Pressure-induced phase transition in titanium alloys

2018 ◽  
Vol 32 (12) ◽  
pp. 1850141
Author(s):  
R. Murugeswari ◽  
R. Rajeswarapalanichamy ◽  
A. Milton Franklin Benial
Keyword(s):  
Density Functional ◽  
High Pressures ◽  
Ambient Pressure ◽  
Hexagonal Phase ◽  
Structural Phase ◽  
Normal Pressure ◽  
Simulation Code ◽  
Ni Alloys ◽  
Debye Temperatures ◽  
Good Agreement

The structural, elastic, magnetic and electronic properties of titanium-based ferromagnetic (FM) TiX (X = Fe, Co, Ni) alloys are investigated by the first principles calculations based on density functional theory using the Vienna ab initio simulation code. At ambient pressure, all the three alloys TiFe, TiCo and TiNi are highly stable in CsCl structure. The calculated lattice parameters and ground state properties are in good agreement with the available theoretical and experimental results. The density of states explains that these alloys possess the metallic nature at normal and high pressures. A pressure-induced structural phase transitions from CsCl to NaCl phase at 46 GPa and NaCl to ZB phase at 49 GPa in TiFe, CsCl to ZB phase in TiCo at 52 GPa, CsCl to hexagonal phase at 22 GPa and hexagonal to ZB phase at 66 GPa in TiNi are observed. The calculated Debye temperatures of TiX (X = Fe, Co, Ni) alloys are in good agreement with earlier reports. Binding energy shows that the TiCo is the most stable alloy. The magnetic property of TiX (X = Fe, Co, Ni) alloys reveals that TiFe is stable in nonmagnetic phase and the other two alloys, TiCo and TiNi, are stable in FM phase at normal pressure.

PRESSURE-INDUCED ELECTRONIC PHASE TRANSITIONS AND SUPERCONDUCTIVITY IN TITANIUM

2009 ◽  
Vol 23 (05) ◽  
pp. 723-741 ◽  
Author(s):  
K. IYAKUTTI ◽  
C. NIRMALA LOUIS ◽  
S. ANURATHA ◽  
S. MAHALAKSHMI
Keyword(s):  
High Pressure ◽  
Band Structure ◽  
Fermi Surface ◽  
High Pressures ◽  
Ambient Pressure ◽  
Structural Phase ◽  
Normal Pressure ◽  
Orbital Method ◽  
Superconducting Transition ◽  
Electronic Band

The electronic band structure, density of states, structural phase transition, superconducting transition and Fermi surface cross section of titanium ( Ti ) under normal and high pressures are reported. The high pressure band structure exhibits significant deviations from the normal pressure band structure due to s → d transition. On the basis of band structure and total energy results obtained using tight-binding linear muffin-tin orbital method (TB LMTO), we predict a phase transformation sequence of α( hcp ) → ω (hexagonal) → γ (distorted hcp) → β (bcc) in titanium under pressure. From our analysis, we predict a δ (distorted bcc) phase which is not stable at any high pressures. At ambient pressure, the superconducting transition occurs at 0.354 K. When the pressure is increased, it is predicted that, Tc increases at a rate of 3.123 K/Mbar in hcp–Ti . On further increase of pressure, Tc begins to decrease at a rate of 1.464 K/Mbar. The highest value of Tc(P) estimated is 5.043 K for hcp–Ti , 4.538 K for ω– Ti and 4.85 K for bcc – Ti . From this, it is inferred that the maximum value of Tc(P) is rather insensitive to the crystal structure of Ti . The nonlinearities in Tc(P) is explained by considering the destruction and creation of new parts of Fermi surface at high pressure. At normal pressure, the hardness of Ti is in the following order: ω- Ti > hcp - Ti > bcc- Ti > γ- Ti .

