| 1. |
- Baron, P., et al.
(författare)
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Potential for the measurement of mesosphere and lower thermosphere (MLT) wind, temperature, density and geomagnetic field with Superconducting Submillimeter-Wave Limb-Emission Sounder 2 (SMILES-2)
- 2020
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Ingår i: Atmospheric Measurement Techniques. - : Copernicus GmbH. - 1867-1381 .- 1867-8548. ; 13:1, s. 219-237
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Tidskriftsartikel (refereegranskat)abstract
- Submillimeter-Wave Limb-Emission Sounder 2 (SMILES-2) is a satellite mission proposed in Japan to probe the middle and upper atmosphere (20-160 km). The main instrument is composed of 4K cooled radiometers operating near 0.7 and 2 THz. It could measure the diurnal changes of the horizontal wind above 30 km, temperature above 20 km, ground-state atomic oxygen above 90 km and atmospheric density near the mesopause, as well as abundance of about 15 chemical species. In this study we have conducted simulations to assess the wind, temperature and density retrieval performance in the mesosphere and lower thermosphere (60- 110 km) using the radiometer at 760 GHz. It contains lines of water vapor (H2O), molecular oxygen (O2) and nitric oxide (NO) that are the strongest signals measured with SMILES-2 at these altitudes. The Zeeman effect on the O2 line due to the geomagnetic field (B) is considered; otherwise, the retrieval errors would be underestimated by a factor of 2 above 90 km. The optimal configuration for the radiometer's polarization is found to be vertical linear. Considering a retrieval vertical resolution of 2.5 km, the line-of-sight wind is retrieved with a precision of 2-5ms-1 up to 90 km and 30ms-1 at 110 km. Temperature and atmospheric density are retrieved with a precision better than 5K and 7% up to 90 km (30K and 20% at 110 km). Errors induced by uncertainties on the vector B are mitigated by retrieving it. The retrieval of B is described as a side-product of the mission. At high latitudes, precisions of 30-100 nT on the vertical component and 100-300 nT on the horizontal one could be obtained at 85 and 105 km (vertical resolution of 20 km). SMILES-2 could therefore provide the first measurements of B close to the electrojets' altitude, and the precision is enough to measure variations induced by solar storms in the auroral regions.
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| 2. |
- Nocerino, Elisabetta, et al.
(författare)
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Na-ion Dynamics in the Solid Solution NaxCa1-xCr2O4 Studied by Muon Spin Rotation and Neutron Diffraction
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- In this work we present systematic set of measurements carried out by muon spin rotation/relaxation (μ+SR) and neutron powder diffraction (NPD) on the solid solution NaxCa1−xCr2O4. This study investigates Na-ion dynamics in the quasi-1D (Q1D) diffusion channels created by the honeycomb-like arrangement of CrO6 octahedra, in the presence of defects introduced by Ca doping. With increasing Ca content, the size of the diffusion channels is enlarged, however, this effect does not enhance the Na ion mobility. Instead the overall diffusivity is hampered by the local defects and the Na hopping probability is lowered. The diffusion mechanism in NaxCa1−xCr2O4 was found to be interstitial and the activation energy as well as diffusion coefficient were determined for all the members of the solid solution.
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| 3. |
- Nocerino, Elisabetta, et al.
(författare)
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Na-ion dynamics in the solid solution NaxCa1-xCr2O4 studied by muon spin rotation and neutron diffraction
- 2024
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Ingår i: Sustainable Energy & Fuels. - : Royal Society of Chemistry. - 2398-4902. ; 8:7, s. 1424-1437
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Tidskriftsartikel (refereegranskat)abstract
- In this work we present a systematic set of measurements carried out by muon spin rotation/relaxation (μ+SR) and neutron powder diffraction (NPD) on the solid solution NaxCa1−xCr2O4. This study investigates Na-ion dynamics in the quasi-1D (Q1D) diffusion channels created by the honeycomb-like arrangement of CrO6 octahedra, in the presence of defects introduced by Ca substitution. With increasing Ca content, the size of the diffusion channels is enlarged; however, this effect does not enhance the Na ion mobility. Instead the overall diffusivity is hampered by the local defects and the Na hopping probability is lowered. The diffusion mechanism in NaxCa1−xCr2O4 is proposed to be interstitial and the activation energy as well as diffusion coefficient are determined for all the members of the solid solution.
