| 1. |
- Bousquet, Jean, et al.
(författare)
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ARIA digital anamorphosis : Digital transformation of health and care in airway diseases from research to practice
- 2021
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Ingår i: Allergy. European Journal of Allergy and Clinical Immunology. - : John Wiley & Sons. - 0105-4538 .- 1398-9995. ; 76:1, s. 168-190
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Forskningsöversikt (refereegranskat)abstract
- Digital anamorphosis is used to define a distorted image of health and care that may be viewed correctly using digital tools and strategies. MASK digital anamorphosis represents the process used by MASK to develop the digital transformation of health and care in rhinitis. It strengthens the ARIA change management strategy in the prevention and management of airway disease. The MASK strategy is based on validated digital tools. Using the MASK digital tool and the CARAT online enhanced clinical framework, solutions for practical steps of digital enhancement of care are proposed.
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| 2. |
- Anil Kumar, Puri, et al.
(författare)
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Magnetic polarons and spin-glass behavior in insulating La1-xSrxCoO3 (x = 0.125 and 0.15)
- 2020
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Ingår i: Physical Review Research. - : AMER PHYSICAL SOC. - 2643-1564. ; 2:4
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Tidskriftsartikel (refereegranskat)abstract
- The evolution of magnetic polarons in Sr doped LaCoO3 (La1-xSrxCoO3) single crystal and polycrystalline samples are investigated by employing dc and ac magnetic measurement and small angle neutron scattering (SANS) techniques. The effect of magnetic field and temperature on magnetic polarons is experimentally studied for La0.875Sr0.125CoO3 and La0.85Sr0.15CoO3 compounds that belong to the spin glass insulating regime of the broader compositional phase diagram of this system. Langevin analyses of the isothermal magnetization curves in the notional paramagnetic regime prove the existence of magnetic polarons with large moments. The dc field superimposed ac susceptibility data and the analysis of the glassy dynamics prove that the size of polarons in 15% Sr doped crystal increase as the field is increased while the field effect is not visible in the 12.5% Sr doped crystal. A polycrystalline sample of La0.85Sr0.15CoO3 is analyzed by SANS experiments, which confirm nonzero correlation length at temperatures far above the macroscopic ordering temperature and hence the presence of magnetic polarons.
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| 3. |
- Baričić, Miran, et al.
(författare)
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Chemical engineering of cationic distribution in spinel ferrite nanoparticles : the effect on the magnetic properties
- 2024
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Ingår i: Physical Chemistry, Chemical Physics - PCCP. - : Royal Society of Chemistry. - 1463-9076 .- 1463-9084. ; 26:7, s. 6325-6334
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Tidskriftsartikel (refereegranskat)abstract
- A set of ∼9 nm CoFe2O4 nanoparticles substituted with Zn2+ and Ni2+ was prepared by thermal decomposition of metallic acetylacetonate precursors to correlate the effects of replacement of Co2+ with the resulting magnetic properties. Due to the distinct selectivity of these cations for the spinel ferrite crystal sites, we show that it is possible to tailor the magnetic anisotropy, saturation magnetization, and interparticle interactions of the nanoparticles during the synthesis stage. This approach unlocks new possibilities for enhancing the performance of spinel ferrite nanoparticles in specific applications. Particularly, our study shows that the replacement of Co2+ by 48% of Zn2+ ions led to an increase in saturation magnetization of approximately 40% from ∼103 A m2 kg−1 to ∼143 A m2 kg−1, whereas the addition of Ni2+ at a similar percentage led to an ∼30% decrease in saturation magnetization to 68–72 A m2 kg−1. The results of calculations based on the two-sublattice Néel model of magnetization match the experimental findings, demonstrating the model's effectiveness in the strategic design of spinel ferrite nanoparticles with targeted magnetic properties through doping/inversion degree engineering.
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| 4. |
- Basini, M., et al.
