metallic phase
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2022 ◽  
Vol 375 ◽  
pp. 115853
Author(s):  
Zhiqiang Wei ◽  
Tingli Yu ◽  
Lizhi Qian ◽  
Jiayuan Chen ◽  
Zhiyuan Wang ◽  
...  

2022 ◽  
Vol 60 (1) ◽  
pp. 14-25
Author(s):  
Hanjung Kwon

The metallic binder in WC-Co hard metals was effectively strengthened using the solid solution phases of Co and W. These metallic phases of Co and W (Co1-xWx, x<1), which consist of two kinds of structures (FCC and HCP), were successfully formed by hydrogen reduction of milled oxides mixtures (Co3O4 and WO3) at over 1000 oC. When hard metals are fabricated by pressureless sintering of mixed WC and Co1-xWx, the hard metals containing the WC2 and M6C phases (Co2W4C and Co4W2C) have brittleness, which degrades their mechanical properties, like hard metals fabricated from mixtures of WC, Co, and W. By rapidly sintering the WC-Co1-xWx hard metals for 5 min the WC2 and M6C phases were eliminated, and a two-phase (WC and the metallic phase of Co and W) region was successfully obtained. The mechanical properties of the WC-Co1-xWx hard metals showed higher values for both hardness (max. 18.8 GPa) and fracture toughness (8.5 MPa·m1/2) than conventional WC-Co hard metal (HV: 15.9 GPa, KIC: 6.9 MPa·m1/2). The enhancement in toughness was attributed to the solid solution strengthening of the metallic binder and the elimination of the WC2 and M6C phases. The suppression of grain growth due to the short duration of sintering also played a positive role in improving the hardness of the WC-Co1-xWx hard metals. The phase-controlled solid solution metallic binder could be the key material to enhance the hardness and toughness of hard metals.


2022 ◽  
Vol 19 (1) ◽  
pp. 1721
Author(s):  
Priyanka Bhardwaj ◽  
Manidipa Roy ◽  
Sanjay Kumar Singh

This paper presents 2 dimensional (2D) and 1 dimensional (1D) gold (Au) coated VO2 (Vanadium Dioxide) nanogratings based tunable plasmonic switch. VO2 is a phase changing material and hence exhibits phase transition from semiconductor to metallic phase approximately at 67 ºC or 340 K (critical temperature) which can be achieved by exposure to IR radiation, application of voltage, heating, etc. and there is a huge contrast between optical properties of its metallic and insulating phases and hence that can be utilized to implement VO2 based optical switches. These VO2 based gratings couple the incident optical radiation to plasmonic waveguide modes which in turn leads to high electromagnetic field enhancement in the gaps between the nanogratings. The proposed Au coated VO2 nanogratings can be fabricated by using current state of art fabrication techniques and provides switchability of the order of femtoseconds. Hence the optical switching explained in our paper can be used fast switching applications. For an optimum switch our aim is to maximize its differential reflectance spectra between the 2 states of VO2, i.e., metallic and semiconductor phases. Rigorous Coupled Wave Analysis (RCWA) reveals that wavelengths for maximum differential reflectance can be optimized over a large spectral regime by varying various parameters of nanogratings for example groove height (h), width (w), gap (g) between the gratings, and thickness (t) of Au coating over VO2 by simulation using RCWA for maximum differential reflectance between VO2 metal and semiconductor phase, i.e., the switching wavelengths can be tuned by varying grating parameters and thus we can have optimum optical switch.


Nanomaterials ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 110
Author(s):  
Jing Guo ◽  
Kai Liu

With the demand for low contact resistance and a clean interface in high-performance field-effect transistors, two-dimensional (2D) hetero-phase homojunctions, which comprise a semiconducting phase of a material as the channel and a metallic phase of the material as electrodes, have attracted growing attention in recent years. In particular, MoTe2 exhibits intriguing properties and its phase is easily altered from semiconducting 2H to metallic 1T′ and vice versa, owing to the extremely small energy barrier between these two phases. MoTe2 thus finds potential applications in electronics as a representative 2D material with multiple phases. In this review, we briefly summarize recent progress in 2D MoTe2 hetero-phase homojunctions. We first introduce the properties of the diverse phases of MoTe2, demonstrate the approaches to the construction of 2D MoTe2 hetero-phase homojunctions, and then show the applications of the homojunctions. Lastly, we discuss the prospects and challenges in this research field.


2021 ◽  
Author(s):  
Assoc. Prof. Dr. Ahmet YONETKEN

Abstract The specimens, magnetic properties materials, and microwave characteristics of Ni coated Fe and Co composites were researched by specimens produced by microwave furnace sintering at 1100°C temperature. A uniform nickel deposit on Fe-Co particles was coated previously to sintering by electroless coating deposition procedure. A composite consisting of quaternary additions, a metallic phase, Fe-Co inside of Ni matrix has been prepared under in a neutral atmosphere environment then microwave sintered. X-Ray Diffraction, SEM(Scanning-Electron-Microscope), Empedans Phase Analyzer were utilized to obtain structural data and to determine magnetic and electrical features such as dielectric and conductivity at the temperature range of 25-400C. The ferromagnetic resonance varied from 10 Hz to 1GHz and measurements were employed to characterize the features of the specimens. Empirical of findings obtained for the composition (Fe-%25Co)50Ni at 1100°C recommend that the best conductivity and hardness were obtained with 50Ni addition at a sintering temperature of 1100°C.


Author(s):  
Katsunori Tagami ◽  
Jun NARA ◽  
Takahisa Ohno ◽  
Mamoru Usami

Abstract We propose an efficient theoretical method to take into account the core-hole spin density in the projector augmented wave (PAW) method, combined with spin un-polarized pseudopotentials and the planewave basis set. We apply this method to the calculation of absolute core level X-ray photoelectron spectroscopy (XPS) binding energies of WS2 and its related materials, and find the following points. First, inclusion of core-hole spin in the core-exited state is essential for accurate description of the binding energies, especially for light elements. Second, the calculated absolute binding energies show excellent agreement with experimental results. Finally, when oxygen atoms are incorporated in the basal plane of WS2 in the metallic phase, the O 1s binding energy is expected to appear at lower energy than the corresponding value in the semiconducting phase.


2021 ◽  
Vol 61 (12) ◽  
pp. 2929-2936
Author(s):  
Naoya Matsushita ◽  
Kosuke Awaya ◽  
Keijiro Saito ◽  
Masakatsu Hasegawa

2021 ◽  
Vol 385 ◽  
pp. 111537
Author(s):  
Takanari Fukuda ◽  
Akifumi Yamaji ◽  
Xin Li ◽  
Jean-François Haquet ◽  
Anne Boulin
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