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.

STRUCTURAL PHASE TRANSITION IN BORON COMPOUNDS AT HIGH PRESSURE

2010 ◽  
Vol 24 (10) ◽  
pp. 1235-1244 ◽  
Author(s):  
MINA TALATI ◽  
PRAFULLA K. JHA
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Elastic Constants ◽  
Structural Phase ◽  
Boron Compounds ◽  
Potential Approach ◽  
Transition Pressure ◽  
Zinc Blende ◽  
Phase Transition Pressure ◽  
Good Agreement

The high-pressure induced structural phase transitions and pressure induced elastic and anharmonic behavior of boron compounds viz. BN, BP, and BAs have been investigated using an inter-ionic potential approach based on charge transfer effect. These compounds go to NaCl phase (B1) under pressure from zinc blende phase (B3). The variations of second-order elastic constants and their combinations follow a systematic trend with pressure, identical to that observed in other compounds of zinc blende structure family. Shear stiffness constants decrease with increasing pressure up to phase transition pressure. The bulk moduli of these compounds are in reasonably good agreement with other theoretical and experimental data. The values of phase transition pressure of these compounds obtained by using the present approach are also in good agreement with those predicted by using the pseudo potential approach. The present approach has also succeeded in predicting the Born and relative stability criterion for stable zinc blende phase of these compounds. We also present a set of third-order elastic constants and pressure derivatives of second-order elastic constants for boron compounds.

Structural Phase Stability of ThSb Under Pressure

1994 ◽  
Vol 364 ◽  
Author(s):  
B. Palanivel ◽  
G. Kalpana ◽  
M. Rajagopalan
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Cell Volume ◽  
Structural Transition ◽  
Structural Phase ◽  
Tight Binding ◽  
Lmto Method ◽  
Cscl Structure ◽  
Total Energies ◽  
Good Agreement

AbstractThe electronic structure and high pressure structural phase transition in thorium antimonide have been investigated using the tight binding LMTO method. We have calculated the total energies by reducing the cell volume for NaCl as well as CsCl structures using TBLMTO method. The total energy calculations reveal that ThSb undergoes a structural transition from NaCl to CsCl structure at 78 kbar. The calculated value of equilibrium cell volume and the cell volume at which phase transition occurs are found to have a good agreement with the experimental results.

Phase transition in CeSe, EuSe and LaSe under high pressure

Open Physics ◽  
2007 ◽  
Vol 5 (4) ◽  
Author(s):  
Sadhna Singh ◽  
R. Singh ◽  
Atul Gour
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Elastic Behavior ◽  
Transition Pressure ◽  
High Pressure Phase Transition ◽  
Phase Transition Pressure ◽  
Volume Collapse ◽  
Range Overlap ◽  
Three Body ◽  
Repulsive Forces

AbstractThe high pressure phase transition and elastic behavior of rare earth monoselenides (CeSe, EuSe and LaSe) which crystallize in a NaCl-structure have been investigated using the three body interaction potential (TBIP) approach. These interactions arise due to the electronshell deformation of the overlapping ions in crystals. The TBP model consists of a long range Coulomb, three body interactions and the short range overlap repulsive forces operative up to the second neighboring ions. The authors of this paper estimated the values of the phase transition pressure and the associated volume collapse to be closer than other calculations. Thus, the TBIP approach also promises to predict the phase transition pressure and pressure variations of elastic constants of lanthanide compounds.

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.

Pressure Induced Structural Phase Transition in InP at Room Temperature

2016 ◽  
Vol 28 ◽  
pp. 98-100
Author(s):  
Pooja Pawar ◽  
Shilpa Kapoor ◽  
Sadhna Singh
Keyword(s):  
Phase Transition ◽  
Structural Phase ◽  
Theoretical Data ◽  
Effect Of Temperature ◽  
Repulsive Interaction ◽  
Transition Pressure ◽  
Phase Transition Pressure ◽  
Realistic Interaction ◽  
Range Overlap ◽  
Three Body

We have investigated the pressure induced phase transition of InP from ZB to NaCl structure associated by using realistic interaction potential model (RIPM), which is modified by taking effect of temperature. This model consists of coulomb interaction, three body interaction, and short range overlap repulsive interaction up to second nearest neighbour. Phase transition pressure is associated with a sudden collapse in volume showing the incidence of first order phase transition. The phase transition pressure and associated volume collapses obtained from present model show a generally good agreement with the available experimental and theoretical data.

Study of Structural, Elastic Properties and their Pressure Dependence in IrN Compound

2016 ◽  
Vol 28 ◽  
pp. 16-22 ◽  
Author(s):  
Shubhangi Soni ◽  
Arvind Jain ◽  
Kamal Kumar Choudhary ◽  
Netram Kaurav
Keyword(s):  
Phase Transition ◽  
Theoretical Study ◽  
Structural Phase ◽  
Elastic Behavior ◽  
Interionic Interaction ◽  
First Order ◽  
Transition Pressure ◽  
Zinc Blende ◽  
Phase Transition Pressure ◽  
Cscl Structure

A theoretical study of the elastic behavior in IrN compound using effective interionic interaction potential is carried out. The estimated values of phase transition pressure and the vast volume discontinuity in pressure-volume (PV) phase diagram indicate the structural phase transition from zinc blende (B3) to CsCl structure (B2). C11, C12 and C44 increase nearly linearly with pressure. At phase transition pressure IrN has shown a discontinuity in second order elastic constants, which is in accordance with the first-order character of the phase transition.

