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The Influence of Partial Isomorphic Substitution on Electronic and Optical Parameters of ABSO₄ Group Crystals

100%

Shchepanskyi P., Gaba V., Stadnyk V., Rudysh M., Brezvin R., Piasecki M.

Acta Physica Polonica A

2018

vol. 133

issue 4

819-823

First principles calculations of band energy, density of states and dielectric function of K_{1.75}(NH₄)_{0.25}SO₄ single crystals in Pnma structure is performed in the framework of density functional theory. In order to describe the exchange-correlation interaction the general gradient approximation and local density approximation are used. Character and genesis of main energy bands of the crystal are discussed and comparison with data set for K₂SO₄ isomorphic crystal performed. The influence of partial isomorphic substitution K→ NH₄ found itself mainly in altering the bottom of conduction band and decrease of band gap value. From the dielectric functions dependences, the refractive indices dispersion and absorption coefficient spectra are deduced. Obtained refractive indices satisfactorily agree with experimental data in the visible spectrum region.

Specific Features of Content Dependences for Energy Gap in In_{x}Tl_{1-x}I Solid State Crystalline Alloys

84%

Kashuba A., Piasecki M., Bovgyra O., Stadnyk V., Demchenko P., Fedorchuk A., Franiv A., Andriyevsky B.

Acta Physica Polonica A

2018

vol. 133

issue 1

68-75

A series of In_{x}Tl_{1-x}I (x=0.4-0.9) single crystalline solid state alloys were successfully synthesized by the vertical Bridgman method. For the first time the density functional theory based band structure calculations are performed and features of the band energy dispersion are discussed. Comparison with the experimental energy gap E_{g} obtained from the optical photoconductivity is discussed. An essential role of the localized defects and excitons in formation of the edge photoconductivity is analyzed. Relation between the crystal structure and photoconductivity of the materials studied is discussed. Also the origin of the principal valence and conduction bands is explored. Experimental measurements of the band gap E_{g} by the optical and photoconductivity methods have given opposite dependences with respect to the indium content x. Features of the photoconductivity spectra for different crystallographic directions have been discussed with taking into account the chemical bonds anisotropy.

Significant Increment of the Dielectric Permittivity and Domain Properties in the (1-x)PbTiO3-x(Na0.5Bi0.5)TiO3 Crystals

83%

Czaja P., Piasecki M., Zapart M. B., Suchanicz J., Konieczny K., Michniowski J., Sitko D., Stachowski G., Kluczewska-Chmielarz K., Czaja P., Piasecki M., Zapart M. B., Suchanicz J., Konieczny K., Michniowski J., Sitko D., Stachowski G., Kluczewska-Chmielarz K.

vol. 65

issue 1

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2 Acta Physica Polonica A

1 Archives of Metallurgy and Materials

1 2020

2 2018

3 Piasecki M.

2 Stadnyk V.

1 Andriyevsky B.

1 Bovgyra O.

1 Brezvin R.

1 Czaja P.

1 Demchenko P.

1 Fedorchuk A.

1 Franiv A.

1 Gaba V.

1 Kashuba A.

1 Kluczewska-Chmielarz K.

1 Konieczny K.

1 Michniowski J.

1 Rudysh M.

1 Shchepanskyi P.

1 Sitko D.

1 Stachowski G.

1 Suchanicz J.

1 Zapart M. B.

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The Influence of Partial Isomorphic Substitution on Electronic and Optical Parameters of ABSO₄ Group Crystals

Specific Features of Content Dependences for Energy Gap in In_{x}Tl_{1-x}I Solid State Crystalline Alloys

Significant Increment of the Dielectric Permittivity and Domain Properties in the (1-x)PbTiO3-x(Na0.5Bi0.5)TiO3 Crystals