Effect of illumination on negative linear expansion of TlGaSe2 layered crystals

Seyidov, МirHasan Yu.; Suleymanov, Rauf A.; Yakar, Emin; Abdullayev, N. A.; Mammadov, T. G.

doi:10.1016/j.jpcs.2008.05.012

Cited by 15 publications

(13 citation statements)

References 18 publications

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“…Generally, chalcogen vacancies in layered chalcogenides may produce changes in structural, physical, and chemical properties of materials. [ 70–72 ] The presence of such vacancies in crystal structure of materials can promote to formation of chemical bond strains in the atomic network due to a charge redistribution localized near a number of vacancy sites, which may be associated with a macroscopic mechanical strain in the sample. These strains should necessarily be taken into consideration, since they could significantly reduce the electronic bandgap and produce extra majority carriers (due to movement of the Fermi energy to the edge of conductive/valence band) in materials compared to the pristine compound.…”

Section: Resultsmentioning

confidence: 99%

A Study of Thermoelectric Performance of TlGaSe₂ Layered Dichalcogenides from First‐Principles Calculations: Vacancy Defects Modeling and Engineering

Çaydaşı

Mintaş

Chumakov

et al. 2021

Physica Status Solidi (b)

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Herein, the thermoelectric performance of TlGaSe2 ternary layered dichalcogenides is evaluated by applying ab initio density functional theory calculations combined with Boltzmann's transport equation. A novel approach to design the intrinsic structural defects via Se‐anion vacancies in unit cell has been developed. Two kinds of Se‐vacancy defects in host TlGaSe2 crystal lattice are engineered: the single vacancy defect induced intrinsically in the unit cell (1×1×1) and in the supercell lattice (1×1×4). It is found that the electrical transport properties and thermoelectric efficiency of this semiconductor could be significantly altered by introducing Se‐vacancy states into crystalline structure. In addition, simulation shows that inclusion of Se‐vacancy defects significantly improves the thermoelectric efficiency as well as the thermoelectric power factor and figure of merit (ZT) values of this compound. Additionally, the thermoelectric performance of TlGaSe2 is estimated by means of the electronic fitness function calculations in the valence and conduction edges. The results demonstrate that TlGaSe2 with introduced Se‐vacancies may be a perspective material for thermoelectric applications.

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Section: Resultsmentioning

confidence: 99%

A Study of Thermoelectric Performance of TlGaSe₂ Layered Dichalcogenides from First‐Principles Calculations: Vacancy Defects Modeling and Engineering

Çaydaşı

Mintaş

Chumakov

et al. 2021

Physica Status Solidi (b)

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“…It is seen that illumination and electric field give opposite effects on LEC: while the electric field leads to increasing LEC, illumination substantially decreases the LEC; both effects are observed only at T Ͻ 130 K. Below, we will try to explain the observed experimental findings based on the electronic nature of the negative thermal expansion of TlGaSe 2 crystals we proposed earlier. 10 …”

Section: Resultsmentioning

confidence: 99%

“…[10][11][12] It was shown that the monoclinic structure of these crystals is very close to tetragonal, and elastic and thermal properties can be treated even in the framework of a hexagonal structure. 3 The well known relations for the LECs in crystals with an axial symmetry 18 can be used in this case,…”

Section: Discussionmentioning

confidence: 99%

Effect of electric field on negative linear expansion of ferroelectric-semiconductor TlGaSe2

Seyidov

Suleymanov

Yakar

et al. 2009

Journal of Applied Physics

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The effect of electric field on the thermal expansion of the TlGaSe2 ferroelectric-semiconductor with a layer crystalline structure has been investigated. A strong transformation of negative linear expansion coefficient in the layer plane has been observed as a result of the applied electric field. It was concluded that internal electric fields created by local polarized states in the ferroelectric- semiconductor are responsible for a negative thermal expansion and its behavior under the electric field. Predominantly, the electrostriction effect is the driving mechanism of the lattice deformation of TlGaSe2 crystals at low temperatures.

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“…energy bandgaps of the annealed B1 sample. In previous work, a strong influence of the memory effect on the linear thermal -expansion coefficients of the pristine TlGaSe 2 has been reported [27,29,30,[65][66][67][68]. The comparison of the thermalexpansion results [27,29,[65][66][67][68] was deemed necessary to consider the contribution of volume dilation effect to the optical band gaps of annealed B1 sample.…”

Section: Varshnimentioning

confidence: 99%

Modification of the optical and elastic properties of TlGaSe₂ layered semiconductor produced by the memory effect

Cengiz,

Gören,

Sönmez

et al. 2023

Phys. Scr.

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A comparative analysis of the temperature behaviors of optical and elastic properties of TlGa Se 2 single crystals under a memory effect experimental condition are presented for the first time. A memory effect condition suggests that the sample is thermally annealed inside the incommensurate (INC) phase for a time interval the corresponding physical parameters is measured experimentally. From ultrasound velocity measurements, carried out before and after the thermal annealing process subjected to the sample, the noticeable changes in the temperature variation of the longitudinal ultrasonic wave velocity associated with the elastic constants C 33 of TlGa Se 2 due to the memory effect was detected. Our results reveal that thermal annealing performed at the INC - phase has some influence on the optical absorption of TlGa Se 2 crystals in the visible spectral region. We assumed that thermal annealing within INC - phase is accompanied with the appearance, inside TlGa Se 2 samples, a new quasiperiodic frozen structure formed from the intrinsic defects migrated into the lowest energy diffusion barriers of the INC - modulation wave. Such structural modulation is incommensurate with the underlying lattice of TlGa Se 2 and can lead to changes in the electronic band structure and the optical bandgaps of TlGa Se 2 .

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Effect of illumination on negative linear expansion of TlGaSe2 layered crystals

Cited by 15 publications

References 18 publications

A Study of Thermoelectric Performance of TlGaSe₂ Layered Dichalcogenides from First‐Principles Calculations: Vacancy Defects Modeling and Engineering

A Study of Thermoelectric Performance of TlGaSe₂ Layered Dichalcogenides from First‐Principles Calculations: Vacancy Defects Modeling and Engineering

Effect of electric field on negative linear expansion of ferroelectric-semiconductor TlGaSe2

Modification of the optical and elastic properties of TlGaSe₂ layered semiconductor produced by the memory effect

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Effect of illumination on negative linear expansion of TlGaSe2 layered crystals

Cited by 15 publications

References 18 publications

A Study of Thermoelectric Performance of TlGaSe2 Layered Dichalcogenides from First‐Principles Calculations: Vacancy Defects Modeling and Engineering

A Study of Thermoelectric Performance of TlGaSe2 Layered Dichalcogenides from First‐Principles Calculations: Vacancy Defects Modeling and Engineering

Effect of electric field on negative linear expansion of ferroelectric-semiconductor TlGaSe2

Modification of the optical and elastic properties of TlGaSe2 layered semiconductor produced by the memory effect

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A Study of Thermoelectric Performance of TlGaSe₂ Layered Dichalcogenides from First‐Principles Calculations: Vacancy Defects Modeling and Engineering

A Study of Thermoelectric Performance of TlGaSe₂ Layered Dichalcogenides from First‐Principles Calculations: Vacancy Defects Modeling and Engineering

Modification of the optical and elastic properties of TlGaSe₂ layered semiconductor produced by the memory effect