Structural, elastic, magnetic and electronic properties of TiX2(X = Cr, Mn) alloys

2019 ◽  
Vol 33 (12) ◽  
pp. 1950115
Author(s):  
R. Murugeswari ◽  
A. Milton Franklin Benial ◽  
R. Rajeswarapalanichamy
Keyword(s):  
Electronic Properties ◽  
Density Functional ◽  
Ambient Pressure ◽  
Structural Phase ◽  
Ferromagnetic Materials ◽  
Hexagonal Structure ◽  
First Principles Calculations ◽  
Simulation Code ◽  
Functional Theory ◽  
Lattice Constants

The structural, elastic, magnetic and electronic properties of titanium-based alloys TiX2(X = Cr, Mn) are investigated by the first-principles calculations based on density functional theory using the Vienna ab-initio simulation code. The lattice constants of TiX2(X = Cr, Mn) alloys are optimized for various possible structures such as hexagonal, tetragonal and orthorhombic. TiX2(X = Cr, Mn) alloys are highly stable in hexagonal structure with the space group P63/mmc at ambient pressure. A pressure-induced structural phase transition from hexagonal structure to the tetragonal structure is observed in TiCr2at 443.3 GPa and in TiMn2hexagonal structure to orthorhombic structure is at 295.05 GPa. The electronic structure shows that TiX2(X = Cr, Mn) alloys are metallic in nature at all pressures. The magnetic property of nonmagnetic TiX2(X = Cr, Mn) alloys are analyzed by doping with ferromagnetic materials (Fe, Co and Ni) using the stoichiometries of TiX[Formula: see text]Y[Formula: see text] (X = Cr, Mn; Y = Fe, Co and Ni; z = 0.5,1,1.5). It is seen that the magnetic moment is induced by the substitution of ferromagnetic materials with TiX2alloys.

Structural, elastic, magnetic and electronic properties of Ti-based Heusler alloys

2020 ◽  
Vol 34 (07) ◽  
pp. 2050055 ◽  
Author(s):  
R. Murugeswari ◽  
M. Manikandan ◽  
R. Rajeswarapalanichamy ◽  
A. Milton Franklin Benial
Keyword(s):  
Electronic Properties ◽  
Density Functional ◽  
Energy Gap ◽  
Ambient Pressure ◽  
Magnetic Moments ◽  
Heusler Alloys ◽  
Text Structure ◽  
Simulation Code ◽  
Text Type ◽  
Lattice Constants

The structural, elastic, magnetic and electronic properties of titanium-based alloys [Formula: see text] [Formula: see text], [Formula: see text] and [Formula: see text] are investigated by the first-principles calculations based on density functional theory using the Vienna ab-initio simulation code. The lattice constants of [Formula: see text] [Formula: see text], [Formula: see text] and [Formula: see text] alloys are optimized for the two possible structures such as [Formula: see text] and [Formula: see text]. It is found that at ambient pressure [Formula: see text] [Formula: see text], [Formula: see text] and [Formula: see text] alloys are stable in [Formula: see text]-type crystal structure. The total magnetic moments [Formula: see text] and the energy gap [Formula: see text] of [Formula: see text] [Formula: see text], [Formula: see text] and [Formula: see text] alloys are calculated for various pressures. The total magnetic moments of [Formula: see text] [Formula: see text], [Formula: see text] and [Formula: see text] alloys in [Formula: see text] structure follow the rule [Formula: see text] and agree with the Slater–Pauling (SP) curve quite well. In both structures [Formula: see text] and [Formula: see text], the calculated magnetic moment of [Formula: see text] [Formula: see text], [Formula: see text] and [Formula: see text] alloys decreases with increase in pressure. Density of states shows the metallic nature of [Formula: see text] [Formula: see text], [Formula: see text] and [Formula: see text] alloys in [Formula: see text] structure and half-metallic [Formula: see text] behavior in [Formula: see text] structure, i.e., majority spin channel is strongly metallic and the minority spin maintains the gap at the Fermi level at the equilibrium lattice constant.

scholarly journals Theoretical Investigations of Structural Phase Transitions and Magnetic, Electronic and Thermal Properties of DyNi: Under High Pressures and Temperatures

2014 ◽  
Vol 2014 ◽  
pp. 1-7
Author(s):  
Pooja Rana ◽  
U. P. Verma
Keyword(s):  
Thermal Properties ◽  
Rare Earth ◽  
Bulk Modulus ◽  
Density Functional ◽  
High Pressures ◽  
Magnetic Moments ◽  
Structural Phase ◽  
Rare Earth Ions ◽  
Full Potential ◽  
Electronic Band

