Search results

1

Dynamics of Domains in (CH_{3}NH_{3})_{5}Bi_{2}Br_{11} Crystals

100%

Matyjasek K., Jakubas R.

Acta Physica Polonica A

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1994

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vol. 85

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issue 5

835-841

EN

The nucleation and movement of the 180° domain walls in CH_{3}NH_{3})_{5}Bi_{2}Br_{11} crystals has been investigated by means of liquid crystals. The various shapes of domains during the polarization reversal has been observed and discussed, considering that the type of nucleation is the controlling factor in the propagation of the walls.

2

Dilatometric Study of the Phase Transition in (CH_{3}NH_{3})_{5}Bi_{2}Cl_{11}

100%

Pykacz H., Jakubas R.

Acta Physica Polonica A

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1991

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vol. 79

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issue 5

695-697

EN

The paper reports a dilatometric study on (CH_{3}NH_{3})_{5}Bi_{2}Cl_{11} single crystals. It is shown that elongation of the crystal is continuous but linear thermal expansion coefficients are discontinuous at phase transition temperature.

3

Influence of Defects on Dielectric Properties of (CH_{3}NH_{3})_{5}Bi_{2}X_{11} (x=Cl, Br) Crystals

81%

Μróz J., Pykacz H., Jakubas R.

Acta Physica Polonica A

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1995

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vol. 88

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issue 2

369-374

EN

Influence of defects on ferroelectric properties of the (CH_{3}ΝΗ_{3})_{5}Bi_{2}Χ_{11} (Χ = Cl, Br) crystals in the vicinity of ferro-paraelectric phase transition was investigated. γ-irradiation of both crystals insignificantly shifts Tc towards higher temperature. The substitution of chlorine atoms by iodine ones in the (CH_{3}ΝΗ_{3})_{5}Bi_{2}Cl_{11} crystal drastically reduces the magnitude of the dielectric permittivity but does not influence on the temperature behaviour of the spontaneous polarization.

4

^1H NMR Study of Molecular Dynamics of 4-apyH Cation under High Hydrostatic Pressure

81%

Medycki W., Świergiel J., Jakubas R., Hołderna-Natkaniec K.

Acta Physica Polonica A

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2005

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vol. 108

|

issue 1

161-164

EN

Polycrystalline [4-NH_2C_5H_4NH] SbCl_4 and [4-NH_2C_5H_4NH] SbCl_6 have been investigated by proton NMR methods between 120 K and 370 K under hydrostatic pressure of 0.1 and 520 MPa. Reduction in the dipolar second moment is interpreted in terms of cation reorientation. Activation energies characterizing the motion increase with increasing pressure.

5

Phase Transitions in (CH_{3}NH_{3})_{5}Bi_{2}X_{11} (X=Cl, Br) Crystals

81%

Pykacz H., Mróz J., Jakubas R.

Acta Physica Polonica A

|

1993

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vol. 84

|

issue 6

1085-1091

EN

Electric properties of (CH_{3}NH_{3})_{5}Bi_{2}Cl_{11} and (CH_{3}NH_{3})_{5}Bi_{2}Br_{11} single crystals in the direction of the crystallographic b-axis were studied. The samples tested were natural crystal seeds in the form of thin plates, whose crystallographic b-axis coincides with the normal to the plate. Measurements of the pyroelectric coefficient were performed near the high temperature phase transition and spontaneous polarization from the paraelectric phase down to helium temperature. The attempt of explanation of the anomalous electric properties of these crystals has been presented.

6

Thermal Expansion of (CH_{3}NH_{3})_{5}Bi_{2}X_{11} (X=Cl, Br) Crystals in the Temperature Range from 80 to 300 K

81%

Jakubas R., Franqois P., Lefebvre J.

Acta Physica Polonica A

|

1994

|

vol. 85

|

issue 3

579-583

EN

Thermal expansion studies on (CH_{3}NH_{3})_{5}Bi_{2}Cl_{11} and (CH_{3}NH_{3})_{5}Bi_{2}Br_{11} in the temperature range 80-350 K are reported. The dilatometric measurements revealed a considerable similarity with respect to the anisotropy of dilatations of both isomorphous crystals. A diffused thermal anomaly was found around 170 K in (CH_{3}NH_{3})_{5}Bi_{2}Cl_{11} crystal.

7

Dielectric and Pyroelectric Studies on [N(CH_{3})_{4}]_{3}Bi_{2}X_{9} (X = Cl, Br)

81%

Jakubas R., Bator G., Mróz J.

Acta Physica Polonica A

|

1995

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vol. 87

|

issue 3

663-669

EN

Dielectric properties of [N(CH_{3})_{4}]_{3}Bi_{2}X_{9} (X = Cl, Br) single crystals were measured in the frequency range 1 kHz - 1 MHz in the vicinity of structural phase transitions of first-order type at 152 K (Cl) and 183 K (Br). The pyroelectric effect was observed in [N(CH_{3})_{4}]_{3}Bi_{2}[N(CH_{3})_{4}]_{3}Bi_{2}Cl_{9} at structural phase transition (T_{c} = 152 K) with the ΔP_{s} of the order of 10^{-5} C m^{-2}. Polarized microscope observations show appearance of ferroelectric domain structure in [N(CH_{3})_{4}]_{3}Bi_{2}Br_{9} within the low temperature phase.

