| 1. |
- Hanifpour, Fatemeh, et al.
(författare)
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Operando quantification of ammonia produced from computationally-derived transition metal nitride electro-catalysts
- 2022
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Ingår i: Journal of Catalysis. - : Elsevier. - 0021-9517 .- 1090-2694. ; 413, s. 956-967
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Tidskriftsartikel (refereegranskat)abstract
- Electrochemical reduction of dinitrogen to ammonia is investigated in a micro-reactor flow-cell using thin films of VN, CrN, NbN and ZrN. Chronoamperometry loops are used for ammonia production analysis. Operando ammonia quantification is accomplished in a flow injection analyzer. Results show the effect of presence/absence of N-2(g) within both the electrochemical characterization and ammonia production for ZrN. However, no ammonia is detected from studies on CrN. VN and NbN are inactivated upon reacting their N atoms of the surface top layer(s). Results obtained from ammonia measurements, electrochemical impedance spectroscopy analysis, surface stability checks, and surface characterization using X-ray reflectivity, reveal certain trends indicating catalytic behavior for ZrN. However, the concentration of produced ammonia is below the detection limit of the methods devised to analyze the samples from isotope labeling experiments. The onset of ammonia production on ZrN appears to be in close agreement with that predicted previously by computational studies.
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| 2. |
- Holmlid, Leif, 1942, et al.
(författare)
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Laser-induced annihilation: Relativistic particles from ultra-dense hydrogen H(0)
- 2021
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Ingår i: High Energy Density Physics. - : Elsevier BV. - 1574-1818. ; 40
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Tidskriftsartikel (refereegranskat)abstract
- Particle annihilation means that nuclear particles annihilate each other (for example nucleons like a neutron and an anti-neutron) and generate showers of mesons (mainly kaons and pions) at high energy. The kaons decay via pions and muons to electrons, positrons, neutrinos and photons. The energy which can be extracted from the very fast particles is of the order of 50% of the total energy of the nucleon masses involved or 500 MeV per mass unit. Several reports have been published recently on the meson showers ejected by pulsed-laser impact on ultra-dense hydrogen H(0). Since the particle velocities often are relativistic at >100 MeVu 1 it is clear that a much more efficient nuclear process is responsible than in a normal hydrogen isotope fusion process (which can give only 3 and 15 MeV per mass unit out). The first experiment showing heat production above break-even in a laser-induced nuclear process in H(0) was published in AIP Avances as early as 2015. Here, we use a standard method for relativistic particle detection to show that the particles ejected by the laser pulse from D(0) are charged (thus not photons), and in fact positive, and that the signals decay with the characteristic decay times of kaons and pions with uncertainty < 1%. Using the measured kinetic energies of the mesons gives exact energy conservation. We conclude that annihilation of nucleons in H(0) is observed. This may have profound effects on future energy production, since the efficiency of the fuel in annihilation is roughly a factor of 100 higher than in a nuclear fusion process. Ordinary hydrogen (protium and deuterium) can be used as fuel instead of radioactive tritium. This means that energy is generated at low cost and with very little harmful radiation both for terrestrial and space applications (Acta Astronautica 2020).
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| 3. |
- Petruhins, Andrejs, et al.
(författare)
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Mn3GaC inverse perovskite thin films by magnetron sputtering from elemental targets
- 2020
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Ingår i: Materials Research Express. - : IOP PUBLISHING LTD. - 2053-1591. ; 7:10
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Tidskriftsartikel (refereegranskat)abstract
- We have deposited epitaxial thin films of the inverse perovskite Mn3GaC using magnetron sputtering from elemental targets. Two substrates were used, MgO (111) and (100), resulting in corresponding orientation of the Mn3GaC thin films. Both samples displayed magnetic properties consistent with an AFM to FM transition at similar to 170 K and a Curie temperature around 265 K, evaluated with vibrating sample magnetometry (in-plane measurements). These two ground states are further supported by first principles calculations. Based on that the two orientations of Mn3GaC display very similar magnetic properties, it can be concluded that shape anisotropy dominates over the materials easy axis.
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