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1

Dielectric Study of Pressure Induced fcc-sc Phase Transition in Fullerene C_{60}

100%

Trybuła Z., Krupski M.

Acta Physica Polonica A

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2000

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vol. 98

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issue 4

389-392

EN

Phase transition in polycrystalline fullerene C_{60} from fcc phase to a simple cubic phase sc induced by hydrostatic pressure up to 0.5GPa was studied by dielectric method. Pressure coefficient dT_{c}/dp=144±8 K/GPa was determined. This value is consistent with pressure coefficients obtained with other experimental techniques.

2

EPR Study of Fe^{3+} Paramagnetic Centers in Doped Triglycine Sulphate Crystals

100%

Łoś S., Trybuła Z.

Acta Physica Polonica A

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2002

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vol. 101

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issue 2

279-287

EN

This paper presents EPR study of Fe^{3+} in triglycine sulphate doped with Fe^{3+} crystal. Fe^{3 +} ion is in a high spin state S=5/2. EPR signal can be detected only below 200 K. At 4.2 K the EPR spectrum results from three non-equivalent sites of Fe^{3+} ions. The spin Hamiltonian: H=β BĝS+D[S^2_z-(1/3)S(S+1)]+E(S^2_x-S^2_y) has been applied to describe the spectrum. The zero field splitting parameter in this case fulfills the condition: D≫hν. An experimental spectrum reflects clearly only two resonance transitions: |±1/2ã (the lowest Kramers doublet) and |±3/2〉 (the middle Kramers doublet). The iron complexes occupy interstitial positions in the crystal with distorted octahedral or tetrahedral co-ordination.

3

Free Radicals in K and Rb Admixtured Fullerene C_{60}

81%

Stankowski J., Kempiński W., Byszewski P., Trybuła Z.

Acta Physica Polonica A

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1993

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vol. 84

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issue 6

1117-1123

EN

Molecules of C_{60} form Van der Waals type crystals. The observations reported here concern EPR investigations of such C_{60} samples with only a slight amount of Rb or K. Detected defects are (C_{60})^{+} or (C_{60})^{y-} ion-radicals. A hole (h) or trapped electron (t) are localized on one fullerene ball. In the case of potassium fullerites C_{60}:K the line shape of EPR signal was of the Dysonian form which is characteristic of conducting electrons in metal. The EPR lines of holes (C_{60})^{+} are characterized by g_{h} ≥ g_{0} whereas for electrons g_{t} is below the value g_{0} = 2.0023 characteristic of a free electron (g_{t} ≤ g_{0}). The EPR linewidth 2ΔB^{h}_{1s} of the (C_{60})^{+} weakly increased with decreasing temperature whereas the EPR linewidth attributed to the electron 2ΔB^{t}_{1s} significantly decreases with decreasing temperature. The C_{60}:K sample reached superconducting phase below T_{c} = 11 K which is significantly less than T_{c} = 16.5 K observed for K_{x}C_{60} where 2 ≤ x ≤ 4.

4

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

81%

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.

5

Pseudorotational Averaging of EPR Spectrum of Cu(II)O_{5} Complex in YBa_{2}Cu_{3}O_{7-δ} in Low Temperatures

81%

Stankowski J., Kempiński W., Trybuła Z.

Acta Physica Polonica A

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1991

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vol. 80

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issue 4

571-581

EN

In low temperatures the condensation of oxygen was found to occur at 05 site in an elementary cell of YBa_{2}Cu_{3}O_{7-δ} being the fifth ligand forming the CuO_{5} complex around Cul copper in chain. This change of coordinantion from CuO_{4} to CuO_{5} is the origin of a pseudorotation related to a strong vibronic coupling of two distorted configurations: a tetragonal pyramid C_{4v} and a trigonal bipyramid D_{3h}, which yields a pseudocubic EPR spectrum in low temperatures. The averaged spectroscopic splitting coefficient is related to a superposition of vibronically coupled orbital states |x^{2} - y^{2}〉 and |3z^{2} - r^{2}〉. The averaged spectrum was for the first time observed in low temperatures since the oxygen condensation in YBa_{2}Cu_{3}O_{7-δ} at 05 site of the chain occur only when oxygen undergoing fast diffusion among the chains, gets localized with decreasing temperature. The activation energy of oxygen desorption from the 05 site is 36 K.

