Cesare Oliva

University of Milan

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University of Milan

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Cesare Oliva has a total of 199 co-authors. Here are the top co-authors by number of shared publications:

Lucio Forni
Dipartimento di Chimica, Università degli Studi di Milano and CNR-ISTM, Via C. Golgi 19, 20133 Milano, Italy
14 shared publications
L. Forni
Dip. Chimica Fisica ed Elettrochimica, Università di Milano, v. C. Golgi, 19, Milano, Italy
11 shared publications
Marco Scavini
Dipartimento di Chimica, Università degli Studi di Milano, Via Golgi 19, 20133 Milan, Italy
11 shared publications
Mattia Allieta
Dipartimento di Chimica, Università degli Studi di Milano, via Golgi 19, 20133 Milano, Italy
7 shared publications
Aldo Gamba
6 shared publications
Alessandro Ponti
Laboratorio di Nanotecnologie Istituto di Scienze e Tecnologie Chimiche “Giulio Natta” (SCITEC) Consiglio Nazionale delle Ricerche Via Fantoli 16/15 Milano 20138 Italy
6 shared publications

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Cited by 76
- 30 April 2020
- Published by MDPI AG in Nanomaterials
Local Structure and Magnetism of Fe₂O₃ Maghemite Nanocrystals: The Role of Crystal Dimension
by Mauro Coduri, Paolo Masala, Lucia Del Bianco, Federico Spizzo, Davide Ceresoli, Carlo Castellano, Serena Cappelli, Cesare Oliva, Stefano Checchia, Mattia Allieta, et al.
Here we report on the impact of reducing the crystalline size on the structural and magnetic properties of γ-Fe₂O₃ maghemite nanoparticles. A set of polycrystalline specimens with crystallite size ranging from ~2 to ~50 nm was obtained combining microwave plasma synthesis and commercial samples. Crystallite size was derived by electron microscopy and synchrotron powder diffraction, which was used also to investigate the crystallographic structure. The local atomic structure was inquired combining pair distribution function (PDF) and X-ray absorption spectroscopy (XAS). PDF revealed that reducing the crystal dimension induces the depletion of the amount of Fe tetrahedral sites. XAS confirmed significant bond distance expansion and a loose Fe-Fe connectivity between octahedral and tetrahedral sites. Molecular dynamics revealed important surface effects, whose implementation in PDF reproduces the first shells of experimental curves. The structural disorder affects the magnetic properties more and more with decreasing the nanoparticle size. In particular, the saturation magnetization reduces, revealing a spin canting effect. Moreover, a large effective magnetic anisotropy is measured at low temperature together with an exchange bias effect, a behavior that we related to the existence of a highly disordered glassy magnetic phase.
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- 30 April 2020
- Published by MDPI AG in Nanomaterials
Open Access
Local Structure and Magnetism of Fe₂O₃ Maghemite Nanocrystals: The Role of Crystal Dimension
by Mauro Coduri, Paolo Masala, Lucia Del Bianco, Federico Spizzo, Davide Ceresoli, Carlo Castellano, Serena Cappelli, Cesare Oliva, Stefano Checchia, Mattia Allieta, et al.
Here we report on the impact of reducing the crystalline size on the structural and magnetic properties of γ-Fe₂O₃ maghemite nanoparticles. A set of polycrystalline specimens with crystallite size ranging from ~2 to ~50 nm was obtained combining microwave plasma synthesis and commercial samples. Crystallite size was derived by electron microscopy and synchrotron powder diffraction, which was used also to investigate the crystallographic structure. The local atomic structure was inquired combining pair distribution function (PDF) and X-ray absorption spectroscopy (XAS). PDF revealed that reducing the crystal dimension induces the depletion of the amount of Fe tetrahedral sites. XAS confirmed significant bond distance expansion and a loose Fe-Fe connectivity between octahedral and tetrahedral sites. Molecular dynamics revealed important surface effects, whose implementation in PDF reproduces the first shells of experimental curves. The structural disorder affects the magnetic properties more and more with decreasing the nanoparticle size. In particular, the saturation magnetization reduces, revealing a spin canting effect. Moreover, a large effective magnetic anisotropy is measured at low temperature together with an exchange bias effect, a behavior that we related to the existence of a highly disordered glassy magnetic phase.
