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234 results on '"Benedetti, Alvise"'

4. Small-angle scattering behavior of thread-like and film-like systems

Author

Ciccariello, Salvino, Riello, Pietro, and Benedetti, Alvise

Subjects
Condensed Matter - Materials Science
Abstract

A film-like or a thread-like system is a system such that one of its constituting homogeneous phases has a constant thickness $\delta$ or a constant normal section of largest diameter $\delta$. The stick probability function of this phase, in the limit $\delta \to 0$, naturally leads to the definition of the correlation function (CF) of a surface or a curve. This CF fairly approximates the generating stick probability function in the range of distances larger than $\delta$. The surface and the curve CFs respectively behave as $1/r$ and $1/r^2$ as $r \to 0$. In the two cases, this result implies that small-angle scattering intensities of the relevant samples respectively behave as $1/q^2$ and $1/q$ in an intermediate range of the scattering vector $q$ and as $1/q^4$ in the outermost one. One reports the analytic expressions of the pre-factors of these behaviors. It may happen that a sample looks thread-like at large scale resolution and film-like at smaller one. The surface and the curve CFs have explicitly been evaluated for some simple geometrical shapes. Besides, it is also reported the algebraic expression of the circular cylinder CF in terms of two elliptic integral functions, and it is shown that the limits of this CF, as the height or the radius of the cylinder approaches to zero, coincide with the CF of a disk or a linear segment, respectively., Comment: 37 pages, 18 figures

Published
2015

6. Stabilizing cubic γ-Ga2O3:Cr3+ spinel nanocrystals by size confinement into mesoporous silica nanoreactor channels.

Author

Crozzolin, Michele, Belloni, Camilla, Xu, Jian, Nakanishi, Takayuki, Ueda, Jumpei, Tanabe, Setsuhisa, Dallo, Federico, Balliana, Eleonora, Saorin, Asia, Rizzolio, Flavio, Cristofori, Davide, Riello, Pietro, Benedetti, Alvise, and Back, Michele

Abstract

In recent years, Cr3+-activated phosphors have been attracting a lot of interest due to their unique optical features that can be exploited for applications ranging from lasers to optical thermometry, near-infrared (NIR) emitting phosphors for bioimaging and NIR-LEDs, to name a few. Despite the interesting optical properties shown by Cr3+-doped Ga2O3, investigations are limited only to β-Ga2O3 and α-Ga2O3 polymorphs. Using mesoporous silica particles with different pore sizes between 3 nm and 22 nm as nanoreactors, cubic γ-Ga2O3:Cr3+ spinel nanocrystals (NCs) are stabilized through confinement into the mesopores as confirmed by HR-TEM, XRPD and the photoluminescence spectral shape. A detailed spectroscopic investigation in the temperature range between 16 to 500 K allowed extrapolating the fundamental parameters in the framework of the Tanabe–Sugano diagram and comparing the values for Cr3+ in γ-Ga2O3 with the α- and β-phases. In addition, due to the confinement of the NCs into the silica structure, the phase transition to the β-phase, conventionally occurring at about 700 °C, is hindered up to 1000 °C, improving the stability of the γ-Ga2O3 phase. [ABSTRACT FROM AUTHOR]

Published
2024
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11. Thermochromic Narrow Band Gap Phosphors for Multimodal Optical Thermometry: The Case of Y³⁺-Stabilized beta-Bi₂O₃:Nd³⁺

Author

Back, Michele, Xu, Jian, Ueda, Jumpei, Benedetti, Alvise, and Tanabe, Setsuhisa

Subjects
Ions, Luminescence, Optical properties, Electrical conductivity, Materials
Abstract

