Polytypes in ferroelectric TlInS<sub>2</sub> and its dielectric and optic properties

Alekperov, O. Z.; Ibragimov, G. B.; Nadjafov, A. I.; Fakix, A. R.

doi:10.1002/pssc.200881193

Cited by 18 publications

(20 citation statements)

References 2 publications

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“…As reported by McMorrow et al , such defects in TlGaSe 2 form nearly regular defect subsystem with one defect per every four layers in paraphase (C‐phase). According to Alekperov et al , TlInS 2 , encountered in its most common variety as β‐polytype (monoclinic) may also have large amount of planar defects.…”

Section: Resultsmentioning

confidence: 99%

Band gap exciton in ferroelectric TlInS₂: Dimensionality and screening

Mamedov

Shim

Okada

et al. 2015

Physica Status Solidi (b)

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This work reports two-dimensionality of band-gap exciton in layered ferroelectric TlInS 2 , accessed by spectroscopic phase modulated ellipsometry in a wide range of temperatures embracing normal, incommensurate, and commensurate phases of this material. A significant decrease in exciton binding energy is observed upon approaching the temperature region of the incommensurate phase on cooling or heating. The effective static rather than optic dielectric screening is shown to be responsible for the observed behavior of exciton binding energy that remains larger than the energy of the longitudinaloptical phonon at all accessed temperatures. The temperature dependence of this screening is remarkable in that it obeys Currie-Weiss law. The values of the exciton's reduced mass and three-dimensional effective Bohr radius are obtained. The former keeps constant to be 0.928 the mass of the free electron while the latter irregularly changes with temperature, remaining within 14-19 Ålimits. The last values correspond to the doubled thickness of a single layer.

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Section: Resultsmentioning

confidence: 99%

Band gap exciton in ferroelectric TlInS₂: Dimensionality and screening

Mamedov

Shim

Okada

et al. 2015

Physica Status Solidi (b)

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“…The main peculiarity of the PTs in β-TlInS 2 crystals consists in the fact that different polytypes can coexist in the crystalline matrix [12,13]. They are characterized by different lattice parameters c. The unit cell parameter c for different polytypes is equal to c = 2c*, 4c*, 8c* and 16c*, with c* = 15.18 Å.…”

Section: VImentioning

confidence: 99%

Temperature dependences of optical indicatrix and thermal expansion parameters of TlIn(S1�xSex)2 solid solutions (x = 0, 0.02 and 0.06)

Say¹,

Martynyuk-Lototska²,

Mys³

et al. 2020

Ukr. J. Phys. Opt.

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Temperature dependences of relative elongation, thermal expansion coefficient, birefringence increment and angle of optical indicatrix rotation are studied for TlIn(S 1-x Se x) 2 crystals (x = 0, 0.02 and 0.06). We have found that all of these crystals reveal at least two diffused phase transitions (PTs), from normal phase to incommensurate phase and from incommensurate phase to ferroelectric phase. The temperature regions where these PTs take place are determined. A lowtemperature PT represents a diffused PT of the first order. We have detected with our techniques that the solid solution with x = 0.02 is non-uniformly stressed. These internal stresses can be caused by a polytype structure. An additional anomaly in the temperature dependence of thermal expansion coefficient occurring at the temperature T 1 = 214 K in the compound with x = 0.06 also points to the existence of polytype structure.

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“…Excess of In atoms ((TlS) 0.5 -(InS) 0.5 + 0.1-0.01a.t. % In) in the melt causes growing of Tr-TlInS 2 , which has nearly the same physical and crystal parameters as M-TlInS 2 , differing from it only by angle between lattice parameters a and b , which is slightly greater than for M-crystal (π/2) [7]. However, the excess of Tl ((TlS) 0.5 -(InS) 0.5 + 0.1-0.01a.t.…”

Section: Introductionmentioning

confidence: 87%

Growth of orthorhombic and tetragonal modifications of TlInS₂ from its monoclinic phase

Alekperov¹,

Ibragimov

Axundov

et al. 2009

Phys. Status Solidi (c)

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Orthorhombic (O) and tetragonal (T) modifications of TlInS2 were grown by sulfur vapor annealing of monoclinic (M) crystals. Lattice parameters and syngony of the grown crystals were determined from X‐ray investigations (Laue, Weissenberg, rocking crystal and powder diffractions). The lattice parameters a = 6.88 Å, b = 14.04 Å, c = 4.02 Å, Z = 4 and a = b = 7.76 Å, c = 26.6 Å, Z = 20 as well as space groups (SG), P212121 and P41212 were ascribed to O and T modifications, correspondingly. The transition of M‐crystals to O‐ or T‐phase takes place through the intermediate disordered state of M‐phase in which the unit packets with c ≈ 15 Å are randomly positioned along the c‐axis. From photoconductivity (PC) edge it was found that the band gap of O‐TlInS2 (Eg = 2.52 ± 0.01 eV) is slightly higher whereas that of T‐TlInS2 (Eg = 1.87 ± 0.01 eV) is noticeably lower than the band gap of M‐TlInS2. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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Polytypes in ferroelectric TlInS₂ and its dielectric and optic properties

Cited by 18 publications

References 2 publications

Band gap exciton in ferroelectric TlInS₂: Dimensionality and screening

Band gap exciton in ferroelectric TlInS₂: Dimensionality and screening

Temperature dependences of optical indicatrix and thermal expansion parameters of TlIn(S1�xSex)2 solid solutions (x = 0, 0.02 and 0.06)

Growth of orthorhombic and tetragonal modifications of TlInS₂ from its monoclinic phase

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Polytypes in ferroelectric TlInS2 and its dielectric and optic properties

Cited by 18 publications

References 2 publications

Band gap exciton in ferroelectric TlInS2: Dimensionality and screening

Band gap exciton in ferroelectric TlInS2: Dimensionality and screening

Temperature dependences of optical indicatrix and thermal expansion parameters of TlIn(S1�xSex)2 solid solutions (x = 0, 0.02 and 0.06)

Growth of orthorhombic and tetragonal modifications of TlInS2 from its monoclinic phase

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Polytypes in ferroelectric TlInS₂ and its dielectric and optic properties

Band gap exciton in ferroelectric TlInS₂: Dimensionality and screening

Band gap exciton in ferroelectric TlInS₂: Dimensionality and screening

Growth of orthorhombic and tetragonal modifications of TlInS₂ from its monoclinic phase