Pressure-induced phase transition and thermophysical properties of cubic refractory metal nitrides: theory

2013 ◽  
Vol 91 (1) ◽  
pp. 27-33 ◽  
Author(s):  
Anurag Srivastava ◽  
Bhoopendra Dhar Diwan
Keyword(s):  
Phase Transition ◽  
Thermophysical Properties ◽  
Refractory Metal ◽  
Body Force ◽  
Structural Phase ◽  
Metal Nitrides ◽  
Type Phase ◽  
Three Body ◽  
First Time ◽  
Force Potential

The present paper reports the structural stability, pressure-induced phase transition, and thermophysical properties for refractory metal nitrides (viz: TiN, ZrN, HfN, VN, NbN, and TaN) computed using a three-body force potential model. The structural phase transitions from a parental NaCl (B1) type phase to the most stable CsCl (B2) type phase has been observed in the pressure range 162–370 GPa. Study includes the computation of thermophysical properties (U, f, θD, υ0,γ, β, αV/CV), where some of the properties are being reported for the first time on these materials.

Structural phase transition of refractory metal carbides at high pressure

2014 ◽  
Vol 92 (5) ◽  
pp. 415-419 ◽  
Author(s):  
Bhoopendra Dhar Diwan
Keyword(s):  
Phase Transition ◽  
Structural Properties ◽  
Structural Phase Transition ◽  
Refractory Metal ◽  
Structural Phase ◽  
Metal Carbides ◽  
Type Phase ◽  
Reported Data ◽  
Three Body ◽  
Force Potential

There has been significant concern in analyzing the structural stability, structural properties, and pressure-induced structural phase transition of refractory metal carbides, RC (R = Ti, Zr, Hf, V, Nb, and Ta), by using the three-body force potential model calculation modified approach. The more accurate description of the interionic spacing (r0) suggests that the interactions considered in the present computation are capable of correctly predicting the structural properties of these materials. In the preset paper, we have investigated the relative stability of the two competitive phases of metal carbides and discussed the possible phase transitions from its parental NaCl (B1) type phase to its most stable CsCl (B2) type phase in the pressure range 344–572 GPa. The computed interionic spacing (r0) and phase transition pressures (PT) are in reasonable agreement with the other reported data.

scholarly journals Структура и динамика решетки MeF-=SUB=-2-=/SUB=- (Me=Ca, Sr, Ba, Pb) в кубической и орто-фазах: ab initio расчет

2019 ◽  
Vol 61 (1) ◽  
pp. 137
Author(s):  
В.А. Чернышев ◽  
В.С. Рюмшин ◽  
П.А. Агзамова
Keyword(s):  
Crystal Structure ◽  
Phase Transition ◽  
Elastic Constants ◽  
Periodic Structures ◽  
Structural Phase ◽  
Orthorhombic Phase ◽  
Hartree Fock ◽  
Few Data ◽  
First Time ◽  
Ir And Raman

AbstractThe MF_2 (M = Ca, Sr, Ba, Pb) crystals undergo a structural phase transition from the cubic to the orthorhombic phase in a range of 1–10 GPa. Although the cubic fluorites are well studied experimentally, there has been almost no information on their orthorhombic phase to date. Despite a few data on the Raman spectra available in the literature, there is still a lack of IR spectra of these structures. In this respect, this work aims to study the crystal structure and the phonon spectrum of MF_2 crystals (M = Ca, Sr, Ba, Pb) in both the cubic and orthorhombic phases, using the MO LKAO approach with hybrid DFT functionals that take the contribution of nonlocal exchange in the Hartree—Fock formalism into account. The frequencies and types of fundamental IR and Raman vibrations, as well as the frequencies of “silent” modes, are found. The calculations of elastic constants for the orthorombic phase have been performed at the first time. The program CRYSTAL14 intended for simulation of periodic structures within the MO LKAO approach was used for the calculations.