The design and development of effective luminescent thermal sensors have been driving technological progress in many different fields ranging from catalysis to biology and microelectronics, to name a few. The ratiometric concept of using the ratio between two luminescent emissions of lanthanide-doped phosphors allows overcoming some limitations resulting from the single emission-based thermometers. A fundamental requirement for the development of effective luminescent thermometers relies on efficient luminescence output, which is not always accessible. Therefore, alternative methods to probe the temperature in a reliable and simple way are still a challenge. Despite the conventional limits of using narrow band gap materials as hosts for lanthanoid ions, a smart design allows for the development of unusual phosphors with appealing properties. By taking advantage of the narrow band gap of Bi₂O₃ polymorphs, here we demonstrate the potential of the tetragonal Y-stabilized β-Bi₂O₃:Y³⁺, Nd³⁺ system as a multimodal thermometer combining the conventional Boltzmann thermometry based on Nd³⁺ together with the thermochromism of the host. With the aim of testing this new concept, the temperature dependence of the reflectance spectra was investigated. Moreover, from the application point of view, the chromaticity variations of the material described by means of simple thermometric parameters such as the ratio a*/b* and the hue angle hab are demonstrated to be particularly promising and already implemented in software commonly used worldwide. The results suggest the potential of the strategy of combining narrow band gap semiconductors with lanthanoid ions to design reliable and multimodal thermal sensors, paving the way to a new family of thermochromic and luminescent thermal sensors.

Published
2022

22. Chirality in luminescent Cs3Cu2Br5 microcrystals produced via ligand-assisted reprecipitation.

Author

Branzi, Lorenzo, Kavanagh, Aoife, Back, Michele, Speghini, Adolfo, Gun'ko, Yurii K., and Benedetti, Alvise

Subjects
PRECIPITATION (Chemistry), CHIRALITY, OPTICAL properties, COPPER, CESIUM compounds
Abstract

Herein we report new chiral luminescent Cs3Cu2Br5 needle-like microcrystals and the analysis of their optical properties and the effect of the ligand structure on the transfer of chirality. [ABSTRACT FROM AUTHOR]

Published
2023
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26. Modification of Amorphous Mesoporous Zirconia Nanoparticles with Bisphosphonic Acids: A Straightforward Approach for Tailoring the Surface Properties of the Nanoparticles

Author

Hossain, Khohinur, primary, Florean, Luca, additional, Del Tedesco, Anna, additional, Cattaruzza, Elti, additional, Geppi, Marco, additional, Borsacchi, Silvia, additional, Canton, Patrizia, additional, Benedetti, Alvise, additional, Riello, Pietro, additional, and Scarso, Alessandro, additional

Published
2021
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27. ZnSnO 3 or Zn 2 SnO 4 /SnO 2 Hierarchical Material? Insight into the Formation of ZnSn(OH) 6 Derived Oxides.

Author

Redolfi-Bristol, Davide, Branzi, Lorenzo, Back, Michele, Riello, Pietro, Speghini, Adolfo, Pinna, Nicola, and Benedetti, Alvise

Subjects
X-ray powder diffraction, PIEZOELECTRIC materials, ENERGY harvesting, OXIDES, PIEZOELECTRICITY, SYNCHROTRON radiation
Abstract

Piezoelectric materials are a class of compounds that is gaining increasing interest in various applications such as energy harvesting. During the last decade, lead-free ZnSnO3 perovskite ceramic has gained attention among the scientific community thanks to its unique symmetry-dependent and spontaneous polarization properties such as piezoelectricity and ferroelectricity. Nevertheless, only a few studies successfully prepared pure ZnSnO3, while most seem to mislead the product for its hydroxide precursor (ZnSn(OH)6) or a mixture of Zn2SnO4 and SnO2. In our work, we investigated the conversion of ZnSn(OH)6 at different temperatures (500, 600, 700, 750 and 800 °C) by X-ray powder diffraction analysis, and in-situ using synchrotron radiation up to 950 °C under ambient atmosphere and in a vacuum, to reproduce conventional reaction conditions. SEM and TEM have been used to understand the evolution of the particle shape and surface structure before and after the thermal treatments. Our results show the instability of the ZnSn(OH)6 phase, which converts into an amorphous structure at low temperature. Above 750 °C, the material segregates into Zn2SnO4 and SnO2, supporting the hypothesis that the thermal treatment of the hydroxide phase under typical conditions results in the formation of an oxide mixture rather than the phase pure ZnSnO3. [ABSTRACT FROM AUTHOR]

