scholarly journals Origin of pressure-induced band gap tuning in tin halide perovskites

2020 ◽  
Vol 1 (8) ◽  
pp. 2840-2845
Author(s):  
Mauro Coduri ◽  
Thomas B. Shiell ◽  
Timothy A. Strobel ◽  
Arup Mahata ◽  
Federico Cova ◽  
...  
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Band Gap ◽  
Orthorhombic Phase ◽  
Blue Shift ◽  
Red Shift ◽  
Pressure Increase ◽  
Halide Perovskites ◽  
Band Gap Tuning ◽  
High Pressure Study

Structural and optical high-pressure study of FASnBr3 revealed a cubic to orthorhombic phase transition near 1.4 GPa accompanied by a huge band gap red-shift from 2.4 to 1.6 eV, which is followed by a blue-shift of ∼0.2 eV upon further pressure increase.

scholarly journals Crystal and electronic structure engineering of tin monoxide by external pressure

2021 ◽  
Author(s):  
Kun Li ◽  
Junjie Wang ◽  
Vladislav A. Blatov ◽  
Yutong Gong ◽  
Naoto Umezawa ◽  
...  
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Band Gap ◽  
High Pressures ◽  
Low Pressure ◽  
Widespread Application ◽  
Space Group ◽  
Tin Monoxide ◽  
High Possibility ◽  
Pressure Phase

AbstractAlthough tin monoxide (SnO) is an interesting compound due to its p-type conductivity, a widespread application of SnO has been limited by its narrow band gap of 0.7 eV. In this work, we theoretically investigate the structural and electronic properties of several SnO phases under high pressures through employing van der Waals (vdW) functionals. Our calculations reveal that a metastable SnO (β-SnO), which possesses space group P21/c and a wide band gap of 1.9 eV, is more stable than α-SnO at pressures higher than 80 GPa. Moreover, a stable (space group P2/c) and a metastable (space group Pnma) phases of SnO appear at pressures higher than 120 GPa. Energy and topological analyses show that P2/c-SnO has a high possibility to directly transform to β-SnO at around 120 GPa. Our work also reveals that β-SnO is a necessary intermediate state between high-pressure phase Pnma-SnO and low-pressure phase α-SnO for the phase transition path Pnma-SnO →β-SnO → α-SnO. Two phase transition analyses indicate that there is a high possibility to synthesize β-SnO under high-pressure conditions and have it remain stable under normal pressure. Finally, our study reveals that the conductive property of β-SnO can be engineered in a low-pressure range (0–9 GPa) through a semiconductor-to-metal transition, while maintaining transparency in the visible light range.

scholarly journals High-pressure study of the magnetic phase transition in MnSi

2009 ◽  
Vol 79 (10) ◽  
Author(s):  
Alla E. Petrova ◽  
Vladimir N. Krasnorussky ◽  
T. A. Lograsso ◽  
Sergei M. Stishov
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Magnetic Phase Transition ◽  
Magnetic Phase ◽  
High Pressure Study

scholarly journals Phase Transition and Polymerization of Acetonitrile under High Pressure

2014 ◽  
Vol 70 (a1) ◽  
pp. C763-C763
Author(s):  
Haiyan Zheng ◽  
Kuo Li ◽  
George Cody ◽  
Chris Tulk ◽  
Jamie Molaison ◽  
...  
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Reaction Mechanism ◽  
Neutron Diffraction ◽  
Raman Spectra ◽  
Hydrogen Transfer ◽  
Layer Structure ◽  
Van Der Waals ◽  
Orthorhombic Phase ◽  
Organic Polymer