Cited by 76
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Cited by 1
- 10 November 2016
- Published by Springer Nature
Electron Spin Resonance Applied to Nanosized-Doped Oxides
by Cesare Oliva, Marco Scavini
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- 10 November 2016
- Published by Springer Nature
Electron Spin Resonance Applied to Nanosized-Doped Oxides
by Cesare Oliva, Marco Scavini
Cited by 1
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Cited by 6
- 11 August 2015
- Published by American Physical Society (APS) in Physical Review B
Interplay of structural and magnetic nanoscale phase separation in layered cobaltites
by M. Allieta, M. Scavini, A. Naldoni, M. Coduri, S. Cappelli, C. Oliva, S. Santangelo, C. Triolo, S. Patané, A. Lascialfari, et al.
We report on the structural, electronic, and magnetic phases of a previously unexplored region in the phase diagram of $GdBaC o_{2} {O_{5}}_{+ δ}$ ( $δ = 0.57$ and 0.63). Despite a homogenous average structure displayed by both the samples, the orthorhombic highly oxygenated $GdBaC o_{2} O_{5.63}$ shows clear signatures of structural nanoscale phase separation. By combining a pair distribution function with photoluminescence and electron spin resonance techniques, we found that the nanoscale phase separation is induced by an inhomogeneous distribution of ferromagnetic $C o^{3 +} - C o^{4 +}$ clusters embedded in an antiferromagnetic $C o^{3 +}$ -rich matrix. In addition, we uncovered a phase evolution involving the collapse of the orthorhombic strain below room temperature. The origin of this noncanonical transition seems to be associated with the interplay of the observed nanoscale phase separation and a new magnetic phase transition occurring below $T \sim 180 K$ .
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- 11 August 2015
- Published by American Physical Society (APS) in Physical Review B
Open Access
Interplay of structural and magnetic nanoscale phase separation in layered cobaltites
by M. Allieta, M. Scavini, A. Naldoni, M. Coduri, S. Cappelli, C. Oliva, S. Santangelo, C. Triolo, S. Patané, A. Lascialfari, et al.
We report on the structural, electronic, and magnetic phases of a previously unexplored region in the phase diagram of $GdBaC o_{2} {O_{5}}_{+ δ}$ ( $δ = 0.57$ and 0.63). Despite a homogenous average structure displayed by both the samples, the orthorhombic highly oxygenated $GdBaC o_{2} O_{5.63}$ shows clear signatures of structural nanoscale phase separation. By combining a pair distribution function with photoluminescence and electron spin resonance techniques, we found that the nanoscale phase separation is induced by an inhomogeneous distribution of ferromagnetic $C o^{3 +} - C o^{4 +}$ clusters embedded in an antiferromagnetic $C o^{3 +}$ -rich matrix. In addition, we uncovered a phase evolution involving the collapse of the orthorhombic strain below room temperature. The origin of this noncanonical transition seems to be associated with the interplay of the observed nanoscale phase separation and a new magnetic phase transition occurring below $T \sim 180 K$ .
Cited by 6
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Cited by 6
- 29 January 2015
- Published by Hindawi Limited in Journal of Spectroscopy
Electron Spin Resonance and Atomic Force Microscopy Study on Gadolinium Doped Ceria
by Cesare Oliva, Francesco Orsini, Serena Cappelli, Paolo Arosio, Mattia Allieta, Mauro Coduri, Marco Scavini
A combined electron spin resonance (ESR) and atomic force microscopy (AFM) study on Ce_1−xGd_xO_2−x/2samples is here presented, aimed at investigating the evolution of the ESR spectral shape as a function of $x$ in a wide composition range. At low $x (= 0.02)$ , the spectrum is composed of features at $g_{eff} \approx 2$ ; 2.8; 6. With increasing $x$ , this pattern merges into a single $(g_{eff} \approx 2)$ broad ESR curve, which assumes a Dysonian-shaped profile at $x \geq 0.5$ , whereas, at these $x$ values, AFM measurements show an increasing surface roughness. It is suggested that the last could cause the formation of surface polaritons at the origin of the particular ESR spectral profile observed at these high Gd doping levels.
