Thermomechanical, electronic and thermodynamic properties of ZnS cubic polymorphs: an ab initio investigation on the zinc-blende–rock-salt phase transition

2019 ◽  
Vol 75 (6) ◽  
pp. 1042-1059 ◽  
Author(s):  
Gianfranco Ulian ◽  
Giovanni Valdrè
Keyword(s):  
Phase Transition ◽  
Thermodynamic Properties ◽  
Ab Initio ◽  
Zinc Sulfide ◽  
Rock Salt ◽  
Electronic Band ◽  
Zinc Blende ◽  
Wide Range ◽  
Static Conditions ◽  
First Time

In the present work, an extensive and detailed theoretical investigation is reported on the thermomechanical, electronic and thermodynamic properties of zinc-blende (sphalerite, zb-ZnS) and rock-salt zinc sulfide (rs-ZnS) over a wide range of pressure, by means of ab initio Density Functional Theory, Gaussian type orbitals and the well known B3LYP functional. For the first time, vibrational frequencies, phonon dispersion relations, elasto-piezo-dielectric tensor, thermodynamic and thermomechanical properties of rs-ZnS were calculated with a consistent approach that allows a direct comparison with the low-pressure polymorph. Special attention was paid to the evaluation of the thermodynamic pressure–temperature stability of the mineral phases between 0–25 GPa and 0–800 K. The static (T = 0 K) bulk moduli of sphalerite and rock-salt ZnS were 72.63 (3) GPa and 84.39 (5) GPa, respectively. The phase transition in static conditions calculated from the equation of state was about 15.5 GPa, whereas the elastic constants data resulted in P trans = 14.6 GPa. At room temperature (300 K), the zb-rs transition occurs at 14.70 GPa and a negative Clapeyron slope (dP)/(dT) = 0.0023 was observed up to 800 K. The electronic band structure showed a direct band gap for zb-ZnS (E g = 4.830 eV at equilibrium geometry), which became an indirect one by increasing pressure above 11 GPa. The results were found to be in good agreement with the available experimental and theoretical data, further extending the knowledge of important properties of zinc sulfide, in particular the thermomechanical ones of the rock-salt polymorph here extensively explored for the first time.

scholarly journals First-Principle Study of Zinc Sulfide (Zinc Blende, Rock Salt and Wurtzite): Stability, Phase Transition and Structural Parameters

2020 ◽  
pp. 313-318
Author(s):  
Ibrahim Isah ◽  
Mustapha Isah
Keyword(s):  
Phase Transition ◽  
Zinc Sulfide ◽  
Rock Salt ◽  
Density Functional ◽  
Structural Parameters ◽  
First Principle ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Zinc Blende ◽  
The Stability

The research investigates the stability, phase transition and structural parameters of zinc sulfide (Zinc blende, Rock salt and Wurtzite) using first-principle. The study employs generalized gradient approximation (GGA) within density functional theory (DFT) in which ultra-soft pseudopotential (Zn.pbe-van.UPFb and S.pbe-van_bm.UPFc ) were used for both zinc and sulfide respectively. Self-consistent calculation was made using cut-off energies of 26Ry (~350 eV) and 180 Ry (~2450eV) for the cut-off wave function within the convergence accuracy of ~1mRy with respect to total energy and 0.5kbar in case of pressure. The results obtained show that Wurtzite is more stable because it has lowest energy among the three structures, there is transition from zinc blende to rock salt and from Wurtzite to rock salt with transition pressures of 17.5GPa and 16.9GPa respectively and all the three polymorphs are semi-conductors due to their band gap.

scholarly journals Heat Capacities and Thermodynamic Properties of Hungchaoite and Mcallisterite