Successful application of high pressure on synthesis of organic polymer, including the conducting polymer and super hard materials depends on the knowledge of reaction mechanism. The evolution of crystal structure under high pressure especially the structure close to transition pressure is crucial to conclude the reaction mechanism. Nitriles represent a large class of interstellar molecules and are the potential source of amino acids. Understanding its behavior at extreme conditions has gained increasing attention recently. Acetonitrile (CH3CN), the simplest organic compound with C≡N triple bond, can act as a model system for studying the pressure induced polymerization. The phase transition of acetonitrile under high pressure has been studied extensively.[1-3] However, it is still controversial and there is no any detailed discussion about its polymerization mechanism under high pressure. Here, we report the in-situ high pressure Raman spectra and powder neutron diffraction results on CD3CN, which indicates a minor phase transition at 5 GPa. The neutron diffraction shows that CD3CN keeps the orthorhombic phase from 1.66 GPa to 20.58 GPa which is very close to the reaction pressure. The week hydrogen bonding CD...N arranges the molecule into 3-dimensional framework which can be treated as two sets of diamond like structures interpenetrating with each other. Interestingly, the observed N...D distance is 1.984 Å at 20.58 GPa, shorter than the van der Waals distance of N...H (2.75 Å) by 28%. The van der Waals separation is often taken as a reference distance for the molecular instability. Thus, a hydrogen transfer process during the polymerization can be concluded. This deduction is also supported by the solid state NMR and FTIR results of the recovered polymerized CH3CN (p-CH3CN) from high pressure. In addition, the atomic pair distribution function and Raman spectra indicate the p-CD3CN or p-CH3CN has a random packed layer structure with nano-graphene lattice.

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 and electronic properties of fluorene: A joint experimental and theoretical high-pressure study

2006 ◽  
Vol 73 (2) ◽  
Author(s):  
Georg Heimel ◽  
Kerstin Hummer ◽  
Claudia Ambrosch-Draxl ◽  
Withoon Chunwachirasiri ◽  
Michael J. Winokur ◽  
...  
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Electronic Properties ◽  
High Pressure Study

scholarly journals Crystal and Electronic Structure Engineering of Tin Monoxide by External Pressure

2020 ◽  
Author(s):  
Kun Li ◽  
Junjie Wang ◽  
Vladislav A. Blatov ◽  
Yutong Gong ◽  
Naoto Umezawa ◽  
...  
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Band Gap ◽  
Low Pressure ◽  
External Pressure ◽  
Widespread Application ◽  
Space Group ◽  
Tin Monoxide ◽  
High Possibility ◽  
Pressure Phase

Abstract Although tin monoxide (SnO) is an interesting compound due to its p-type conductivity, a widespread application of SnO has been limited by its narrow band gap of 0.7 eV. In this work, we theoretically investigate the structural and electronic properties of several SnO phases under high pressure through employing van der Waals (vdW) functionals. Our calculations reveal that a metastable SnO (A-SnO), which possesses space group P21/c and a wide band gap of 1.9 eV, is more stable than l-SnO at pressures higher than 80 GPa. Moreover, a stable (space group P2/c) and a metastable (space group Pnma) phases of SnO appear at pressures higher than 120 GPa. Energy and topological analyses show that P2/c-SnO has a high possibility to directly transform to t-SnO at around 120 GPa. Our work also reveals that h-SnO is a necessary intermediate state between high-pressure phase Pnma-SnO and low-pressure phase o-SnO for the phase transition path Pnma-SnO ®u-SnO ® g-SnO. Two phase transition analyses indicate that there is a high possibility to synthesize h-SnO under high-pressure conditions and have it remain stable under normal pressure. Finally, our study reveals that the conductive property of -SnO can be engineered in a low-pressure range (0-9 GPa) through a semiconductor-to-metal transition, while maintaining transparency in the visible light range.

High-pressure study of the structural phase transition in Cu1.875Te

2021 ◽  
Vol 186 ◽  
pp. 110020
Author(s):  
Liang Ma ◽  
Jinqun Cai ◽  
Yingying Wang ◽  
Mi Zhou ◽  
Guangtao Liu ◽  
...  
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Structural Phase Transition ◽  
Structural Phase ◽  
High Pressure Study

scholarly journals Band-gap tuning of lead halide perovskites using a sequential deposition process

2014 ◽  
Vol 2 (24) ◽  
pp. 9221-9225 ◽  
Author(s):  
Sneha A. Kulkarni ◽  
Tom Baikie ◽  
Pablo P. Boix ◽  
Natalia Yantara ◽  
Nripan Mathews ◽  
...  
Keyword(s):  
Band Gap ◽  
Deposition Process ◽  
Sequential Deposition ◽  
Halide Perovskites ◽  
Band Gap Tuning ◽  
Lead Halide

Demonstration of band-gap tuning of mixed anion lead halide perovskites (MAPb(I1−xBrx)2 (0 ≤ x ≤ 1)) by means of a sequential deposition process.

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