scholarly journals Theoretical and Experimental Studies of the Structural, Phase Stability and Elastic Properties of AlCrTiFeNi Multi-Principle Element Alloy

Materials ◽  
2020 ◽  
Vol 13 (19) ◽  
pp. 4353
Author(s):  
Li Liu ◽  
Ramesh Paudel ◽  
Yong Liu ◽  
Xiao-Liang Zhao ◽  
Jing-Chuan Zhu
Keyword(s):  
Structural Stability ◽  
Deformation Behavior ◽  
Density Functional ◽  
Low Cost ◽  
Structural Phase ◽  
Experimental Studies ◽  
Density Functional Theory Calculations ◽  
Mixing Enthalpy ◽  
Size Difference ◽  
Valence Electron Concentration

The fundamental challenge for creating the crystal structure model used in a multi-principle element design is the ideal combination of atom components, structural stability, and deformation behavior. However, most of the multi-principle element alloys contain expensive metallic and rare earth elements, which could limit their applicability. Here, a novel design of low-cost AlCrTiFeNi multi-principle element alloy is presented to study the relationship of structure, deformation behavior, and micro-mechanism. This structured prediction of single-phase AlCrTiFeNi by the atomic-size difference, mixing enthalpy ΔHmix and valence electron concentration (VEC), indicate that we can choose the bcc-structured solid solution to design the AlCrTiFeNi multi-principle element alloy. Structural stability prediction by density functional theory calculations (DFT) of single phases has verified that the most advantageous atom occupancy position is (FeCrNi)(AlFeTi). The experimental results showed that the structure of AlCrTiFeNi multi-principle element alloy is bcc1 + bcc2 + L12 phases, which we propose as the fundamental reason for the high strength. Our findings provide a new route by which to design and obtain multi-principle element alloys with targeted properties based on the theoretical predictions, first-principles calculations, and experimental verification.

scholarly journals Unlocking surface octahedral tilt in two-dimensional Ruddlesden-Popper perovskites

2022 ◽  
Vol 13 (1) ◽  
Author(s):  
Yan Shao ◽  
Wei Gao ◽  
Hejin Yan ◽  
Runlai Li ◽  
Ibrahim Abdelwahab ◽  
...  
Keyword(s):  
Density Functional ◽  
Carrier Transport ◽  
Plane Surface ◽  
Structural Phase ◽  
Density Functional Theory Calculations ◽  
Spin Splitting ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Out Of Plane ◽  
Inversion Asymmetry

AbstractMolecularly soft organic-inorganic hybrid perovskites are susceptible to dynamic instabilities of the lattice called octahedral tilt, which directly impacts their carrier transport and exciton-phonon coupling. Although the structural phase transitions associated with octahedral tilt has been extensively studied in 3D hybrid halide perovskites, its impact in hybrid 2D perovskites is not well understood. Here, we used scanning tunneling microscopy (STM) to directly visualize surface octahedral tilt in freshly exfoliated 2D Ruddlesden-Popper perovskites (RPPs) across the homologous series, whereby the steric hindrance imposed by long organic cations is unlocked by exfoliation. The experimentally determined octahedral tilts from n = 1 to n = 4 RPPs from STM images are found to agree very well with out-of-plane surface octahedral tilts predicted by density functional theory calculations. The surface-enhanced octahedral tilt is correlated to excitonic redshift observed in photoluminescence (PL), and it enhances inversion asymmetry normal to the direction of quantum well and promotes Rashba spin splitting for n > 1.

Optical properties of magnesium nanorods using time dependent density functional theory calculations

2018 ◽  
Vol 20 (45) ◽  
pp. 28903-28909 ◽  
Author(s):  
Junais Habeeb Mokkath
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Low Cost ◽  
Density Functional Theory Calculations ◽  
Time Dependent ◽  
Plasmonic Nanostructures ◽  
Functional Theory ◽  
Earth Abundant ◽  
Potential Alternative ◽  
Dependent Density

Plasmonic nanostructures made of Earth-abundant and low-cost metals such as aluminum and magnesium have recently emerged as a potential alternative candidate to conventional plasmonic metals such as gold and silver.

scholarly journals Influence of Varying Functionalization on the Peroxidase Activity of Nickel(II)–Pyridine Macrocycle Catalysts: Mechanistic Insights from Density Functional Theory

Computation ◽  
2020 ◽  
Vol 8 (2) ◽  
pp. 52
Author(s):  
Jerwin Jay E. Taping ◽  
Junie B. Billones ◽  
Voltaire G. Organo
Keyword(s):  
Density Functional Theory ◽  
Proton Transfer ◽  
Density Functional ◽  
Experimental Studies ◽  
Density Functional Theory Calculations ◽  
Catalytic Performance ◽  
Stoichiometric Ratio ◽  
Functional Theory ◽  
Pendant Arm ◽  
Spin Singlet