(författare)
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Low-temperature anomalies in muon spin relaxation of solid and hollow gamma-Fe2O3 nanoparticles : A pathway to detect unusual local spin dynamics
- 2020
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Ingår i: Physical Review B. - : American Physical Society (APS). - 2469-9950 .- 2469-9969. ; 102:19
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Tidskriftsartikel (refereegranskat)abstract
- By means of muon spin relaxation measurements we unraveled the temperature spin dynamics in monodisperse maghemite spherical nanoparticles with different surface to volume ratio, in two samples with a full core (diameter D similar to 4 and D similar to 5 nm) and one with a hollow core (external diameter D similar to 7.4 nm). The behavior of the muon longitudinal relaxation rates as a function of temperature allowed us to identify two distinct spin dynamics. The first is well witnessed by the presence of a characteristic peak for all the samples around the so-called muon blocking temperature T-B(mu+). A Bloembergen-Purcell-Pound (BPP)-like model reproduces the experimental data around the peak and at higher temperatures (20 < T < 100 K) by assuming the Neel reversal time of the magnetization as the dominating correlation time. An additional dynamic emerges in the samples with higher surface to volume ratio, namely, full 4 nm and hollow samples. This is witnessed by a shoulder of the main peak for T < 20 K at low longitudinal field (mu H-0 approximate to 15 mT), followed by an abrupt increase of the relaxation rate at T < 10 K, which is more evident for the hollow sample. These unusual anomalies of the longitudinal relaxation rate for T < T-B(mu+) are suggested to be due to the surface spins' dynamical behavior. Furthermore, for weak applied longitudinal magnetic field (mu H-0 approximate to 15 mT) and T < T-B(mu+) we observed damped coherent oscillations of the muon asymmetry, which are a signature of a quasistatic local field at the muon site as probed by muons implanted in the inner magnetic core of the nanoparticles. The muon spin relaxation technique turns out to be very successful to study the magnetic behavior of maghemite nanoparticles and to detect their unusual local spin dynamics in low magnetic field conditions.
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| 5. |
- Cedervall, Johan, et al.
(författare)
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Magnetic property changes of NdGa upon hydrogen absorption
- 2024
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Ingår i: Physical Review B. - : American Physical Society. - 2469-9950 .- 2469-9969. ; 109:13
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Tidskriftsartikel (refereegranskat)abstract
- Rare earth monogallide (REGa) Zintl phases are attractive for their properties in hydrogen storage and magnetic cooling. However, the magnetic effects upon hydrogen additions in REGa are not well understood. This study aims to explore the magnetic effects in REGaHx using SQUID magnetometry and neutron powder diffraction. To avoid challenges due to absorption and high incoherent scattering in the neutron diffraction experiments, the compound NdGaDx (x = 0, 0.9, or 1.6) was chosen for examination. It was found that NdGa exhibits two ferromagnetic structures below the Curie temperature of 42 K. Just below 42 K the magnetic moments are oriented along the crystallographic c axis, and at 20 K a spin reorientation occurs where the moments turn similar to 30 degrees toward the a axis. Upon partial deuteration (x = 0.9), the magnetization decreases and two magnetic phases are observed, one intermediate incommensurate phase, and one canted ferromagnetic phase with the net magnetization aligning along the b axis. For the full deuteride (x = 1.6) only one incommensurate magnetic phase is observed at low temperatures. Magnetometry also reveals that there are no isotope effects when absorbing H or D. The absorption of H or D changes the Nd-Nd distances as well as the electronic structure, which results in a drastic change in the magnetic properties as compared to NdGa.
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| 6. |
- Cedervall, Johan, et al.
