First-principles investigation of the site preference and alloying effect of Mo, Ta and platinum group metals in γ′-Co3(Al,W)

2009 ◽  
Vol 60 (8) ◽  
pp. 659-662 ◽  
Author(s):  
Min Chen ◽  
Chong-Yu Wang
Keyword(s):  
First Principles ◽  
Platinum Group Metals ◽  
Site Preference ◽  
Alloying Effect ◽  
Platinum Group

First-Principles Investigations on the Elastic Properties of Platinum Group Metals (Pt, Pd, and Ru)

2019 ◽  
Vol 944 ◽  
pp. 761-769 ◽  
Author(s):  
Ying Jie Sun ◽  
Kai Xiong ◽  
Shun Meng Zhang ◽  
Yong Mao
Keyword(s):  
Mechanical Properties ◽  
First Principles ◽  
Density Functional ◽  
Elastic Anisotropy ◽  
Platinum Group Metals ◽  
First Principles Calculations ◽  
New Materials ◽  
Functional Theory ◽  
Platinum Group ◽  
Microscopic Deformation

The structural, mechanical, and thermodynamic properties of platinum group metals (Pt, Pd, and Ru) were systematically investigated by first-principles calculations based on density functional theory. Comparative studies show that Ru has the best comprehensive mechanical properties. Based on the Pugh’s rule and Poisson’s ratio, it is judged that Pt and Pd are ductility materials, and Ru exhibits obvious brittleness. Furthermore, the elastic anisotropy is also discussed by plotting both the 3D contours and the 2D planar projections of Young's modulus and shear modulus. The predicted elastic anisotropy factors indicate that the degree of elastic anisotropy of Pd is significant, while Ru has the smallest elastic anisotropy. By using the Clarke’s model, the minimum thermal conductivities of these metals have also been analyzed, and the results indicate that the low minimum thermal conductivity is proportional to the Debye temperature ΘD. The above results can provide a valuable reference for revealing the microscopic deformation mechanism and designing new materials.

Alloying and magnetic disordering effects on the phase stability of Co2 Y Ga (Y =Cr, V, and Ni) alloys: A first-principles study

2021 ◽  
Author(s):  
Chun-Mei Li ◽  
Shun-Jie Yang ◽  
Jin-Ping Zhou
Keyword(s):  
Martensitic Transformation ◽  
Phase Stability ◽  
First Principles ◽  
Elastic Anisotropy ◽  
Cubic Phase ◽  
Site Preference ◽  
Alloying Effect ◽  
Ni Alloys ◽  
Jahn Teller ◽  
Jahn Teller Effect

Abstract The alloying and magnetic disordering effects on the site occupation, elastic property, and phase stability of Co2 YGa (Y=Cr, V, and Ni) shape memory alloys are systematically investigated by using the first-principles exact muffin-tin orbitals method. It is shown that with increasing the magnetic disordering degree (y), their tetragonal shear elastic constant C' ((C 11 - C 12)/2) of the L21 phase decreases whereas the elastic anisotropy (A) increases, and upon tetragonal distortions the cubic phase gets more and more unstable. Co2CrGa and Co2VGa alloys with y ≥ 0.2 thus can show the martensitic transformation (MT) from L21 to D022 as well as Co2NiGa. In off-stoichiometric alloys, the site preference is controlled by both the alloying and magnetic effects. At the FM state, the excess Ga atom always tends to take the Y sublattice, whereas the excess Co atom favors the Y site when Y=Cr, and the excess Y atom prefers the Co site when Y=Ni. The Ga-deficient Y=V alloys can occur the MT also at the FM state by means of Co or V doping, and the MT temperature (T M ) should increase with their addition. In the corresponding FM Y=Cr alloys, nevertheless, with Co or Cr substituting for Ga, the reentrant MT (RMT) from D022 to L21 is promoted and then T M for the RMT should decrease. The alloying effect on the MT of these alloys is finally well explained by means of the Jahn-Teller effect at the paramagnetic (PM) state. At the FM state, it may originate from the competition between the austenite and martensite about their strength of the covalent banding between Co and Ga as well as Y and Ga.

Site preference and atomic ordering in the ternary Rh5Ga2As: first-principles calculations

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Nilanjan Roy ◽  
Sucharita Giri ◽  
Harshit ◽  
Partha P. Jana
Keyword(s):  
Total Energy ◽  
First Principles ◽  
Density Functional ◽  
Structure Type ◽  
Site Preference ◽  
X Ray Diffraction ◽  
Atomic Ordering ◽  
Functional Theory ◽  
The Stability ◽  
Bonding Characteristics

Abstract The site preference and atomic ordering of the ternary Rh5Ga2As have been investigated using first-principles density functional theory (DFT). An interesting atomic ordering of two neighboring elements Ga and As reported in the structure of Rh5Ga2As by X-ray diffraction data only is confirmed by first-principles total-energy calculations. The previously reported experimental model with Ga/As ordering is indeed the most stable in the structure of Rh5Ga2As. The calculation detected that there is an obvious trend concerning the influence of the heteroatomic Rh–Ga/As contacts on the calculated total energy. Interestingly, the orderly distribution of As and Ga that is found in the binary GaAs (Zinc-blende structure type), retained to ternary Rh5Ga2As. The density of states (DOS) and Crystal Orbital Hamiltonian Population (COHP) are calculated to enlighten the stability and bonding characteristics in the structure of Rh5Ga2As. The bonding analysis also confirms that Rh–Ga/As short contacts are the major driving force towards the overall stability of the compound.

scholarly journals Janus Nanocages of Platinum‐Group Metals and Their Use as Effective Dual‐Electrocatalysts

2021 ◽  
Vol 133 (18) ◽  
pp. 10472-10480
Author(s):  
Jiawei Zhu ◽  
Lang Xu ◽  
Zhiheng Lyu ◽  
Minghao Xie ◽  
Ruhui Chen ◽  
...  
Keyword(s):  
Platinum Group Metals ◽  
Platinum Group
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