High-Pressure Structural Phase Transition in MgxCd1-xO Compounds

2016 ◽  
Vol 28 ◽  
pp. 77-84
Author(s):  
Saligram Verma ◽  
Arvind Jain ◽  
Kamal Kumar Choudhary ◽  
Netram Kaurav
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Physical Properties ◽  
Structural Phase Transition ◽  
Structural Phase ◽  
Repulsive Interaction ◽  
Interionic Interaction ◽  
Phase Transition Pressure ◽  
Cscl Structure ◽  
Physical Interactions

The high-pressure technique is useful to understand physical properties because the technique can directly control bond length and phase transition. As a general trend, the pressure-induced phase transition causes an increase of coordination number with a drastic change of their physical properties. Here, we attempt to explore the pressure-induced phase transitions from the sixfold-coordinated NaCl structure (B1) to the eightfold-coordinated CsCl structure (B2) in MgxCd1−xO by applying an effective interionic interaction potential, which includes the long range Coulomb, van der Waals (vdW) interaction and the short-range repulsive interaction upto second-neighbor ions within the Hafemeister and Flygare approach. Assuming that both the ions are polarizable, the Slater-Kirkwood variational method is employed to estimate the vdW coefficients for parent compounds. The estimated values of the phase transition pressure (Pt) increase with Mg concentration. The vast volume discontinuity in pressure volume phase diagram identifies the structural phase transition from B1 to B2 structure. The results obtain from the present calculations requires the complete understanding of many physical interactions that are essential to ternary oxides, containing elements with size and chemical mismatch, will lead to a consistent explanation of the documented structural properties.

High Pressure Structural Phase Transition and Elastic Properties of Europium Chalcogenides

2014 ◽  
Vol 1047 ◽  
pp. 163-169
Author(s):  
Ashvini K. Sahu ◽  
M. Aynyas ◽  
R. Bhardwaj ◽  
Sankar P. Sanyal
Keyword(s):  
Experimental Data ◽  
Phase Transition ◽  
High Pressure ◽  
Elastic Properties ◽  
Structural Phase Transition ◽  
Structural Phase ◽  
Phase Transition Pressure ◽  
Ionic Nature ◽  
Three Body ◽  
Body Potential

The high pressure induced structural phase transition and elastic properties of three Europium chalcogenides (EuX; X = S, Se, Te) have been studied using a two body potential approach. The calculated compression curves of EuS, EuSe and EuTe obtained so has been compared with recently measured three body potential data. The calculated transition pressures are in good agreement with the experimental data. The phase transition pressure for EuS, EuSe and EuTe going from the NaCl phase to CsCl phase have been observed are 22 GPa, 15 GPa, 10 GPa respectively, close the theoretical and experimental data. We have also calculated bulk modulas and second order elastic constants at high pressure which show partly ionic nature of theses compounds. The B1 (NaCl) phase is found to be higher in energy than the B2 (CsCl) phase and more stable at zero pressure.

Evaluation from First Principles the Structural Stability of Mg Containing Different Amounts of Al Atoms under High Pressure

2013 ◽  
Vol 391 ◽  
pp. 56-60
Author(s):  
Qiu Xiang Liu ◽  
Rui Jun Zhang ◽  
De Ping Lu ◽  
Andrej Atrens
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Structural Stability ◽  
First Principles ◽  
Cohesive Energy ◽  
Structural Phase ◽  
Energy Calculations ◽  
Transition Pressure ◽  
Al Content ◽  
Phase Transition Pressure

The structural stability and phase transition of magnesium (Mg) containing different amounts of Al under high pressure was studied by means of first-principles total energy calculations. The cohesive energy calculations showed that the hcp and bcc structures of Mg-4.17 at%Al and Mg-8.33 at%Al were of the strong structural stability. The enthalpy for hcp and bcc structures of Mg was dependent upon the Al content. With increasing Al content from 0 to 8.33 at%, the enthalpy for hcp and bcc structures increased monotonously. Based on the enthalpy differences of the hcp and bcc structures under different pressures, the phase transition pressure under which the hcpbcc structural phase transition may take place for pure Mg, Mg-4.17 at%Al and Mg-8.33 at%Al was 60 GPa, 70 GPa and 85 GPa, respectively, indicating that with the increasing Al content, the phase transition pressure became higher and the hcpbcc transition was more difficult.

scholarly journals Role of temperature in the numerical analysis of CaO under high pressure

2010 ◽  
Vol 8 (1) ◽  
pp. 126-133 ◽  
Author(s):  
Purvee Bhardwaj ◽  
Sadhna Singh
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Numerical Analysis ◽  
Thermodynamic Properties ◽  
Elastic Constants ◽  
Volume Change ◽  
Thermodynamical Properties ◽  
Phase Transition Pressure ◽  
Different Temperatures

AbstractIn this paper we focus on the elastic and thermodynamic properties of the B1 phase of CaO by using the modified TBP model, including the role of temperature. We have successfully obtained the phase transition pressure and volume change at different temperatures. In addition elastic constants and bulk modulus of B1 phase of CaO at different temperatures are discussed. Our results are comparable with the previous ones at high temperatures and pressures. The thermodynamical properties of the B1 phase of CaO are also predicted.

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