Structural changes through the first-order paramagnetic–antiferromagnetic phase transition of Dy3Ru4Al12 at 7K have been studied by means of X-ray diffraction and thermal expansion measurements. The ...compound crystallizes in a hexagonal crystal structure of Gd3Ru4Al12 type (P63/mmc space group), and no structural phase transition has been found in the temperature interval between 2.5 and 300K. Nevertheless, due to the spin-lattice coupling the crystal volume undergoes a small orthorhombic distortion of the order of 2×10−5 as the compound enters the antiferromagnetic state. We propose that the first-order phase transition is not driven by the structural changes but rather by the exchange interactions present in the system.
•Dy3Ru4Al12 displays a first-order phase transition at the Néel temperature, 7K.•No structural phase transition has been found between 2.5 and 300K.•However, the compound undergoes a small orthorhombic distortion of ~2×10−5 at 7K.•We propose that the first-order transition is driven by exchange interactions.
We discuss the main design concepts for fault-tolerant microprocessors, Instruction Set Architectures (ISA) of microprocessors for space applications and the achievable characteristics considering ...the KOMDIV microprocessors designed by SRISA. The trade-off between the fault-tolerance, performance and power consumption is considered for microprocessors designed using the silicon-on-insulator (SOI) and bulk CMOS technologies.
•Instruction Set Architectures used for space applications are reviewed and discussed.•The main fault-tolerance enhancement techniques are discussed .•The fault tolerance of KOMDIV microprocessors is discussed for the first time.•The trade-off between the fault-tolerance, performance and power is considered.•The characteristics of 1907VM01A4 and 1907VM044 are discussed as the example.
We report on x-ray magnetic circular dichroism experiments in pulsed fields up to 30 T to follow the rotations of individual magnetic moments through the field-induced phase transition in the ...ferrimagnet HoFe5Al7. Near the ground state, we observe simultaneous stepwise rotations of the Ho and Fe moments and explain them using a two-sublattice model for an anisotropic ferrimagnet with weak intersublattice exchange interactions. Near the compensation point, we find two phase transitions. The additional magnetization jump reflects the fact that the Ho moment is no longer rigid as the applied field acts against the intersublattice exchange field.
This paper proposes the criteria for estimating the operational condition of an induction motor, determining a degree of its degradation wear, and predicting a failure-free operation and the ...emergency failure instance based on the rundown parameters after the power supply voltage is disconnected. The results of studying the possibility of using the induction motor rundown regime for diagnosing the degradation changes during operation are presented. A probabilistic statistical analysis of reliability and accuracy of the predicted parameters was performed, and the calculation equations for estimating the levels of measurement and predictions errors are provided.
Complexes of palladium(II) with N-heterocyclic carbenes of the PEPPSI-type were synthesized by the reaction of PdCl
2
with 1-adamantyl-3-(R-methyl)-1
H
-imidazolium salts. These complexes were used ...as productive precatalysts for substituted thiophene and imidazole arylation by C—H-activation.
Iron is an essential nutrient involved in a variety of biological processes in the ocean, including photosynthesis, respiration and dinitrogen fixation. Atmospheric deposition of aerosols is ...recognized as the main source of iron for the surface ocean. In high nutrient, low chlorophyll areas, it is now clearly established that iron limits phytoplankton productivity but its biogeochemical role in low nutrient, low chlorophyll environments has been poorly studied. We investigated this question in the unexplored southeast Pacific, arguably the most oligotrophic area of the global ocean. Situated far from any continental aerosol source, the atmospheric iron flux to this province is amongst the lowest of the world ocean. Here we report that, despite low dissolved iron concentrations (~0.1 nmol l−1) across the whole gyre (3 stations located in the center and at the western and the eastern edges), primary productivity are only limited by iron availability at the border of the gyre, but not in the center. The seasonal stability of the gyre has apparently allowed for the development of populations acclimated to these extreme oligotrophic conditions. Moreover, despite clear evidence of nitrogen limitation in the central gyre, we were unable to measure dinitrogen fixation in our experiments, even after iron and/or phosphate additions, and cyanobacterial nif H gene abundances were extremely low compared to the North Pacific Gyre. The South Pacific gyre is therefore unique with respect to the physiological status of its phytoplankton populations.
Crystal structure and magnetism of UOsAl Andreev, A.V.; Daniš, S.; Šebek, J. ...
Journal of magnetism and magnetic materials,
04/2017, Volume:
428
Journal Article
Peer reviewed
Crystal structure, magnetization, and specific heat were studied on single crystal of uranium intermetallic compound UOsAl. It is a hexagonal Laves phase of MgZn2 type, space group P63/mmc, with ...lattice parameters a=536.4pm, c=845.3pm. Shortest inter-uranium distance 313pm (along the c-axis) is considerably smaller than the Hill limit (340pm). The compound is a weakly temperature-dependent paramagnet with magnetic susceptibility of ≈1.5*10−8m3mol−1 (at T=2K), which is slightly higher with magnetic field along the a-axis compared to the c-axis. The Sommerfeld coefficient of electronic specific heat has moderate value of γ=36mJmol−1K−2.
•Crystal structure and magnetic properties were studied on single crystal of UOsAl with hexagonal structure of MgZn2 type.•Shortest inter-uranium distance 313pm (along the c-axis) is considerably smaller than the Hill limit (340pm).•UOsAl has paramagnetic ground state as the compounds with T=Fe and Ru, i.e. 3d and 4d analogues of Os.
Magnetization of a Ho2Fe14Si3 single crystal was measured in a steady magnetic field of up to 9 T and in pulsed fields of up to 60 T applied along the principal axes. Ho2Fe14Si3 is a ferrimagnet ...below TC = 480 K, has a spontaneous magnetic moment of about 8 μB/f.u. (at T = 4.2 K) and exhibits a large easy-plane magnetic anisotropy. There is also a certain anisotropy within the basal plane, the b axis 120 being the easy-magnetization direction. In fields applied along the a and b axes field-induced first-order phase transitions are observed at 29 T and at 22 T, respectively. Along the easy axis b we observe also an S-shaped anomaly at about 47 T, which does not correspond to a phase transition. A simple model predicts that the two observed first-order transitions are the only ones taking place in Ho2Fe14Si3; the magnetization should subsequently grow continuously and arrive at saturation at ∼100 T. This is in stark contrast to the behavior of the parent compound Ho2Fe17, where as many as three sequential first-order transitions are expected for H||b. The reason for the disparity is that the basal-plane anisotropy constant KHo is at least one order of magnitude smaller in Ho2Fe14Si3 than it is in Ho2Fe17.
•Ferrimagnet Ho2Fe14Si3 undergoes metamagnetic transitions in 29 T (a-axis) and 22 T (b-axis).•A large S-shape anomaly is observed at 47 T along the b axis.•Shape of magnetization curves supports previously developed theoretical model.
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