(författare)
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Phase stability and structural transitions in compositionally complex LnMO 3 perovskites
- 2021
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Ingår i: Journal of Solid State Chemistry. - : Elsevier BV. - 0022-4596 .- 1095-726X. ; 300
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Tidskriftsartikel (refereegranskat)abstract
- Entropy stabilised materials have possibilities for tailoring functionalities to overcome challenges in materials science. The concept of configurational entropy can also be applied to metal oxides, but it is unclear whether these could be considered as solid solutions in the case of perovskite-structured oxides and if the configurational entropy plays a stabilising role. In this study, compositionally complex perovskite oxides, LnMO3 (Ln = La, Nd, Sm, Ca and Sr, M = Ti, Cr, Mn, Fe, Co, Ni, and Cu), are investigated for their phase stability and magnetic behaviour. Phase-pure samples were synthesised, and the room temperature structures were found to crystallise in either Pnma or R3¯c space groups, depending on the composition and the resulting tolerance factor, while the structural transition temperatures correlate with the pseudo cubic unit cell volume. The techniques used included diffraction with X-rays and neutrons, both ex- and in-situ, X-ray photoelectron spectroscopy, magnetometry as well as electron microscopy. Neutron diffraction studies on one sample reveal that no oxygen vacancies are found in the structure and that the magnetic properties are ferrimagnetic-like with magnetic moments mainly coupled antiferromagnetically along the crystallographic c-direction. X-ray photoelectron spectroscopy gave indications of the oxidation states of the constituting ions where several mixed oxidation states are observed in these valence-compensated perovskites.
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| 7. |
- Denoel, Fernand
(författare)
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Electronic and magnetic properties of Tsai quasicrystals and their approximants under pressure
- 2022
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Quasicrystals constitute a special category of crystals exhibiting long-range order without periodicity. This strange feature allows them to exhibit rotational symmetries prohibited in regular crystals, such as 5-, 8-, 10- or 12-fold symmetry. Amongst them, icosahedral quasicrystals are the only type that is aperiodic along all 3 dimensions. The present work will focus on Tsai-Type quasicrystals and their approximants, which are the most studied type of icosahedral quasicrystals. We will introduce how they can be generated froma hyperspace perspective, their exotic structure and how it relates to their physical properties. Pressure is a key parameter which can be used to alter the condensed matter properties of a material. By reducing the size of samples and using diamond anvil cells, it is possible to obtain the highest experimentally achievable pressures and collect informations such as magnetization, electrical resistivity or Raman signal. This work will introduce the specialized diamond anvil cells we used to investigate electron transport and magnetization under pressure, explain in details how to circumvent the most common difficulties arising with high pressure setups. and describe how high pressure affects Tsai quasicrystals and approximants in terms of structure and magnetic properties.
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| 8. |
- Denoel, Fernand, et al.
(författare)
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Eu Doping in the GdCd7.88 Quasicrystal and Its Approximant Crystal GdCd6
- 2024
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Ingår i: Inorganic Chemistry. - : American Chemical Society (ACS). - 0020-1669 .- 1520-510X. ; 63:11, s. 5040-5051
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Tidskriftsartikel (refereegranskat)abstract
- The effect of Eu doping in the Tsai quasicrystal (QC) GdCd7.88 and its periodic 1/1 approximant crystal (AC) GdCd6 are investigated. This represents the first synthesis of Eu-containing stable QC samples, where three samples with the final composition Gd1-xEuxCd7.6±α at Eu doping concentrations x = 0.06, 0.13, and 0.19 are obtained (α ∼ 0.2). They are compared to two 1/1 ACs with compositions Gd1-xEuxCd6 (x = 0.12, 0.16). In addition, a new type of 1/1 AC, differing only by the inclusion of extra Cd sites unique to the Eu4Cd25 1/1 AC, has been discovered and synthesized for the concentrations Gd1-xEuxCd6+δ (x = 0.25, 0.33, 0.45, 0.69, 0.73, and 0 < δ ≤ 0.085). Due to the preferred cube morphology of its single grains, we refer to them as c-type 1/1 ACs and to the conventional standard ones as s-type. In both QCs and s-type ACs, the Eu content appears to saturate at a concentration of similar to 20%. On the other hand, any Gd| Eu ratio is allowed in the c-type ACs, varying continuously between GdCd6 and Eu4Cd25. We describe and contrast the changes in composition, atomic structure, specific heat, and magnetic properties induced by Eu doping in the quasicrystalline phase and the s-type and c-type 1/1 ACs. By comparing our results to the literature data, we propose that the occupancy of the extra Cd sites can be used to predict the stability of Tsai-type quasicrystalline phases.
