Potential High-performance Materials Research Articles

Cast Microstructure of a Complex Concentrated Noble Alloy Ag20Pd20Pt20Cu20Ni20

A complex concentrated noble alloy (CCNA) of equiatomic composition (Ag20Pd20Pt20Cu20Ni20–20 at. %) was studied as a potential high—performance material. The equiatomic composition was used so that this alloy could be classified in the subgroup of high—entropy alloys (HEA). The alloy was prepared by induction melting at atmospheric pressure, using high purity elements. The degree of metastability of the cast state was estimated on the basis of changes in the microstructure during annealing at high temperatures in a protective atmosphere of argon. Characterisation of the metallographically prepared samples was performed using a scanning electron microscope (SEM) equipped with an energy dispersive spectrometer (EDS), differential scanning calorimetry (DSC), and X–ray diffraction (XRD). Observation shows that the microstructure of the CCNA is in a very metastable state and multiphase, consisting of a continuous base of dendritic solidification—a matrix with an interdendritic region without other microstructural components and complex spheres. A model of the probable flow of metastable solidification of the studied alloy was proposed, based on the separation of L—melts into L1 (rich in Ni) and L2 (rich in Ag). The phenomenon of liquid phase separation in the considered CCNA is based on the monotectic reaction in the Ag−Ni system.

Recent progress in exotic polar topological states in ferroelectric nanostructures

Exotic ferroelectric topological states (such as vortex state) have received intensive attention in the past decade, creating a new area for exploring the emerging physical phenomena and functionalities, as well as new applications (such as memory). In recent years, a series of discoveries in novel topological states, such as vortex, central domain, skyrmion and meron states, has inspired an upsurge of research interests. Moreover, the effort to manipulate such a topological domain structure hints the possibilities for the local, deterministic control of order parameters so that the static interface conductivity can be successfully controlled at topologically protected domain walls. These encouraging discoveries create a new avenue to the fertile emerging physic phenomena, and offer new possibilities for developing potential high-performance materials and new nano-electronic devices based on these exotic states. In the past decade, this field has developed rapidly and become a hot research topic in ferroelectrics. In this paper, we review the recent progress in the field of exotic topological state in nanoferroelectrics, and discuss some existing problems and potential directions.

Foreign Particle Promoted Crystalline Nucleation for Growing High-Quality Ultrathin Rubrene Films.

Introducing foreign particles or agents as nucleator is an efficient way to promote crystallization in the crystal growth field, with the advantage to speed up the crystallizing rate and control the growth process. However, in the field of organic crystalline film growth, where the crystallization and morphology modulation are of significant importance in optoelectronics, this method has rarely been utilized. Particularly, some potential high-performance materials such as rubrene face the problem of crystallization during film formation. Here a strategy is reported to promote the crystallization of rubrene films in the initial stage assisted by foreign particles. Highly ordered thin film from the sub-monolayer stage can be achieved. Efficient charge transport and high mobility up to 2.95 cm(2) V(-1) s(-1) are achieved on thus ultrathin crystalline films. Such a method enables the well controlling of the film growth from the very early stage and produces uniform crystalline films with good reproducibility, thus highly promising to yield desired optoelectrical properties and applications.