8

The Dielectric Studies of Ferroelectric [NH_2(CH_3)_2]_3Sb_2Cl_9 Crystals under Moderate Pressure

81%

Zdanowska-Frączek M., Olszewski M., Frączek Z., Jakubas R.

Acta Physica Polonica A

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2007

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vol. 112

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issue 3

549-556

EN

The effect of pressure on the dielectric properties of [NH_2(CH_3)_2]_3Sb_2Cl_9 crystal was analyzed for a few values of hydrostatic pressure within the range from 0.1 MPa to 300 MPa and for temperatures from the range of 220-350 K. The measuring frequency was 1 kHz. The pressure-temperature phase diagram obtained was nonlinear. The temperature dielectric permittivity anomalies related to the paraelectric-ferroelectric phase transition temperature (T_c) gradually increase up to 66 MPa and then decrease with subsequent increase in pressure. The character of the temperature dielectric permittivity anomalies, typical of the continuous ferroelectric transition, remains unchanged with increasing pressure. Additionally, the pressure dependences of the Curie-Weiss constants for the crystal in paraelectric (C_+) and ferroelectric (C_-) phases were evaluated and discussed. The results indicated a complex mechanism of the ferroelectric phase transition.

9

The Internal Bias Field of Ferroelectric (CH_{3}NH_{3})_{5}Bi_{2}Br_{11}

81%

Pykacz H., Mróz J., Jakubas R.

Acta Physica Polonica A

|

1992

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vol. 81

|

issue 6

667-673

EN

Spontaneous polarization of (CH_{3}NH_{3})_{5}Bi_{2}Br_{11} crystals has been measured and the ferroelectric hysteresis loop has been studied. The observed time changes in the polarization have been ascribed to the change in the internal bias field of the crystal. Measurement results have also been discussed for the lower phase transition (T_{II} = 77 K).

10

Pyroelectric and Dilatometric Studies on the Low Temperature Ferroelectric Phase Transition of (CH_3NH_3)_5Bi_2Br_{11}

81%

Dziedzic J., Mróz J., Jakubas R.

Acta Physica Polonica A

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2005

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vol. 108

|

issue 3

505-511

EN

The results of the linear thermal expansion studies on (CH_3NH_3)_5Bi_2Br_{11} single crystals in the temperature range 60-340 K are presented. The thermal anomaly in the vicinity of 77 K is assigned to the phase transition classified as close to first order type. The pyroelectric measurements of (CH_3NH_3)_5Bi_2Br_{11} were carried out in the range of 45-320 K along the a- and c-axis. The step-like change in the spontaneous polarization along the a-axis at 77 K indicates a discontinuous character of ferroelectric transition.

11

Phase Transitions in (CH_{3})_{2} CHNH_{3}CdCl_{3} Crystal

71%

Krzewska U., Jakubas R., Dacko S., Czapla Z., Waśkowska A.

Acta Physica Polonica A

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1992

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vol. 81

|

issue 3

379-384

EN

The crystal of (CH_{3})_{2}CHNH_{3}CdCl_{3} was grown and its physical properties were investigated. On the ground of DSC, dylatometric and dielectric investigations the phase transition at 390 K on heating process was revealed. On cooling two phase transitions at 382 K and 352 K were found. Polarized microscope observations show appearance of ferroelastic domain structure and cracks at 390 K on heating. On cooling the observed domain structure vanishes at 352 K.

12

IINS, FT-IR and DFT Study of the Internal Dynamics of [4-apyH][SbCl_4]

62%

Hołderna-Natkaniec K., Natkaniec I., Mikuli E., Swiergiel J., Khavryutchenko V., Jakubas R.

Acta Physica Polonica A

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2008

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vol. 113

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issue 4

1117-1130

EN

A combination of infrared and inelastic incoherent neutron scattering spectroscopies with the density functional theory and semi-empirical calculations was applied to propose an assignment of the vibrational spectra of 4-aminopyridine chloroantimonate(IV).

Refine search results

Dynamics of Domains in (CH_{3}NH_{3})_{5}Bi_{2}Br_{11} Crystals

Dilatometric Study of the Phase Transition in (CH_{3}NH_{3})_{5}Bi_{2}Cl_{11}

Influence of Defects on Dielectric Properties of (CH_{3}NH_{3})_{5}Bi_{2}X_{11} (x=Cl, Br) Crystals

^1H NMR Study of Molecular Dynamics of 4-apyH Cation under High Hydrostatic Pressure

Phase Transitions in (CH_{3}NH_{3})_{5}Bi_{2}X_{11} (X=Cl, Br) Crystals

Thermal Expansion of (CH_{3}NH_{3})_{5}Bi_{2}X_{11} (X=Cl, Br) Crystals in the Temperature Range from 80 to 300 K

Dielectric and Pyroelectric Studies on [N(CH_{3})_{4}]_{3}Bi_{2}X_{9} (X = Cl, Br)

The Dielectric Studies of Ferroelectric [NH_2(CH_3)_2]_3Sb_2Cl_9 Crystals under Moderate Pressure

The Internal Bias Field of Ferroelectric (CH_{3}NH_{3})_{5}Bi_{2}Br_{11}

Pyroelectric and Dilatometric Studies on the Low Temperature Ferroelectric Phase Transition of (CH_3NH_3)_5Bi_2Br_{11}

Phase Transitions in (CH_{3})_{2} CHNH_{3}CdCl_{3} Crystal

IINS, FT-IR and DFT Study of the Internal Dynamics of [4-apyH][SbCl_4]