Nickel(II) complexes of mono-functionalized pyridine-tetraazamacrocycles (PyMACs) are a new class of catalysts that possess promising activity similar to biological peroxidases. Experimental studies with ABTS (2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid), substrate) and H2O2 (oxidant) proposed that hydrogen-bonding and proton-transfer reactions facilitated by their pendant arm were responsible for their catalytic activity. In this work, density functional theory calculations were performed to unravel the influence of pendant arm functionalization on the catalytic performance of Ni(II)–PyMACs. Generated frontier orbitals suggested that Ni(II)–PyMACs activate H2O2 by satisfying two requirements: (1) the deprotonation of H2O2 to form the highly nucleophilic HOO−, and (2) the generation of low-spin, singlet state Ni(II)–PyMACs to allow the binding of HOO−. COSMO solvation-based energies revealed that the O–O Ni(II)–hydroperoxo bond, regardless of pendant arm type, ruptures favorably via heterolysis to produce high-spin (S = 1) [(L)Ni3+–O·]2+ and HO−. Aqueous solvation was found crucial in the stabilization of charged species, thereby favoring the heterolytic process over homolytic. The redox reaction of [(L)Ni3+–O·]2+ with ABTS obeyed a 1:2 stoichiometric ratio, followed by proton transfer to produce the final intermediate. The regeneration of Ni(II)–PyMACs at the final step involved the liberation of HO−, which was highly favorable when protons were readily available or when the pKa of the pendant arm was low.

Janus monolayer of WSeTe, a new structural phase transition material driven by electrostatic gating

Nanoscale ◽  
2018 ◽  
Vol 10 (46) ◽  
pp. 21629-21633 ◽  
Author(s):  
Yajing Sun ◽  
Zhigang Shuai ◽  
Dong Wang
Keyword(s):  
Phase Transition ◽  
Density Functional Theory ◽  
Structural Phase Transition ◽  
Density Functional ◽  
Structural Phase ◽  
Density Functional Theory Calculations ◽  
Functional Theory ◽  
Electrostatic Gating ◽  
Phase Transition Kinetics

By density functional theory calculations, we show that the Janus monolayer of WSeTe has faster semiconductor–semimetal phase transition kinetics than MoTe2.

scholarly journals Electronic and Optical Properties of Sodium Niobate: A Density Functional Theory Study

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Daniel Fritsch
Keyword(s):  
Density Functional Theory ◽  
Optical Properties ◽  
Lead Zirconate Titanate ◽  
Density Functional ◽  
Room Temperature ◽  
Structural Phase ◽  
Density Functional Theory Calculations ◽  
Sodium Niobate ◽  
Functional Theory ◽  
Electronic And Optical Properties

In recent years, much effort has been devoted to replace the most commonly used piezoelectric ceramic lead zirconate titanate Pb[ZrxTi1−x]O3 (PZT) with a suitable lead-free alternative for memory or piezoelectric applications. One possible alternative to PZT is sodium niobate as it exhibits electrical and mechanical properties that make it an interesting material for technological applications. The high-temperature simple cubic perovskite structure undergoes a series of structural phase transitions with decreasing temperature. However, particularly the phases at room temperature and below are not yet fully characterised and understood. Here, we perform density functional theory calculations for the possible phases at room temperature and below and report on the structural, electronic, and optical properties of the different phases in comparison to experimental findings.

Rational design of a molecularly imprinted polymer for dinotefuran: theoretical and experimental studies aimed at the development of an efficient adsorbent for microextraction by packed sorbent

The Analyst ◽  
2018 ◽  
Vol 143 (1) ◽  
pp. 141-149 ◽  
Author(s):  
Camilla Fonseca Silva ◽  
Keyller Bastos Borges ◽  
Clebio Soares do Nascimento
Keyword(s):  
Molecularly Imprinted Polymer ◽  
Density Functional ◽  
Rational Design ◽  
Experimental Studies ◽  
Density Functional Theory Calculations ◽  
Imprinted Polymer ◽  
Functional Theory ◽  
Molecularly Imprinted ◽  
Functional Monomers ◽  
Packed Sorbent

In this work, we studied theoretically the formation process of a molecularly imprinted polymer (MIP) for dinotefuran (DNF), by testing distinct functional monomers (FM) in various solvents through density functional theory calculations.