Present work is influenced by the requirement of investigation of rare earth intermetallics due to the nonavailability of theoretical details and least information from experimental results. An attempt has been made to analyse the structural, electronic, magnetic and thermal properties of DyNi using full potential linear augmented plane wave method based on density functional theory. DyNi differs from other members of lanthanides nickelates as in ground state it crystallizes in FeB phase rather than orthorhombic CrB structure. The equilibrium lattice constant, bulk modulus, and pressure derivative of bulk modulus are presented in four polymorphs (FeB, CrB, CsCl and NaCl) of DyNi. At equilibrium the cell volume of DyNi for FeB structure has been calculated as 1098.16 Bohr3 which is comparable well with the experimental value 1074.75 Bohr3. The electronic band structure has been presented for FeB phase. The results for thermal properties, namely, thermal expansion coefficient, Gruneisen parameter, specific heat and Debye temperature at higher pressure and temperatures have been reported. The magnetic moments at equilibrium lattice constants have also been tabulated as the rare earth ions associated with large magnetic moments increase their utility in industrial field for the fabrication of electronic devices due to their magnetocaloric effect used in magnetic refrigeration.

First-Principle Study on the Structural Phase Transition, and Electronic Structures of Cobalt under Pressure

2015 ◽  
Vol 729 ◽  
pp. 15-20
Author(s):  
Hong Bo Zhu ◽  
Dun Qiang Tan ◽  
Zhi Huang Xiong
Keyword(s):  
Phase Transition ◽  
Electronic Structures ◽  
Density Functional ◽  
Structural Parameters ◽  
Structural Phase ◽  
First Principles Calculation ◽  
Functional Theory ◽  
Calculated Equilibrium ◽  
Theoretical Results ◽  
Good Agreement

The structural phase transitions and electronic structures of Co are investigated by using the first-principles calculation based on density-functional theory (DFT). Our calculated equilibrium structural parameters of Co are in good agreement with the available experimental data and other theoretical results. The calculated phase transition hcp-Co → fcc-Co at ca. 125.25 GPa. The magnetic moment of hcp-Co and fcc-Co drops to zero at 155 GPa and 77 GPa, respectively.

High Pressure Structural and Mechanical Properties of YBi and ScBi Compounds

2016 ◽  
Vol 1141 ◽  
pp. 39-43 ◽  
Author(s):  
Ashok K. Ahirwar ◽  
Mahendra Aynyas ◽  
Yeshvir Singh Panwar ◽  
Sankar P. Sanyal
Keyword(s):  
Phase Transition ◽  
Theoretical Study ◽  
Structural Phase ◽  
Theoretical Data ◽  
Second Order ◽  
Mechanical And Thermal Properties ◽  
First Order ◽  
Debye Temperatures ◽  
Phase Transition Pressure ◽  
Good Agreement

A theoretical study of first order pressure induced structural phase transition, mechanical and thermal properties of YBi and ScBi compounds have been investigated using the modified inter-ionic potential theory (MIPT), which parametrically includes the effect of coulomb screening. The calculated results of phase transition pressure of ScBi and YBi are agree well with the available theoretical data. We have also reported the second order elastic constants and Debye temperature of these compounds. Our calculated values of second order elastic constant C11, C12 and C44 are 128.4, 29.5, 30.2 GPa and 123.1, 29.7, 30.3 GPa for ScBi and YBi compounds respectively. These results are in good agreement with available theoretical data. We have also estimated Debye temperatures (θD) are 80K, 86K, for ScBi and YBi compounds respectively.

High Pressure Properties of Superconducting Material Palladium

2013 ◽  
Vol 813 ◽  
pp. 327-331
Author(s):  
Wei Min Peng ◽  
Zhong Li Liu ◽  
Hong Zhi Fu
Keyword(s):  
High Pressure ◽  
Perturbation Theory ◽  
Transition Temperature ◽  
Superconducting Transition Temperature ◽  
Density Functional ◽  
High Pressures ◽  
Ambient Pressure ◽  
Superconducting Transition ◽  
Superconducting Properties ◽  
Density Functional Perturbation Theory

The electronic and the superconducting properties of Pd were studied in the framework of density functional perturbation theory. We explored the superconducting transition temperature for bulk Pd and predicted possible superconductivity at ambient and high pressures. It is found that of Pd is 0.0356 K at ambient pressure and it decreases with pressure.

