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As of today, metals and alloys are widely utilized as structural, mechanical, electrical, and magnetic materials in every aspect of technology and industry. The complexity and diversity of metals applications emphasize the need for a new production method to quickly and easily manufacture metallic components. Spark plasma sintering as a new solid-state sintering method has been recently developed to respond to these needs. Up to now, numerous papers and researches have been published in the field of spark plasma sintering and its ability to manufacture metallic samples. Density is a significant property that has a great influence on the physical, mechanical, and functional properties of metallic parts. To the best of our knowledge, there is no concrete paper that reviews the densification behavior of metals and alloys during spark plasma sintering and the effect of its parameters on the density of metallic samples. As a result, this article dedicated to addressing this need. In this mini-review, after a short description of spark plasma sintering method, the effects of each sintering parameters on densification behavior of metals and alloys are studied, and possible physical and microstructural factors which have the effect of densification behavior of metallic samples at various sintering conditions are reviewed. Finally, the recent advances in finite element modeling, which study the temperature and stress inhomogeneity in the SPS process, have been reviewed in this paper.

Two-dimensional transition metal dichalcogenides (TMDs) offer fascinating opportunities for fundamental nanoscale science and various technological applications. They are a promising platform for next generation optoelectronics and energy harvesting devices due to their exceptional characteristics at the nanoscale, such as tunable bandgap and strong light-matter interactions. The performance of TMD-based devices is mainly governed by the structure, composition, size, defects, and the state of their interfaces. Many properties of TMDs are influenced by the method of synthesis so numerous studies have focused on processing high-quality TMDs with controlled physicochemical properties. Plasma-based methods are cost-effective, well controllable, and scalable techniques that have recently attracted researchers' interest in the synthesis and modification of 2D TMDs. TMDs' reactivity toward plasma offers numerous opportunities to modify the surface of TMDs, including functionalization, defect engineering, doping, oxidation, phase engineering, etching, healing, morphological changes, and altering the surface energy. Here we comprehensively review all roles of plasma in the realm of TMDs. The fundamental science behind plasma processing and modification of TMDs and their applications in different fields are presented and discussed. Future perspectives and challenges are highlighted to demonstrate the prominence of TMDs and the importance of surface engineering in next-generation optoelectronic applications. [ABSTRACT FROM AUTHOR]

The need for fully dense material with well-engineered microstructures has led to the promising emergence of innovative sintering technologies among which the Spark Plasma Sintering (SPS) is one of the most favorite. Unlike the conventional sintering processes, SPS takes advantage of a current flow passing through the sintering die and metallic powders by which fast densification with minimal grain growth and enhanced physicomechanical properties can be obtained. Albeit there is a growing interest in the exploitation of SPS in producing sufficiently consolidated metallic parts, no analytical review has been released over the effects of SPS parameters on the densification behavior, microstructure evolution, and resultant physicomechanical properties of metallic parts and their alloys. In the present review, recent developments and ongoing challenges in modeling the SPS of metallic systems are thoroughly explored. Then, the effects of main SPS parameters including sintering temperature, dwell time, heating rate, and pressure on the microstructure and physicomechanical properties of metals and alloys are comprehensively investigated. These properties are categorized into two groups: (i) physical properties including relative density, electrical and thermal conductivities; (ii) mechanical properties with a systematic focus on hardness, elastic modulus, and tensile, compressive, and bending strengths. In each section, the general trends along which SPS parameters grow to affect each corresponding property are comprehensively discussed. Additionally, various microstructural phenomena being more likely to occur at the given metallic systems are fully addressed. The present work seeks to elaborate on the aforementioned issues and provide an overview of the unresolved challenges and proposed solutions to them. [ABSTRACT FROM AUTHOR]

Metallic or ceramic micro/nanoporous materials have attracted particular attention due to some interesting structural and functional properties. There exist a variety of methods for producing porous materials by which optimized features can be reached. Spark plasma sintering (SPS) is one of these new-emerging approaches. This technique is often combined with conventional technologies and produce a variety of porous structures with tailorable microstructure and physicomechanical properties. This review addresses SPS and obtainable porous materials with nanoscale and microscale microstructural features. The processing methods, microstructural phenomena, and physicomechanical properties of these materials are discussed in some details, along with the likely future directions required for this novel field. [ABSTRACT FROM AUTHOR]

We report the presence of sub-nm MoO x clusters formed on basal planes of the 2H MoS 2 crystals during thermal oxidative etching in air at a temperature of 370 °C. Using high resolution non-contact atomic force microscopy (AFM) we provide a histogram of their preferred heights. The AFM results combined with density functional theory (DFT) simulations show remarkably well that the MoO x clusters are predominantly single MoO 3 molecules and their dimers at the sulfur vacancies. Additional Raman spectroscopy, and energy and wavelength dispersive X-ray spectroscopies as well as Kelvin probe AFM investigations confirmed the presence of the MoO 3 /MoO x species covering the MoS 2 surface only sparsely. The X-ray absorption near edge spectroscopy data confirm the MoO 3 stoichiometry. Taken together, our results show that oxidative etching and removal of Mo atoms at the atomic level follow predominantly via formation of single MoO 3 molecules. Such findings confirm the previously only proposed oxidative etching stoichiometry., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)