Molecules ◽  
2019 ◽  
Vol 24 (24) ◽  
pp. 4470
Author(s):  
Jiangtao Song ◽  
Fei Yuan ◽  
Long Li ◽  
Yafei Guo ◽  
Tianlong Deng
Keyword(s):  
Phase Transition ◽  
Thermodynamic Properties ◽  
Thermodynamic Functions ◽  
Process Design ◽  
Chemical Engineering ◽  
Heat Capacities ◽  
Salt Lakes ◽  
Engineering Process ◽  
Thermal Anomalies ◽  
First Time

The heat capacities on two minerals of hungchaoite (MgB4O7·9H2O, Hu) and mcallisterite (MgB6O10·7.5H2O, Mc) have been measured with a precision calorimeter at temperatures ranging from 306.15 to 355.15 K, experimentally. It was found that there are no phase transition and thermal anomalies, and the molar heat capacities against temperature for the minerals of hungchaoite and mcallisterite were fitted as C p , m , Hu   =   − 27019.23675 + 229.55286 T   −   0.63912 T   2   +   ( 5.95862   ×   10   − 4 )   T   3 and C p , mMc   =   − 9981.88552   +   84.10964 T   −   0.22685 T   2   +   ( 2.0593   ×   10   − 4 )   T   3 , respectively. The molar heat capacities and thermodynamic functions of (HT-H298.15), (ST-S298.15), and (GT-G298.15) at intervals of 1 K for the two minerals were obtained for the first time. These results are significant in order to understand the thermodynamic properties of those minerals existing in nature salt lakes, as well as applying them to the chemical engineering process design.

A detailed first principle study on the structural, elastic, and electronic properties of indium arsenide (InAs) under induced pressure

2016 ◽  
Vol 94 (3) ◽  
pp. 254-261
Author(s):  
Kh. Kabita ◽  
M. Jameson ◽  
B.I. Sharma ◽  
R.K. Brojen ◽  
R.K. Thapa
Keyword(s):  
Electronic Properties ◽  
Indium Arsenide ◽  
Rock Salt ◽  
Density Functional ◽  
Structural Phase ◽  
Theoretical Data ◽  
Partial Density ◽  
Electronic Band ◽  
Zinc Blende ◽  
Salt Structure

An ab initio calculation of the structural, elastic, and electronic properties of indium arsenide (InAs) under induced pressure is investigated using density functional theory with modified Becke–Johnson potential within the generalised gradient approximation of the Perdew–Burke–Ernzerhof scheme. The lattice parameters are found to be in good agreement with experimental and other theoretical data. The pressure-induced structural phase transition of InAs zinc blende to rock salt structure is found to occur at 4.7 GPa pressure with a 17.2% of volume collapse. The elastic properties of both the zinc blende and rock salt structures at different pressures are studied. The electronic band structures at different pressures for both the structures are investigated using the total and partial density of states. The energy band gap of the InAs zinc blende phase is increased with increasing pressure while in rock salt the phase the conduction band crosses towards the valence band and thus shows metallic behaviour.

LEAD-CHALCOGENIDES UNDER PRESSURE: AB-INITIO STUDY

2013 ◽  
Vol 22 ◽  
pp. 612-618 ◽  
Author(s):  
DINESH C. GUPTA ◽  
IDRIS HAMID
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Ab Initio ◽  
Band Gap ◽  
Rock Salt ◽  
High Pressures ◽  
Ambient Pressure ◽  
High Pressure Phase ◽  
Lead Chalcogenides ◽  
Pressure Phase

ab-initio calculations using fully relativistic pseudo-potential have been performed to investigate the high pressure phase transition, elastic and electronic properties of lead-chalcogenides including the less known lead polonium. The calculated ground state parameters, for the rock-salt structure show good agreement with the experimental data. The enthalpy calculations show that these materials undergo a first-order phase transition from rock-salt to CsCl structure at 19.4, 15.5, 11.5 and 7.3 GPa for PbS, PbSe, PbTe and PbPo, respectively. Present calculations successfully predicted the location of the band gap at L-point of Brillouin zone as well as the value of the band gap in every case at ambient pressure. It is observed that unlike other lead-chalcogenides, PbPo is semi-metal at ambient pressure. The pressure variation of the energy gap indicates that these materials metalized under high pressures. For this purpose, the electronic structure of these materials has also been computed in parent as well as in high pressure phase.