(Cu, Ag)-DOPED ZnS WITH WIDE VISIBLE LIGHT RANGE ABSORPTION FOR WATER SPLITTING: A THEORETICAL AND EXPERIMENTAL STUDY

2019 ◽  
Vol 27 (04) ◽  
pp. 1950139
Author(s):  
XIAOBO CHEN ◽  
WEIWEI LIU ◽  
ZHIHAI ZHANG ◽  
WEN YANG ◽  
PEIZHI YANG
Keyword(s):  
Visible Light ◽  
Water Splitting ◽  
Density Functional ◽  
Energy Levels ◽  
Experimental Studies ◽  
Density Functional Theory Calculations ◽  
Chemical Precipitation ◽  
Precipitation Method ◽  
Functional Theory ◽  
Light Region

Photocatalytic water splitting using a semiconductor photocatalyst is a promising process for direct solar energy conversion. In this study, the feasibility of the photocatalytic H2 evolution on (Cu, Ag)- doped ZnS catalysts under visible light irradiation has been investigated by using first-principles density functional theory calculations and experimental studies. The present results reveal that (Cu, Ag)-doped ZnS structures have relatively small formation energy, implying that they are more easily obtained in experiment. Moreover, the absorption is enhanced obviously in the visible-light region for (Cu, Ag)-doped ZnS, but their energy levels are still suitable for water splitting to generate H2, which means that (Cu, Ag)-doped ZnS structures are promising candidate photocatalyst materials for H2 production driven by visible light. ZnS and (Cu, Ag)-doped ZnS were prepared using chemical precipitation method. (Cu, Ag)-doped ZnS samples showed an improved photocatalytic activity compared with undoped ZnS. Ag-doped ZnS (0.15 g L[Formula: see text] has the highest hydrogen evolution rate of 794.6 [Formula: see text]mol[Formula: see text] h[Formula: see text] [Formula: see text] g[Formula: see text] at pH 3 (0.1 M Na2S solution as a sacrificing agent).

Combined Computational and Experimental Study of the Pressure Dependence of the Structural and Vibrational Properties on Solid Naphthalene C10H8

2018 ◽  
Vol 914 ◽  
pp. 175-181
Author(s):  
Ling Ping Xiao ◽  
Li Zeng ◽  
Xue Yang
Keyword(s):  
Density Functional ◽  
Intramolecular Interaction ◽  
Applied Pressure ◽  
Experimental Studies ◽  
Density Functional Theory Calculations ◽  
Optical Data ◽  
Vibrational Properties ◽  
Intermolecular Distances ◽  
Almost All

We present high-quality optical data and density functional theory calculations for the structural and vibrational properties of solid naphthalene (C10H8) under pressure up to 21.5 GPa. Our results demonstrate that almost all the modes shift toward higher frequencies and some peaks are broadened with increasing pressure. Comparing the pressure effect on the shortest intermolecular distances and on the bond lengths we confirm the expected result that the intramolecular interaction are less sensitive to pressure than the intermolecular interactions. These findings are shown to be in agreement with experimental results and hint towards the evolution of intermolecular interaction with pressure. Moreover, within our data the lattice modes exhibit more drastic changes than intramolecular modes, which are due to there being greater intermolecular distortions than intramolecular under applied pressure. In combination with theoretical and experimental studies, these results permit detailed characterization of the structural and vibrational changes of naphthalene as a function of pressure.

scholarly journals Pt(dithiolene)-Based Colorimetric Chemosensors for Multiple Metal-Ion Sensing

2021 ◽  
Vol 13 (15) ◽  
pp. 8160
Author(s):  
Heawon Son ◽  
Seohyeon Jang ◽  
Gayoung Lim ◽  
Taeyong Kim ◽  
Inho Nam ◽  
...  
Keyword(s):  
Transition Metal ◽  
Metal Ions ◽  
Metal Ion ◽  
Density Functional ◽  
Low Cost ◽  
Density Functional Theory Calculations ◽  
Transition Metal Ions ◽  
Field Analysis ◽  
Ion Sensing ◽  
Metal Ion Sensing

Colorimetric chemosensors are widely employed for in-field analysis to detect transition metal ions in real-time with the naked eye. Colorimetric chemosensors have attracted considerable attention because they can conveniently provide quantitative and qualitative information at a low cost. However, the development of colorimetric chemosensors for multiple-ion sensing where metal cations coexist has been limited. For this reason, we developed a new type of transition metal ion sensing material by selectively replacing functional groups on (diphosphine)Pt(dmit) molecules. The terminal groups of the diphosphine ligand were successfully substituted by the cyclohexyl groups, increasing the electron density of the thione moiety. Due to the electron donation ability of the cyclohexyl terminal groups, the proposed chemosensing material was able to selectively detect the mixture of Hg2+, Cu2+, and Ag+ in the presence of many types of interfering cations. To gain insight into the binding mechanisms between the metal ions and the developed (dchpe)Pt(dmit) molecule, density functional theory calculations were also performed.

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