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1
Content available remote

Raman Scattering and Electrical Properties of TGS:PCo (9%) Crystal as Ambient Temperature IR Detector

100%
Malekfar R., Daraei A.
Acta Physica Polonica A
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2008
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vol. 114
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issue 4
859-867
EN
We developed and adequately characterized the triglycine sulfate family crystals doped with specific molar percent of cobalt phosphate, TGS:PCo (9%). The crystals were grown by slow evaporation technique and the growth rates of different crystallographic planes are rather faster in comparison with the plane growth rates of pure TGS crystals. The introduction of Co^{2+} ion as an active optical element to the structure of TGS crystal leads to optimization of some parameters such as optical quality, stability at ambient condition, Curie temperature, stronger Raman peaks, etc. Three new peaks at 460, 620 and 1368 cm^{-1} were observed in the dispersive back scattering Raman spectra of the grown TGS:PCo (9%) crystal in comparison with the pure triglycine sulfate crystal.
2
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Raman Spectra and Structural Data of the Nanocrystalline KTP (KTiOPO_4) Synthesized by Pechini Method

100%
Malekfar R., Cheraghi A., Ahmadi G., Khanzadeh M.
Acta Physica Polonica A
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2009
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vol. 116
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issue 6
1073-1075
EN
Nanocrystalline KTP powders are synthesized using a modified Pechini method. The structural and lattice modes of the products are investigated via X-ray diffraction, micro Raman backscattering spectroscopy, UV/vis/NIR and FT-IR transmission spectroscopy. The Debye-Scherrer formula is used to confirm the grain sizes estimated by the scanning electron microscopy slides.
3
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Dynamics of Hydrogen Bonds in TGS Crystals Observed by Means of Measurements of Pyroelectric Currents Induced by Linear Changes of Temperature

80%
Trybus M., Paszkiewicz T., Woś B.
Acta Physica Polonica A
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2017
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vol. 132
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issue 1
161-163
EN
The study of pyroelectric response of monocrystalline TGS cubic specimens to changes of temperature induced by linear and pulse heating of three mutually perpendicular pairs of cube sides demonstrated a complicated structure of signals. We attribute their forms to the activation of various hydrogen bonds between glycine G1, G2, and G3 molecules. In the case of pulse heating the pyroelectric signal is observed also in the paraelectric phase.
4
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The Dielectric Studies of Ferroelectric [NH_2(CH_3)_2]_3Sb_2Cl_9 Crystals under Moderate Pressure

80%
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.
5
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Baric Shift of Phase Transition in Ammonium Sulfate Crystals

80%
Gaba V.
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|
issue 1
126-128
EN
The influence of uniaxial mechanical pressures (σ_m ≤ 200 bar) on the spectral (300-800 nm) and temperature (77-300 K) dependences of the refractive indices n_{i}, the birefringence Δn_{i} and the phase transition point in ammonium sulfate crystals are studied. It is established that the uniaxial pressure does not change character of the dispersion dn_{i}/dλ, but only its value λ The shift of the phase transition in ammonium sulfate under the uniaxial mechanical pressure is analyzed.
6
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Temperature-and-Spectral Deformations of the Optical Indicatrix of Rubidium Sulphate Single Crystal

80%
Gaba V.
|
|
issue 1
129-132
EN
The paper deals with newly investigated temperature-and-spectrum dependences of principal birefringences (Δ n_{i}(λ,T)-i=X, Y, Z; λ=250÷850 nm; T = 4.2-1100 K), and temperature dependence of the optic-axial angle (2V(T) - T=4.2-1100 K) for two laser lines 632.8 nm and 441.1 nm of Rb_{2}SO_{4} crystals. Based on the temperature dependence of the optic-axial angle, the second point of birefringence sign inversion has been found. Newly obtained is the temperature-and-spectrum diagram of the uniaxial state of the optical indicatrix at the "isotropic points" and in the hexagonal phase of Rb_{2}SO_{4}. Based on the temperature behavior of the birefringence and optic-axial angle it was supposed that hexagonal-orthorhombic phase transition in rubidium sulfate can be a second-order phase transition. Found is the inversion of birefringence dispersion in the X and Y directions at 400 K and 620 K, respectively.
7
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Birefringence of Mechanically Stressed Potassium Tetrachlorine Zincanate Crystals

80%
Stadnyk V., Gaba V., Kohut Z.
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issue 1
133-135
EN
The spectral and baric dependences of the birefringence Δn_{i} of K_{2}ZnCl_{4} crystals were studied. It is shown that the dispersion Δn_{i}(λ) is normal and sharply increases on approaching the absorption edge. It is established that the uniaxial pressures do not change the character but only the values of the dispersions dΔn_{i}/dλ and temperature dependences of dΔn_{i}/dT.
8
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Influence of Uniaxial Pressure on the Refractive Properties of Rubidium Tetrachlorine Zincanate Crystals

80%
Stadnyk V., Gaba V., Kohut Z., Popel O.
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|
issue 1
136-138
EN
The effect of uniaxial pressure (σ_m ≤ 200 bar) on the spectral (300-800 nm) and temperature (77-300 K) dependences of the refractive indices of Rb_{2}ZnCl_{4} crystals are investigated. The baric dependences of the electron polarizability, specific refraction and the parameters involved in the Sellmeier formula are calculated.
9
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Content available

Dielectric Properties of K_{1-x}(NH_4)_xH_2PO_4 (x= 0.095) Crystal

61%
Kaszyński J., Trybuła Z., Małuszyńska H.
Acta Physica Polonica A
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2005
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vol. 108
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issue 1
103-106
EN
Temperature dependences of the dielectric permittivity were studied for the ferroelectric K_{1-x}(NH_4)_xH_2PO_4 mixed crystal. The experiments revealed presence of the beginning of the dipolar glass - embryos in the concentration of ammonium x=0.095. Observations of the dielectric relaxations show much bigger effect domain mechanism than the one related to the growth of clusters of the dipolar glass.
10
Content available remote

Electrical properties and memory effect in the field effect transistor based on organic ferroelectric insulator and pentacene

61%
Matsuo Y., Ijichi T., Yamada H., Hatori J., Ikehata S.
Open Physics
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2004
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vol. 2
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issue 2
357-366
EN
We have fabricated a field effect transistor (FET) based on an organic ferroelectric insulator and molecular conductor, and investigated the electrical properties and memory effects on the PEN-FET. We have observed a drastic change in the drain current at around the coercive electric fieldE c of the organic ferroelectric insulator in not only a FET (PEN-FET) based on a pentacene (PEN) film but also a FET (IPEN-FET) based on an iodine doped PEN film. The magnitude of the change of the drain current for the IPEN-FET is 200 times larger than that for the PEN-FET. It is expected from these results that the PEN-FET (especially the IPEN-FET) is an improvement in such devices, since it operates at a low gate electric field accompanied by the appearance of the spontaneous polarization in the organic ferroelectric insulator. In addition, we have found that the drain current for the PEN-FET does not return to the initial drain current ofE G=0 V/cm for more than one week, even if the gate electric field is changed to 0 V/cm from 500 V/cm(>E c). From these results, it is suggested that the PEN-FET becomes a memory device.
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