211 research outputs found
Optimization Model and Pollution Treatment of Sintering Ore Distribution
sintering process plays an important role in iron and steel smelting process. The subsequent production of blast furnace ironmaking is directly affected by the quality of sinter. Among them, the proportion of raw materials and the advanced degree of sintering process are the two main factors affecting the quality of sinter. Because the control parameters of sintering process are too many and the physical and chemical process is too complex, it is difficult to establish and control the model accurately. Therefore, workers have long relied on experience to set temperature and other factors to engage in production, resulting in the quality of sinter is unstable, the cost is not easy to be controlled. Moreover, the flue gas produced in the sintering process will have different effects on the environment. Through the data analysis of the ore distribution scheme and the results of the physicochemical analysis of sinter in a steel plant, two aspects of the work are completed: one is to establish the optimal model of the cost of the sintering process, and the most suitable temperature for the sintering process. The second is the analysis of harmful components produced in sintering process
Tuning the Magnetic Ordering Temperature of Hexagonal Ferrites by Structural Distortion Control
To tune the magnetic properties of hexagonal ferrites, a family of
magnetoelectric multiferroic materials, by atomic-scale structural engineering,
we studied the effect of structural distortion on the magnetic ordering
temperature (TN). Using the symmetry analysis, we show that unlike most
antiferromagnetic rare-earth transition-metal perovskites, a larger structural
distortion leads to a higher TN in hexagonal ferrites and manganites, because
the K3 structural distortion induces the three-dimensional magnetic ordering,
which is forbidden in the undistorted structure by symmetry. We also revealed a
near-linear relation between TN and the tolerance factor and a power-law
relation between TN and the K3 distortion amplitude. Following the analysis, a
record-high TN (185 K) among hexagonal ferrites was predicted in hexagonal
ScFeO3 and experimentally verified in epitaxially stabilized films. These
results add to the paradigm of spin-lattice coupling in antiferromagnetic
oxides and suggests further tunability of hexagonal ferrites if more lattice
distortion can be achieved
Intertwined magnetic and nematic orders in semiconducting KFeAgTe
Superconductivity in the iron pnictides emerges from metallic parent
compounds exhibiting intertwined stripe-type magnetic order and nematic order,
with itinerant electrons suggested to be essential for both. Here we use X-ray
and neutron scattering to show that a similar intertwined state is realized in
semiconducting KFeAgTe (KFeAgTe) without
itinerant electrons. We find Fe atoms in KFeAgTe form
isolated blocks, separated by nonmagnetic Ag atoms. Long-range
magnetic order sets in below K, with magnetic moments
within the Fe blocks ordering into the stripe-type configuration. A
nematic order accompanies the magnetic transition, manifest as a structural
distortion that breaks the fourfold rotational symmetry of the lattice. The
nematic orders in KFeAgTe and iron pnictide parent
compounds are similar in magnitude and how they relate to the magnetic order,
indicating a common origin. Since KFeAgTe is a
semiconductor without itinerant electrons, this indicates that local-moment
magnetic interactions are integral to its magnetic and nematic orders, and such
interactions may play a key role in iron-based superconductivity.Comment: supplemental material available upon request, to be published in PR
Local breaking of four-fold rotational symmetry by short-range magnetic order in heavily overdoped Ba(FeCu)As
We investigate Cu-doped Ba(FeCu)As with transport,
magnetic susceptibility, and elastic neutron scattering measurements. In the
heavily Cu-doped regime where long-range stripe-type antiferromagnetic order in
BaFeAs is suppressed, Ba(FeCu)As (0.145 0.553) samples exhibit spin-glass-like behavior in magnetic
susceptibility and insulating-like temperature dependence in electrical
transport. Using elastic neutron scattering, we find stripe-type short-range
magnetic order in the spin-glass region identified by susceptibility
measurements. The persistence of short-range magnetic order over a large doping
range in Ba(FeCu)As likely arises from local arrangements
of Fe and Cu that favor magnetic order, with Cu acting as vacancies relieving
magnetic frustration and degeneracy. These results indicate locally broken
four-fold rotational symmetry, suggesting that stripe-type magnetism is
ubiquitous in iron pnictides.Comment: accepted by Physical Review B Rapid Communication
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