Published
2022
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29. Genotoxicity and Immunotoxicity of Titanium Dioxide-Embedded Mesoporous Silica Nanoparticles (TiO2@MSN) in Primary Peripheral Human Blood Mononuclear Cells (PBMC)

Author

Di Giampaolo, Luca, primary, Zaccariello, Gloria, additional, Benedetti, Alvise, additional, Vecchiotti, Giulia, additional, Caposano, Francesca, additional, Sabbioni, Enrico, additional, Groppi, Flavia, additional, Manenti, Simone, additional, Niu, Qiao, additional, Poma, Anna Maria Giuseppina, additional, Di Gioacchino, Mario, additional, and Petrarca, Claudia, additional

Published
2021
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32. Confined-Melting-Assisted Synthesis of Bismuth Silicate Glass-Ceramic Nanoparticles: Formation and Optical Thermometry Investigation

Author

Back, Michele, primary, Casagrande, Elisa, additional, Trave, Enrico, additional, Cristofori, Davide, additional, Ambrosi, Emmanuele, additional, Dallo, Federico, additional, Roman, Marco, additional, Ueda, Jumpei, additional, Xu, Jian, additional, Tanabe, Setsuhisa, additional, Benedetti, Alvise, additional, and Riello, Pietro, additional

Published
2020
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37. Precursor-Dependent Photocatalytic Activity of Carbon Dots

Author

Emanuele, Amadio, primary, Cailotto, Simone, additional, Campalani, Carlotta, additional, Branzi, Lorenzo, additional, Raviola, Carlotta, additional, Ravelli, Davide, additional, Cattaruzza, Elti, additional, Trave, Enrico, additional, Benedetti, Alvise, additional, Selva, Maurizio, additional, and Perosa, Alvise, additional

Published
2019
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39. Kit e Metodo per Biopulitura Enzimatica di Superfici

Author

Storaro, Loretta, Benedetti, Alvise, Riello, Pietro, and Scarpa, Irene

Subjects
Biopulitura, enzimi, superfici, Settore CHIM/03 - Chimica Generale e Inorganica, enzimi, Biopulitura, superfici, Settore CHIM/02 - Chimica Fisica
Published
2018

45. High-temperature compressive creep of novel fine-grained orthorhombic ZrO2 ceramics stabilized with 12 mol% Ta doping

Author

Junta de Andalucía, European Commission, Junta de Extremadura, Ministerio de Economía y Competitividad (España), Sponchia, Gabriele, Moshtaghioun, Bibi Malmal, Riello, Prieto, Benedetti, Alvise, Gómez-García, D., Domínguez-Rodríguez, Domingo, Ortiz, Ángel L., Junta de Andalucía, European Commission, Junta de Extremadura, Ministerio de Economía y Competitividad (España), Sponchia, Gabriele, Moshtaghioun, Bibi Malmal, Riello, Prieto, Benedetti, Alvise, Gómez-García, D., Domínguez-Rodríguez, Domingo, and Ortiz, Ángel L.

Abstract

A novel fine-grained orthorhombic ZrO2 ceramic stabilized with 12 mol% Ta doping was fabricated by spark-plasma sintering from home-made powders, and its high-temperature mechanical properties evaluated for the first time by compressive creep tests in both Ar and air. It was found that the high-temperature plasticity of the ceramic deformed in Ar, under which the Ta-doped orthorhombic ZrO2 is a black suboxide with abundant oxygen vacancies in its crystal structure, is controlled by grain boundary sliding (stress exponent ∼2, and activation energy ∼780–800 kJ/mol). However, the high-temperature plasticity of the ceramic deformed in air, under which the Ta-doped orthorhombic ZrO2 is a white oxide due to the elimination in situ of oxygen vacancies, is controlled by recovery creep (stress exponent ∼3, and activation energy ∼750 kJ/mol). It was also observed that black Ta-doped orthorhombic ZrO2 is more creep resistant than its white counterpart with the same grain size, and that the former deforms as the more conventional Y2O3-stabilized ZrO2 does.