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- 29 January 2015
- Published by Hindawi Limited in Journal of Spectroscopy
Open Access
Electron Spin Resonance and Atomic Force Microscopy Study on Gadolinium Doped Ceria
by Cesare Oliva, Francesco Orsini, Serena Cappelli, Paolo Arosio, Mattia Allieta, Mauro Coduri, Marco Scavini
A combined electron spin resonance (ESR) and atomic force microscopy (AFM) study on Ce_1−xGd_xO_2−x/2samples is here presented, aimed at investigating the evolution of the ESR spectral shape as a function of $x$ in a wide composition range. At low $x (= 0.02)$ , the spectrum is composed of features at $g_{eff} \approx 2$ ; 2.8; 6. With increasing $x$ , this pattern merges into a single $(g_{eff} \approx 2)$ broad ESR curve, which assumes a Dysonian-shaped profile at $x \geq 0.5$ , whereas, at these $x$ values, AFM measurements show an increasing surface roughness. It is suggested that the last could cause the formation of surface polaritons at the origin of the particular ESR spectral profile observed at these high Gd doping levels.
Cited by 6
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Cited by 51
- 25 September 2014
- Published by American Chemical Society (ACS) in The Journal of Physical Chemistry C
Unraveling the Cooperative Mechanism of Visible-Light Absorption in Bulk N,Nb Codoped TiO₂ Powders of Nanomaterials
by Chiara Marchiori, Giovanni Di Liberto, Guido Soliveri, Laura Loconte, Leonardo Lo Presti, Daniela Meroni, Michele Ceotto, Cesare Oliva, Serena Cappelli, Giuseppe Cappelletti, et al.
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- 25 September 2014
- Published by American Chemical Society (ACS) in The Journal of Physical Chemistry C
Unraveling the Cooperative Mechanism of Visible-Light Absorption in Bulk N,Nb Codoped TiO₂ Powders of Nanomaterials
by Chiara Marchiori, Giovanni Di Liberto, Guido Soliveri, Laura Loconte, Leonardo Lo Presti, Daniela Meroni, Michele Ceotto, Cesare Oliva, Serena Cappelli, Giuseppe Cappelletti, et al.
Cited by 51
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Cited by 16
- 4 December 2013
- Published by American Physical Society (APS) in Physical Review B
Charge ordering transition in GdBaCo $_{2}$ O $_{5}$ : Evidence of reentrant behavior
by M. Allieta, M. Scavini, L. Lo Presti, M. Coduri, L. Loconte, S. Cappelli, C. Oliva, P. Ghigna, P. Pattison, V. Scagnoli
We present a detailed study on the charge ordering transition in a GdBaCo $_{2}$ O $_{5.0}$ system by combining high-resolution synchrotron powder/single-crystal diffraction with electron paramagnetic resonance experiments as a function of temperature. We found a second-order structural phase transition at $T_{CO}$ = 247 K (Pmmm to Pmma) associated with the onset of long-range charge ordering. At $T_{\min}$ ≈ 1.2 $T_{CO,}$ the electron paramagnetic resonance linewidth rapidly broadens, providing evidence of antiferromagnetic spin fluctuations. This likely indicates that, analogously to manganites, the long-range antiferromagnetic order in GdBaCo $_{2}$ O $_{5.0}$ sets in at ≈ $T_{CO}$ . Pair distribution function analysis of diffraction data revealed signatures of structural inhomogeneities at low temperature. By comparing the average and local bond valences, we found that above $T_{CO}$ the local structure is consistent with a fully random occupation of Co $^{2 +}$ and Co $^{3 +}$ in a 1:1 ratio and with a complete charge ordering below $T_{CO}$ . Below $T$ ≈ 100 K the charge localization is partially melted at the local scale, suggesting a reentrant behavior of charge ordering. This result is supported by the weakening of superstructure reflections and the temperature evolution of electron paramagnetic resonance linewidth that is consistent with paramagnetic reentrant behavior reported in the GdBaCo $_{2}$ O $_{5.5}$ parent compound.