Does Osmium Carbide Exist? Ab initio Investigation

2006 ◽  
Vol 987 ◽  
Author(s):  
M. Zemzemi ◽  
M. Hebbache ◽  
D. Zivkovic ◽  
L Stuparevic
Keyword(s):  
Mechanical Properties ◽  
Density Functional Theory ◽  
Transition Metals ◽  
Ab Initio ◽  
Density Functional ◽  
Ambient Pressure ◽  
Hexagonal Structure ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Good Agreement

AbstractTransition metals of the platinum group (Os, Ir, Pt, Ru, Re, Rh) do not form carbides and nitrides at ambient pressure. Osmium carbide seems to have been synthesized at zero pressure by Kempter and Nadler forty six years ago. According to the authors, OsC crystallizes in WC-type structure and has a hardness equal to 2000 kg mm-2. Up to date, no other experimental confirmation is available. We studied the electronic and mechanical properties of this hypothetical carbide using an approach based on the density-functional theory. We found that the work of the above mentioned authors is sound. The calculated lattice parameters are in good agreement with that given by those authors and a rough estimate also showed that the hardness given by them is reasonable. However, we found that the hexagonal structure of osmium carbide is electronically and mechanically unstable.

Structural Phase Transition and Electronic Properties of MgCe under High Pressure from First-Principles Calculations

2014 ◽  
Vol 577 ◽  
pp. 102-107
Author(s):  
Qiu Xiang Liu ◽  
De Ping Lu ◽  
Rui Jun Zhang ◽  
Lei Lu ◽  
Shi Fang Xie
Keyword(s):  
Phase Transition ◽  
Ground State ◽  
First Principles ◽  
Electronic Structures ◽  
Density Functional ◽  
High Pressures ◽  
Local Density ◽  
Structural Phase ◽  
First Principles Calculations ◽  
Functional Theory

The structural stability of MgCe under high pressures has been investigated by using the first-principles plane-wave pseudopotential density functional theory within the local density approximation (LDA). The obtained results predict that MgCe in the Ba structure is predicted to be the most stable structure corresponding to the ground state, because of lowest total energy. MgCe undergoes a pressure-induced phase transition from the Ba structure to B32 structure at 36 GPa. And no further transition is found up to 120 GPa. In addition, the electronic structures of four structures of MgCe are also calculated and discussed.

scholarly journals Structural and Transport Properties of 1T-VSe2 Single Crystal Under High Pressures

2021 ◽  
Vol 8 ◽  
Author(s):  
Dongqi Song ◽  
Ying Zhou ◽  
Min Zhang ◽  
Xinyi He ◽  
Xinjian Li
Keyword(s):  
Transition Metal ◽  
Transport Properties ◽  
Electrical Transport ◽  
Critical Pressure ◽  
High Pressures ◽  
Ambient Pressure ◽  
Structural Phase ◽  
Density Wave ◽  
Transition Metal Dichalcogenides ◽  
Transition Metal Dichalcogenide

Two-dimensional transition metal dichalcogenide 1T-VSe2 exhibits a unique three-dimensional charge density wave (CDW) order below ∼110 K at ambient pressure, which shows unusual evolution under pressure. Here we report on the high-pressure structural and transport properties of 1T-VSe2 by extending the pressure up to 57.8 GPa, through electrical transport, synchrotron X-ray diffraction (XRD) and Raman scattering measurements, which unravel two critical pressure points. The CDW transition is found to be enhanced under compression at a rate of 16.5 K/GPa up to the first critical pressure PC1 ∼ 12 GPa, at which a structural phase transition from hexagonal P-3m1 to monoclinic C2/m phase takes place. The second critical pressure PC2 ∼ 33 GPa corresponds to another structural transition from monoclinic C2/m to P21/m phase. These findings extend the phase diagram of pressurized 1T-VSe2 and may help to understand pressure tuning of structures in transition metal dichalcogenides.

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