Published
2018

46. Inorganic nanoparticles: Possible solution for different problems

Author

Benedetti, Alvise

Subjects
silica, bismuth, Nanopartículas, zirconia, mesoporous nanoparticles
Abstract

Formation and Controlled Growth of Bismuth Titanate Phases into Mesoporous Silica Nanoparticles: An Efficient Self-Sealing Nanosystem for UV Filtering in Cosmetic Formulation. Biocompatible tailored zirconia mesoporous nanoparticles with high surface area for theranostic applications. Structural and photophysical properties of rare-earth complexes encapsulated into surface modified mesoporous silica nanoparticles Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech.

Published
2017

48. Small angle scattering of a polydisperse system of interacting hard spheres: An analytical solution.

Author

Riello, Pietro and Benedetti, Alvise

Subjects
*LIQUIDS, *AUTOCORRELATION (Statistics)
Abstract

Examines the autocorrelation functions of liquids used for a more accurate analysis of the full small angle pattern from mono and polydisperse systems with interparticle interaction. Effects of polydispersity and density in close-packed systems; Numerical integrartion of the intensity of the Born-Gren kinetic theory for fluids.

Published
1997
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49. Ceramics of Ta-doping stabilized orthorhombic ZrO2 densified by spark plasma sintering and the effect of post-annealing in air

Author

Junta de Andalucía, Junta de Extremadura, European Commission, Ministerio de Economía y Competitividad (España), Sponchia, Gabriele, Moshtaghioun, Bibi Malmal, Benedetti, Alvise, Riello, Prieto, Gómez-García, D., Domínguez-Rodríguez, Arturo, Ortiz, Ángel L., Junta de Andalucía, Junta de Extremadura, European Commission, Ministerio de Economía y Competitividad (España), Sponchia, Gabriele, Moshtaghioun, Bibi Malmal, Benedetti, Alvise, Riello, Prieto, Gómez-García, D., Domínguez-Rodríguez, Arturo, and Ortiz, Ángel L.

Abstract

16 mol% Ta-doped ZrO powders were synthesized and densified by spark-plasma sintering (SPS) in vacuum, followed by post-SPS annealing in air, thus obtaining two ultrafine-grained ceramics consisting of Ta-doping stabilized orthorhombic ZrO. The as-SPSed ceramic is black because it is actually a suboxide essentially with reduced cations and abundant oxygen vacancies, whereas the post-annealed ceramic is white because it is an oxide without vacancies and with only partially reduced cations. Both ceramics are relatively hard and brittle, but the as-SPSed ceramic was slightly more so, attributable to crystallographic and microstructural differences. Implications of interest for the ceramics community are discussed.

Published
2017

50. Thermal evolution of carbon-supported Pd nanoparticles studied by time-resolved X-ray diffraction

Author

Canton, Patrizia, Meneghini, Carlo, Riello, Pietro, Balerna, Antonella, and Benedetti, Alvise

Subjects
Palladium -- Thermal properties, Palladium -- Research, Chemistry, Physical and theoretical -- Research, Carbon -- Research, Carbon -- Thermal properties, Chemicals, plastics and rubber industries
Abstract

Time-resolved X-ray diffraction measurements are performed in situ on a carbon-supported Pd particles (Pd/C) catalyst during two successive thermal treatments from 300 to 873 K. The structural and micro structural evolution of Pd phases on a Pd/C catalyst as a function of thermal treatment, in a wide temperature range, using the TR-XRD technique is investigated.

Published
2001

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