Phase transition in SiC from zinc-blende to rock-salt structure and implications for carbon-rich extrasolar planets

2017 ◽  
Vol 102 (11) ◽  
pp. 2230-2234 ◽  
Author(s):  
Yuto Kidokoro ◽  
Koichiro Umemoto ◽  
Kei Hirose ◽  
Yasuo Ohishi
Keyword(s):  
Phase Transition ◽  
Rock Salt ◽  
Extrasolar Planets ◽  
Rock Salt Structure ◽  
Zinc Blende ◽  
Salt Structure

PRESSURE-INDUCED METALLIZATION AND SUPERCONDUCTIVITY IN InP AND InN

2011 ◽  
Vol 25 (04) ◽  
pp. 573-587
Author(s):  
K. IYAKUTTI ◽  
V. REJILA ◽  
M. RAJARAJESWARI ◽  
C. NIRMALA LOUIS ◽  
S. MAHALAKSHMI
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Structural Phase Transition ◽  
Electronic Band Structure ◽  
Indium Nitride ◽  
Structural Phase ◽  
Superconducting Transition ◽  
Electronic Band ◽  
Zinc Blende ◽  
Lmto Method

The electronic band structure, structural phase transition, metallization and superconducting transition of cubic zinc blende-type indium phosphide ( InP ) and indium nitride ( InN ), under pressure, are studied using TB-LMTO method. These indium compounds become metals and superconductors under high pressure but before that they undergo structural phase transition from ZnS to NaCl structure. The ground-state properties and band gap values are compared with the experimental and previous theoretical results. From our analysis, it is found that the metallization pressure increases with increase of lattice constant. The superconducting transition temperatures (Tc) of InP and InN are obtained as a function of pressure for both the ZnS and NaCl structures and these compounds are identified as pressure-induced superconductors. When pressure is increased Tc increases in both the normal ( ZnS ) and high pressure ( NaCl ) structures. The dependence of Tc on electron–phonon mass enhancement factor λ shows that InP and InN are electron–phonon mediated superconductors. The non-occurrence of metallization, phase transition and onset of superconductivity simultaneously in InP and InN are confirmed.

scholarly journals Subpicosecond metamagnetic phase transition driven by non-equilibrium electron dynamics

2021 ◽  
Author(s):  
Federico Pressacco ◽  
Davide Sangalli ◽  
Vojtěch Uhlíř ◽  
Dmytro Kutnyakhov ◽  
Jon Ander Arregi ◽  
...  
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Ab Initio ◽  
Photoelectron Spectroscopy ◽  
Electronic Band Structure ◽  
Ferromagnetic Phase ◽  
Electron Dynamics ◽  
Electronic Band ◽  
Time Resolved ◽  
Non Equilibrium

Abstract Femtosecond light-induced phase transitions between different macroscopic orders provide the possibility to tune the functional properties of condensed matter on ultrafast timescales. In first-order phase transitions, transient non-equilibrium phases and inherent phase coexistence often preclude non-ambiguous detection of transition precursors and their temporal onset. Here, we present a study combining time-resolved photoelectron spectroscopy and ab-initio electron dynamics calculations elucidating the transient subpicosecond processes governing the photoinduced generation of ferromagnetic order in antiferromagnetic FeRh. The transient photoemission spectra are accounted for by assuming that not only the occupation of electronic states is modified during the photoexcitation process. Instead, the photo-generated non-thermal distribution of electrons modifies the electronic band structure. The ferromagnetic phase of FeRh, characterized by a minority band near the Fermi energy, is established 350 ± 30 fs after the laser excitation. Ab-initio calculations indicate that the phase transition is initiated by a photoinduced Rh-to-Fe charge transfer.

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