Elsevier Ltd. All rights reserved.
T2  - Journal of the European Ceramic Society
T1  - Annealing-dependent structural and magnetic properties of nickel oxide (NiO) nanoparticles in a silica matrix
VL  - 35
IS  - 14
SP  - 3843
EP  - 3852
DO  - 10.1016/j.jeurceramsoc.2015.06.024
ER  - 

@article{
author = "Nikolic, Dobrica and Panjan, Matjaž and Blake, Graeme R. and Tadić, Marin",
year = "2015",
abstract = "We show that annealing at high temperatures has a significant effect on the structural and magnetic properties of NiO/SiO2 nanostructures synthesized by a sol-gel combustion method. Samples underwent heat treatments at 500 degrees C, 800 degrees C, 950 degrees C and 1100 degrees C. As compared to the 500 degrees C sample, the 800 degrees C sample showed the following magnetic properties: much higher irreversibility temperature, a significantly broadened zero-field-cooled (ZFC) magnetization maximum, a decrease of the ZFC magnetization, an increase of the coercivity, and weaker inter-particle interactions. These changes can be attributed to agglomeration of nanoparticles in part of the sample. We believe that this agglomeration can be explained by the removal of thin regions of silica that separate nanoparticles in close proximity during the annealing process at 800 degrees C. Magnetic measurements for the 1100 sample reveal both an abrupt increase in size of the NiO nanoparticles, which is confirmed by TEM and XRPD measurements, and an increase in inter-particle interaction strength. (C) 2015 Elsevier Ltd. All rights reserved.",
journal = "Journal of the European Ceramic Society",
title = "Annealing-dependent structural and magnetic properties of nickel oxide (NiO) nanoparticles in a silica matrix",
volume = "35",
number = "14",
pages = "3843-3852",
doi = "10.1016/j.jeurceramsoc.2015.06.024"
}

Nikolic, D., Panjan, M., Blake, G. R.,& Tadić, M.. (2015). Annealing-dependent structural and magnetic properties of nickel oxide (NiO) nanoparticles in a silica matrix. in Journal of the European Ceramic Society, 35(14), 3843-3852.
https://doi.org/10.1016/j.jeurceramsoc.2015.06.024

Nikolic D, Panjan M, Blake GR, Tadić M. Annealing-dependent structural and magnetic properties of nickel oxide (NiO) nanoparticles in a silica matrix. in Journal of the European Ceramic Society. 2015;35(14):3843-3852.
doi:10.1016/j.jeurceramsoc.2015.06.024 .

Nikolic, Dobrica, Panjan, Matjaž, Blake, Graeme R., Tadić, Marin, "Annealing-dependent structural and magnetic properties of nickel oxide (NiO) nanoparticles in a silica matrix" in Journal of the European Ceramic Society, 35, no. 14 (2015):3843-3852,
https://doi.org/10.1016/j.jeurceramsoc.2015.06.024 . .