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- 4 December 2013
- Published by American Physical Society (APS) in Physical Review B
Charge ordering transition in GdBaCo $_{2}$ O $_{5}$ : Evidence of reentrant behavior
by M. Allieta, M. Scavini, L. Lo Presti, M. Coduri, L. Loconte, S. Cappelli, C. Oliva, P. Ghigna, P. Pattison, V. Scagnoli
We present a detailed study on the charge ordering transition in a GdBaCo $_{2}$ O $_{5.0}$ system by combining high-resolution synchrotron powder/single-crystal diffraction with electron paramagnetic resonance experiments as a function of temperature. We found a second-order structural phase transition at $T_{CO}$ = 247 K (Pmmm to Pmma) associated with the onset of long-range charge ordering. At $T_{\min}$ ≈ 1.2 $T_{CO,}$ the electron paramagnetic resonance linewidth rapidly broadens, providing evidence of antiferromagnetic spin fluctuations. This likely indicates that, analogously to manganites, the long-range antiferromagnetic order in GdBaCo $_{2}$ O $_{5.0}$ sets in at ≈ $T_{CO}$ . Pair distribution function analysis of diffraction data revealed signatures of structural inhomogeneities at low temperature. By comparing the average and local bond valences, we found that above $T_{CO}$ the local structure is consistent with a fully random occupation of Co $^{2 +}$ and Co $^{3 +}$ in a 1:1 ratio and with a complete charge ordering below $T_{CO}$ . Below $T$ ≈ 100 K the charge localization is partially melted at the local scale, suggesting a reentrant behavior of charge ordering. This result is supported by the weakening of superstructure reflections and the temperature evolution of electron paramagnetic resonance linewidth that is consistent with paramagnetic reentrant behavior reported in the GdBaCo $_{2}$ O $_{5.5}$ parent compound.
Cited by 16
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Cited by 17
- 24 November 2012
- Published by Springer Nature in Journal of Nanoparticle Research
Time effects on the stability of the induced defects in TiO2 nanoparticles doped by different nitrogen sources
by F. Spadavecchia, S. Ardizzone, G. Cappelletti, C. Oliva, S. Cappelli
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- 24 November 2012
- Published by Springer Nature in Journal of Nanoparticle Research
Time effects on the stability of the induced defects in TiO2 nanoparticles doped by different nitrogen sources
by F. Spadavecchia, S. Ardizzone, G. Cappelletti, C. Oliva, S. Cappelli
Cited by 17
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Cited by 16
- 16 July 2012
- Published by American Chemical Society (ACS) in Inorganic Chemistry
Electron Paramagnetic Resonance Analysis of La_1–xM_xMnO_3+δ (M = Ce, Sr) Perovskite-Like Nanostructured Catalysts
by Cesare Oliva, Mattia Allieta, Marco Scavini, Cesare Biffi, Ilenia Rossetti, Lucio Forni
The physical-chemical properties of some nanostructured perovskite-like catalysts of general formula La_1–xM_xMnO_3+δ (M = Ce, Sr) have been investigated, in particular by using the electron paramagnetic resonance (EPR) technique. We show that the interplay between the -O-Mn³⁺-O-Mn⁴⁺-O- electron double-exchange and the electron mobility is strictly dependent on the dopant nature and the annealing conditions in air. A relationship between the observed properties of these samples and their activity in the methane flameless catalytic combustion is proposed.