scholarly journals Generation of long range and short range potentials

2021 ◽  
Author(s):  
Shinsho Oryu
Keyword(s):  
Long Range ◽  
Short Range ◽  
Body Force ◽  
Molecular System ◽  
Mass Dependence ◽  
Particle Transfer ◽  
Three Body ◽  
Force Potential ◽  
Type Potential

Abstract The general particle transfer (GPT) potential generates not only the Yukawa-type potential but also the 1⁄r^n-type potential in the hadron system, where the mass dependence of the transferred particle is clarified. The GPT potential from the atom-molecular system to the quark-gluon system was transversally studied, where the pico-meter physics could be highlighted. It was found that the long range three-body Efimov potential is connected with the short range three-body force potential.

Structural and elastic behavior of aluminum pnictides with temperature effect

2019 ◽  
Vol 33 (30) ◽  
pp. 1950365
Author(s):  
Pooja Pawar ◽  
Sadhna Singh
Keyword(s):  
Phase Transition ◽  
Temperature Effect ◽  
Thermophysical Properties ◽  
Potential Model ◽  
Theoretical Data ◽  
Elastic Behavior ◽  
Single Model ◽  
Realistic Interaction ◽  
Reported Data ◽  
First Time

A realistic interaction potential model (RIPM) has been formulated to theoretically predict the pressure-induced phase transition, elastic properties and thermophysical properties of AlAs and AlSb, including temperature effect (300 K). This model exhibits a better agreement with the available experimental rather than theoretical data for obtained calculations of phase transition pressures and volume collapses. We have achieved elastic moduli, anisotropy factor, Poisson’s ratio, Kleinman parameter, on the basis of the calculated elastic constants. Apparently, this is the first time when thermophysical properties of these compounds are explored at temperature effect by using a single model. Our results are justified by available measured and other reported data which support the validity of our model.

Search for Pnma materials with high-temperature structural phase transitions

1999 ◽  
Vol 55 (2) ◽  
pp. 177-185 ◽  
Author(s):  
J. M. Igartua ◽  
M. I. Aroyo ◽  
E. Kroumova ◽  
J. M. Perez-Mato
Keyword(s):  
Crystal Structure ◽  
Phase Transition ◽  
High Temperature ◽  
Structural Phase ◽  
Atomic Displacement ◽  
Inorganic Crystal Structure Database ◽  
Higher Symmetry ◽  
Type Phase ◽  
Higher Temperature ◽  
Crystal Structure Database

A systematic search for structures having a high-temperature structural phase transition can be carried out through the identification in the structural databases of those structures that can be considered pseudosymmetric. Pseudosymmetry in a crystal structure indicates the possibility of a similar configuration of higher symmetry. If the distortion relating both structures is small enough, it can be expected that the crystal acquires the more symmetric configuration through a Landau-type phase transition at a higher temperature. Here, we present the results of such a search among inorganic structures with space group Pnma retrieved from the Inorganic Crystal Structure Database. Pseudosymmetry has indeed been detected in those compounds with a known (displacive) Landau-type phase transition at higher temperatures. This is measured by a parameter Δ, which measures the maximal atomic displacement relating the pseudosymmetry-transformed structure and the original one. In most of these compounds with a known phase transition, this parameter was smaller than 1.0 Å for at least one minimal supergroup of Pnma. The database contains 144 additional structures with pseudosymmetry features under the same quantitative limit. A comparison of the Δ distributions in both sets of compounds suggests a smaller Δ window (with 0.7 Å as maximal value) for selecting the materials having maximal probability of exhibiting a phase transition at higher temperatures. A set of 58 compounds fulfils this criterion.