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| 9. |
- Denoel, Fernand
(författare)
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Frustrated magnetism in icosahedral structures : The influence of order-disorder in quasicrystals and approximant crystals
- 2024
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This work will begin with an introduction to quasicrystals (QCs) and their structure, defining the unit cell-equivalent for icosahedral quasiperiodicity: a 3D tiling based on the golden ratio and aperiodic in all three dimensions. We briefly present the cut-and-project method used to generate QCs from a higher dimension hypercrystal, and how to build the 3D Penrose tilings, composed of the two golden rhombohedra. We introduce the atomic elementary units used to understand Tsai-type icosahedral QCs and their related approximant crystals (ACs). Approximants are conventional periodic crystals with local atomic environments very similar to their QC counterparts. Two methods for synthesis of Tsai-type QCs and approximants are introduced, the self-flux method as well as a rapid quench method. We describe briefly the differences between the two methods and aspect about phase stability for QCs and ACs obtained in binary and ternary systems. Various types of structural modulations can be induced in ACs which are absent from QCs. We present a new criterion discovered during the doctoral studies, which links the structure of existing ACs to the existence of stable QC counterparts. Basic concepts of magnetism relevant to Tsai systems are then introduced, with a description of the 4f shell magnetism in lanthanide elements, how it differs from transition metal magnetism, with localized (and relatively large) magnetic moments. In intermetallic systems such as Tsai-type QCs and ACs, the main type of magnetic interaction is of RKKY type. We link their structure to the magnetic behavior and phase transition that can occur in frustrated systems: spin glass, reentrant spin glass, spin ice, etc. and how they can be related to various Tsai systems.
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| 10. |
- Eder, Felix, et al.
(författare)
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The Cobalt(II) Oxidotellurate(IV) Hydroxides Co-2(TeO3)(OH)2 and Co15(TeO3)14(OH)2
- 2023
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Ingår i: Crystals. - : MDPI. - 2073-4352. ; 13:2
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Tidskriftsartikel (refereegranskat)abstract
- Previously unknown Co-2(TeO3)(OH)(2) and Co-15(TeO3)(14)(OH)(2) were obtained under mild hydrothermal reaction conditions (210 degrees C, autogenous pressure) from alkaline solutions. Their crystal structures were determined from single-crystal X-ray diffraction data. Co-2(TeO3)(OH)(2) (Z = 2, P1 over bar , a = 5.8898(5), b = 5.9508(5), c = 6.8168(5) & ANGS;, alpha = 101.539(2), beta = 100.036(2), gamma = 104.347(2)& DEG;, 2120 independent reflections, 79 parameters, R[F-2 > 2 sigma(F-2)] = 0.017) crystallizes in a unique structure comprised of undulating (2)(& PROP;)[Co-2(OH)(6/3)O3/3O2/2O1/1](4-) layers. Adjacent layers are linked by Te-IV atoms along the [001] stacking direction. Co-2(TeO3)(OH)(2) is stable up to 450 & DEG;C and decomposes under the release of water into Co6Te5O16 and CoO. Magnetic measurements of Co-2(TeO3)(OH)(2) showed antiferromagnetic ordering at & AP; 70 K. The crystal structure of Co-15(TeO3)(14)(OH)(2) (Z = 3, R3 over bar , a = 11.6453(2), c = 27.3540(5) & ANGS;, 3476 independent reflections, 112 parameters, R[F-2 > 2 sigma(F-2)] = 0.026) is isotypic with Co-15(TeO3)(14)F-2. A quantitative structural comparison revealed that the main structural difference between the two phases is connected with the replacement of F by OH, whereas the remaining part of the three-periodic network defined by [CoO6], [CoO5(OH)], [CoO5] and [TeO3] polyhedra is nearly unaffected. Consequently, the magnetic properties of the two phases are similar, namely being antiferromagnetic at low temperatures.
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