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- 16 July 2012
- Published by American Chemical Society (ACS) in Inorganic Chemistry
Electron Paramagnetic Resonance Analysis of La_1–xM_xMnO_3+δ (M = Ce, Sr) Perovskite-Like Nanostructured Catalysts
by Cesare Oliva, Mattia Allieta, Marco Scavini, Cesare Biffi, Ilenia Rossetti, Lucio Forni
The physical-chemical properties of some nanostructured perovskite-like catalysts of general formula La_1–xM_xMnO_3+δ (M = Ce, Sr) have been investigated, in particular by using the electron paramagnetic resonance (EPR) technique. We show that the interplay between the -O-Mn³⁺-O-Mn⁴⁺-O- electron double-exchange and the electron mobility is strictly dependent on the dopant nature and the annealing conditions in air. A relationship between the observed properties of these samples and their activity in the methane flameless catalytic combustion is proposed.
Cited by 16
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Cited by 8
- 27 December 2011
- Published by American Physical Society (APS) in Physical Review B
Spin-lattice interaction in the insulator-to-metal transition of GdBaCo2O5+δ
by Mattia Allieta, Cesare Oliva, Marco Scavini, Serena Cappelli, Ekaterina Pomjakushina, Valerio Scagnoli
We use electron paramagnetic resonance spectroscopy (EPR) and synchrotron radiation x-ray powder diffraction to study the temperature-induced insulator-to-metal transition (IMT) for GdBaCo $_{2}$ O $_{5 + δ}$ samples in the δ range 0.54(1) ⩽ δ ⩽ 0.63(1). The EPR linewidth markedly changes across IMT and its temperature evolution can be explained considering spin state transition involving Co ions. The temperature dependences of the EPR linewidth and of the $a$ lattice parameter fairly overlap each other suggesting spin-lattice interaction along the same crystallographic direction of the reported Ising-like spin anisotropy [A. A. Taskin et al., Phys. Rev. Lett. 90, 227201 (2003)]. A possible mechanism describing the interplay between this strong spin-lattice interaction and IMT is proposed. DOI: http://dx.doi.org/10.1103/PhysRevB.84.235144 ©2011 American Physical Society
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- 27 December 2011
- Published by American Physical Society (APS) in Physical Review B
Spin-lattice interaction in the insulator-to-metal transition of GdBaCo2O5+δ
by Mattia Allieta, Cesare Oliva, Marco Scavini, Serena Cappelli, Ekaterina Pomjakushina, Valerio Scagnoli
We use electron paramagnetic resonance spectroscopy (EPR) and synchrotron radiation x-ray powder diffraction to study the temperature-induced insulator-to-metal transition (IMT) for GdBaCo $_{2}$ O $_{5 + δ}$ samples in the δ range 0.54(1) ⩽ δ ⩽ 0.63(1). The EPR linewidth markedly changes across IMT and its temperature evolution can be explained considering spin state transition involving Co ions. The temperature dependences of the EPR linewidth and of the $a$ lattice parameter fairly overlap each other suggesting spin-lattice interaction along the same crystallographic direction of the reported Ising-like spin anisotropy [A. A. Taskin et al., Phys. Rev. Lett. 90, 227201 (2003)]. A possible mechanism describing the interplay between this strong spin-lattice interaction and IMT is proposed. DOI: http://dx.doi.org/10.1103/PhysRevB.84.235144 ©2011 American Physical Society
Cited by 8
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Cited by 43
- 1 March 2011
- Published by Elsevier in Catalysis Today
Photocatalytic removal of ethanol and acetaldehyde by N-promoted TiO2 films: The role of the different nitrogen sources
by D. Meroni, S. Ardizzone, G. Cappelletti, C. Oliva, M. Ceotto, D. Poelman, H. Poelman
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- 1 March 2011
- Published by Elsevier in Catalysis Today
Photocatalytic removal of ethanol and acetaldehyde by N-promoted TiO2 films: The role of the different nitrogen sources
by D. Meroni, S. Ardizzone, G. Cappelletti, C. Oliva, M. Ceotto, D. Poelman, H. Poelman
Cited by 43

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