Search results

1

Dielectric Relaxation Phenomena in SBN Single Crystals Doped with Ce

100%

Korchak Y., Kapustianyk V., Fedor B., Girnyk I., Eliyashevskyi Y.

Acta Physica Polonica A

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2011

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vol. 119

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issue 6

871-874

EN

The dielectric study of Sr_{0.73}Ba_{0.27}Nb_2O_6:Ce (SBN) crystals along [010] crystallographic axis was performed in the temperature region of 310-360 K and frequency range from 25 Hz up to 1 MHz. The thermal dipole relaxation of quasi-Debye-type for this orientation of sample was observed in both investigated structural phases. The phase transition was most clearly seen from the temperature dependence of the relaxation time at T_{c} = 320 K. The relaxation processes were related to the collective oscillations of the Nb-O bonds in the two different type corner-sharing NbO_6 octahedra aligned along c-axis.

2

Dielectric and Birefringent Properties of [(CH_3)_2NH_2]_5Cd_2CuCl_{11} Solid Solutions in the Region of Their Phase Transitions

86%

Eliyashevskyy Y., Kapustianyk V., Dacko S., Czapla Z., Batiuk A., Sveleba S.

Acta Physica Polonica A

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2006

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vol. 109

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issue 2

171-178

EN

On the basis of the optical and dielectric investigations of [(CH_3)_2NH_2]_5Cd_2CuCl_{11} solid solutions the existence of phase transitions at T_1=175 K and T_2=117.5 K was confirmed. Both phase transitions were found to be shifted toward lower temperatures with respect to the corresponding transitions in the "host" [(CH_3)_2NH_2]_5Cd_3Cl_{11} crystals. It was found that the proton conductivity in [(CH_3)_2NH_2 ]_5Cd_2CuCl_{11} crystals is realized through the Grotthus mechanism. The investigations of the birefringent properties confirmed existence of the structural changes at T_0=320 K connected with the complex co-operative effect involving weakening of the hydrogen bonds and modification of the Jahn-Teller distortion with temperature.

3

Structural Properties and Temperature Behaviour οf Optical Absorption Edge in Polycrystalline ZnO:X (Cu,Ag) Films

86%

Kulyk B., Figà V., Kapustianyk V., Panasyuk M., Serkiz R., Demchenko P.

Acta Physica Polonica A

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2013

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vol. 123

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issue 1

92-97

EN

Silver- and copper-doped ZnO films were prepared by radio-frequency magnetron sputtering on glass substrates. The influence of dopants content on the structural, morphological properties as well as on evolution of the optical absorption edge was considered. It has been found that Ag- and Cu-doped ZnO films are characterized by wurtzite crystalline structure with the preferred direction of crystalline orientation (002). The sizes of grains within the films were found to be dependent on the type of dopant. The temperature evolution of the optical absorption edge is described by the modified Urbach rule that reflects polycrystalline nature of the material. The corresponding parameters concerning electron- (exciton-) phonon interaction, phonon energies and temperature changes of the band-gap were determined and analysed.

4

Phase Transitions and Fundamental Ferroelectric Dispersion in DMAAl_{1-x}Cr_{x}S Crystals

73%

Kapustianyk V., Eliyashevskyy Y., Czapla Z., Dacko S., Czupiński O., Rudyk V., Serkiz R., Sereda S., Semak S.

Acta Physica Polonica A

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2015

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vol. 127

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issue 3

791-794

EN

This paper presents the results of investigations of the temperature dependence of heat capacity and dielectric dispersion in the vicinity of ferroelectric-ferroelastic phase transition of dimethylammonium metal sulphate hexahydrate crystals DMAAl_{1-x}Cr_{x}S. In particular, it is shown that the isomorphous substitution of metal ion noticeably changes the temperature of phase transition and parameters of the fundamental ferroelectric dispersion observed around T_{c1}. These changes are explained in terms of clusters sizes and dynamics in the framework of order-disorder type phase transition mechanism.

5

High Temperature Stability of Electrical and Optical Properties of Bulk GaN:Mg Grown by HNPS Method in Different Crystallographic Directions

59%

Sadovyi B., Amilusik M., Staszczak G., Bockowski M., Grzegory I., Porowski S., Konczewicz L., Tsybulskyi V., Panasyuk M., Rudyk V., Karbovnyk I., Kapustianyk V., Litwin-Staszewska E., Piotrzkowski R.

Acta Physica Polonica A

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2016

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vol. 129

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issue 1a

A-126-A-128

EN

Single crystals of Mg-doped GaN grown by high nitrogen pressure solution method in different crystallographic directions ([0001], [101̅1], and [101̅1̅]) were investigated in order to determine thermal stability of their electrical and optical properties. Obtained dependences of resistivity, the Hall coefficient and energy shift of Mg-related photoluminescence peak on annealing temperature allow to suggest that incorporation of Mg in GaN is significantly influenced by the direction of the crystallization front.

Refine search results

Dielectric Relaxation Phenomena in SBN Single Crystals Doped with Ce

Dielectric and Birefringent Properties of [(CH_3)_2NH_2]_5Cd_2CuCl_{11} Solid Solutions in the Region of Their Phase Transitions

Structural Properties and Temperature Behaviour οf Optical Absorption Edge in Polycrystalline ZnO:X (Cu,Ag) Films

Phase Transitions and Fundamental Ferroelectric Dispersion in DMAAl_{1-x}Cr_{x}S Crystals

High Temperature Stability of Electrical and Optical Properties of Bulk GaN:Mg Grown by HNPS Method in Different Crystallographic Directions