Structural and elastic properties of barium chalcogenides (BaX, X=O, Se, Te) under high pressure

Open Physics ◽  
2008 ◽  
Vol 6 (2) ◽  
Author(s):  
Purvee Bhardwaj ◽  
Sadhna Singh ◽  
Neeraj Gaur
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Elastic Constants ◽  
Structural Phase ◽  
Transition Pressure ◽  
Phase Transition Pressure ◽  
Cscl Structure ◽  
Three Body ◽  
Derivatives Of ◽  
Good Agreement

AbstractIn the present paper we have investigated the high-pressure, structural phase transition of Barium chalcogenides (BaO, BaSe and BaTe) using a three-body interaction potential (MTBIP) approach, modified by incorporating covalency effects. Phase transition pressures are associated with a sudden collapse in volume. The phase transition pressures and associated volume collapses obtained from TBIP show a reasonably good agreement with experimental data. Here, the transition pressure, NaCl-CsCl structure increases with decreasing cation-to-anion radii ratio. In addition, the elastic constants and their combinations with pressure are also reported. It is found that TBP incorporating a covalency effect may predict the phase transition pressure, the elastic constants and the pressure derivatives of other chalcogenides as well.

LOW TEMPERATURE SPECIFIC HEAT OF (KBr)1-x(KCN)x MIXED CRYSTAL

2003 ◽  
Vol 17 (26) ◽  
pp. 1391-1398 ◽  
Author(s):  
N. K. GAUR ◽  
NUPINDER KAUR ◽  
MANIK MANAKE ◽  
JYOTSNA GALGALE ◽  
R. K. SINGH
Keyword(s):  
Experimental Data ◽  
Thermal Properties ◽  
Specific Heat ◽  
Mixed Crystal ◽  
Body Force ◽  
Molecular Force ◽  
Low Temperature Specific Heat ◽  
Three Body ◽  
First Time ◽  
Good Agreement

We have investigated the cohesive and thermodynamic properties of ( KBr )1-x( KCN )x using an extended three-body force shell model (ETSM), which has been found to be adequately suitable for the description of orientationally disordered mixed cyanide-halide crystals. The specific heat of ( KBr )1-x( KCN )x for compositions (x=0.53, 0.65, 0.73, 0.84 and 0.93) at temperature 10 K ≤T≤150 K have been computed using the ETSM for the first time. The paper also reports the calculated results on Debye temperature (Θ D ), cohesive energy (Φ), compressibility (β), molecular force constant (f) and Restrahlen frequency (ν0) of ( KBr )1-x( KCN )x. The results on specific heat and some other thermal properties are in good agreement with their available experimental data.

scholarly journals Investigation of Structural Phase Transition of PbS

2012 ◽  
Vol 2012 ◽  
pp. 1-4 ◽  
Author(s):  
Purvee Bhardwaj
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Elastic Properties ◽  
Structural Phase Transition ◽  
Structural Phase ◽  
Three Body ◽  
Body Potential ◽  
Model Phase ◽  
Sudden Collapse ◽  
Good Agreement

The high-pressure structural phase transition of semiconductor PbS has been investigated, using the three body potential (TBP) model. Phase transition pressures are associated with a sudden collapse in volume. The phase transition pressures and related volume collapses obtained from this model show a generally good agreement with available results. Moreover, the elastic properties of PbS are also investigated.

scholarly journals Structural phase transition and bonding properties of high-pressure polymeric CaN3

RSC Advances ◽  
2018 ◽  
Vol 8 (8) ◽  
pp. 4314-4320 ◽  
Author(s):  
Pugeng Hou ◽  
Lili Lian ◽  
Yongmao Cai ◽  
Bao Liu ◽  
Bo Wang ◽  
...  
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Structural Phase Transition ◽  
Structural Phase ◽  
Low Pressure ◽  
Bonding Properties ◽  
First Time

Two new monoclinic P1̄-CaN3 and C2/m-CaN3 are predicted to become energetically stable under low pressure. For the first time, we identify one novel phase featuring charged “N6” chain in the P1̄-CaN3 structure.

Sign in / Sign up

Export Citation Format

Share Document