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| 4. |
- Nocerino, Elisabetta, et al.
(författare)
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Na-ion dynamics in the solid solution NaxCa1−xCr2O4 studied by muon spin rotation and neutron diffraction
- 2024
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Ingår i: Sustainable Energy & Fuels. - : ROYAL SOC CHEMISTRY. - 2398-4902. ; 8:7
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Tidskriftsartikel (refereegranskat)abstract
- In this work we present a systematic set of measurements carried out by muon spin rotation/relaxation (mu+SR) and neutron powder diffraction (NPD) on the solid solution NaxCa1-xCr2O4. This study investigates Na-ion dynamics in the quasi-1D (Q1D) diffusion channels created by the honeycomb-like arrangement of CrO6 octahedra, in the presence of defects introduced by Ca substitution. With increasing Ca content, the size of the diffusion channels is enlarged; however, this effect does not enhance the Na ion mobility. Instead the overall diffusivity is hampered by the local defects and the Na hopping probability is lowered. The diffusion mechanism in NaxCa1-xCr2O4 is proposed to be interstitial and the activation energy as well as diffusion coefficient are determined for all the members of the solid solution.
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| 5. |
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| 6. |
- Nocerino, E., et al.
(författare)
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Unusually large magnetic moment and tricritical behavior of the CMR compound NaCr 2 O 4 revealed with high resolution neutron diffraction and μ + SR
- 2023
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Ingår i: JPhys Materials. - 2515-7639. ; 6:3
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Tidskriftsartikel (refereegranskat)abstract
- The mixed valence Cr3+/Cr4+ compound NaCr2O4, hosts a plethora of unconventional electronic properties. In the present study, muon spin rotation/relaxation ( μ + SR) and high-resolution time-of-flight neutron powder diffraction measurements were carried out on high-quality samples to clarify the complex magnetic ground state of this unique material. We identified a commensurate canted antiferromagnetic order (C-AFM) with a canting angle of the Cr spin axial vector equal to θ c = ( 8.8 ± 0.5 ) ∘ , and an estimated Cr moment μ C r C ∼ ( 4.30 ± 0.01 ) μ B . Such an unusually large value of μ C r C is compatible with the existence of high-spin Cr sites created by the presence of an unconventional negative charge transfer state in NaCr2O4. In addition to the C-AFM structure, a novel magnetic supercell was also revealed. Such supercell display an incommensurate (IC)-AFM propagation vector (0 0 1 2 − δ ), having a Cr moment μ C r I C = ( 2.20 ± 0.03 ) μ B . It is suggested that the C-AFM and IC-AFM modulations have two different electronic origins, being due to itinerant and localized contributions to the magnetic moment respectively. Finally, the direct measurement of the magnetic order parameter for the C-AFM structure provided a value of the critical exponent β = 0.245 ≈ 1 4 , suggesting a non conventional critical behavior for the magnetic phase transition in NaCr2O4
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| 7. |
- Nocerino, Elisabetta, et al.
(författare)
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Unusually large magnetic moment and tricritical behavior of the CMR compound NaCr2O4 revealed with high resolution neutron diffraction and mu(+) SR
- 2023
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Ingår i: Journal of Physics. - : IOP Publishing. - 2515-7639. ; 6:3
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Tidskriftsartikel (refereegranskat)abstract
- The mixed valence Cr3+/Cr4+ compound NaCr2O4, hosts a plethora of unconventional electronic properties. In the present study, muon spin rotation/relaxation (mu(+) SR) and high-resolution time-of-flight neutron powder diffraction measurements were carried out on high-quality samples to clarify the complex magnetic ground state of this unique material. We identified a commensurate canted antiferromagnetic order (C-AFM) with a canting angle of the Cr spin axial vector equal to theta
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