Unique atomic arrangements in nonthermodynamic solid solutions containing thermodynamically immiscible elements facilitate the introduction of new functionalities in various classes of materials, such as alloys, ceramics, and coordination polymers. Although high-temperature quenching has been widely used for synthesizing such materials with the aid of the surface effect and high configuration entropy, it is not applicable to materials that are unstable at high temperatures and contain only a few constituents. Thus, a new synthesis strategy is required. In this study, we demonstrated that a low-temperature topochemical reaction facilitates the extension of the conventional solid-solubility limit in layered double hydroxides (LDHs), a class of natural and synthetic lamellar compounds. Using a pristine layered oxide, Na[Ni 1−x Fe x ]O 2 (0 < x < 1.0), the solid-solubility limit of LDHs () could be extended from x = 0.33 to 0.59. Furthermore, compared to LDHs (x = 0.30), the obtained LDHs (x = 0.59) exhibited a 20-fold higher selectivity for fluoride ions than for sulfate ions. This selectivity possibly originated from a trivalent-cation clustering of Fe 3+ −Fe 3+ neighbors in the LDH hydroxide layers; this caused a steric hindrance between sulfate and chloride ions in the interlayer space while preventing hindrance between fluoride and chloride ions. We expect that this study will guide the design of unexplored nonthermodynamic solid solutions.
We present a novel practical design optimization for the primary core in an induction heating roll, which significantly affects the heating performance. To optimize the 3D eddy current field problem within an acceptable CPU time, we effectively combine 2D magnetostatic optimization and 3D coupled magnetic-thermal FEM. For the 2D optimization, we adopt the level-set method, which has an advantage of being able to derive a feasible shape. However, the disadvantage is that its result occasionally falls into a local optimal solution. To overcome this disadvantage, we propose conducting the initial conceptual design with the linear level-set method before using the nonlinear level-set method to expand the search domain. Furthermore, we incorporate the parallelized move-limit strategy into the level-set method to prevent the configuration from undergoing excess deformation by the operation for the area constraint. Finally, the 2D optimal shape obtained using our new level-set method is converted into a straight line cross-sectional configuration to improve manufacturability, and the final 3D design is created with slits. The final 3D design obtained as a result of the 3D FEM successfully improves both the heating speed and temperature uniformity on the surface of the heating part under the same conditions of input AC current and material volume.
It is very important to design electrical machineries with high efficiency from the point of view of saving energy. Therefore, topology optimization (TO) is occasionally used as a design method for improving the performance of electrical machinery under the reasonable constraints. Because TO can achieve a design with much higher degree of freedom in terms of structure, there is a possibility for deriving the novel structure which would be quite different from the conventional structure. In this paper, topology optimization using sequential linear programming using move limit based on adaptive relaxation is applied to two models. The magnetic shielding, in which there are many local minima, is firstly employed as firstly benchmarking for the performance evaluation among several mathematical programming methods. Secondly, induction heating model is defined in 2-D axisymmetric field. In this model, the magnetic energy stored in the magnetic body is maximized under the constraint on the volume of magnetic body. Furthermore, the influence of the location of the design domain on the solutions is investigated.
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