6

The Local Order in KTaO_3 Admixtured by the Ions of Li^+

71%

Kaszyńska K., Trybuła Z., Glinchuk M., Bykov I., Laguta V.

Acta Physica Polonica A

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2005

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vol. 108

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issue 2

379-383

EN

The low temperature behavior of the KTaO_3 type incipient ferroelectric crystals is of constant interest. The quantum fluctuations reduce the transition to the ferroelectric state in these crystals. It is possible that the small amount of the dopant Li^+ can lead, through the elastic interactions, to local glass-like short-range order or even to the relaxor ferroelectric order for x>2.6%. We presented that the low lithium doped x=0.005 KTaO_3 crystals exhibit the dielectric dispersion ofε andε", suggesting the glass-like behavior in the low temperature range.

7

Electric Conductivity of Carbon Nanoparticles Stimulated by Electric Field

61%

Markowski D., Kempiński W., Kempiński M., Trybuła Z., Kaszyńska K., Śliwińska-Bartkowiak M.

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issue 3

457-458

EN

Host-guest interactions can be the unique method of spin manipulation in nanoscale. Strong changes in spin localization are generated when potential barriers between nanographitic units of activated carbon fibers are modified by interaction with adsorbed molecules. Stronger modifications occur when dipolar guest molecules are stimulated with external electric field. We report experimental results which show the influence of electric field on the spin localization in activated carbon fibers.

8

Superconducting Regions and Kondo Effect of MgB_2 Formed by Implantation of Magnesium Ions into Boron Substrate

52%

Trybuła Z., Kempiński W., Andrzejewski B., Piekara-Sady L., Kaszyński J., Trybuła M., Piekoszewski J., Stanisławski J., Barlak M., Richter E.

Acta Physica Polonica A

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2006

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vol. 109

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issue 4-5

657-660

EN

The results of investigation of the polycrystalline boron implanted by magnesium and argon plasma pulse treatment are presented. The four-probe electric conductivity measurements and magnetically modulated microwave absorption showed the presence of superconducting islands below the temperature of 25 K. Below T=23 K we detected the Kondo effect, a logarithmic increase in the resistivity as the temperature is lowered, due to iron impurity.

9

Birefringent and Dielectric Properties of [N(C_{2}H_{5})_{4}]_{2}ZnBr_{4} and [N(C_{2}H_{5})_{4}]_{2}CdBr_{4} Crystals

52%

Sveleba S., Mokryi V., Polovinko I., Kapustyanik V., Trybuła Z., Petrenko P., Kiosse G., Kravtsov V.

Acta Physica Polonica A

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1993

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vol. 83

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issue 6

777-784

EN

Dielectric and birefringent properties of [N(C_{2}H_{5})_{4}]_{2}ZnBr_{4} and [N(C_{2}H_{5})_{4}]_{2}CdBr_{4} crystals were investigated. It has been ascertained that two phase transitions manifest themselves in the temperature dependencies є(T) for [N(C_{2}H_{5})_{4}]_{2}CdBr_{4} crystal - a second-order transition at T_{1} = 311 K and a first-order one - at T_{2} = 39 K (∆T_{2} = 11 K). Besides two earlier known phase transitions in [N(C_{2}H_{5})_{4}]_{2}ZnBr_{4} at T_{1} = 350 K and T^{cool}_{2} = 282.8 K (∆T_{2} ≈ 2.3 K), the additional one was found at T*_{2} = 287.0 K, both on the cooling and heating runs. On the basis of the data about the peculiarities of dielectric and optical properties in the vicinity of T_{2} one can made the conclusion about the ferroelectric character of the phase, situated between T*_{2} and T^{cool}_{2}.

10

Superconductivity of MgB_2 Layers Prepared on Silicon Substrate by Implantation of Magnesium Ions into Boron Substrate

52%

Trybuła Z., Kempiński W., Łoś S., Kaszyńska K., Trybuła M., Piekoszewski J., Werner Z., Barlak M.

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issue 2

323-325

EN

The results of investigation of the MgB_2 layers prepared on silicon substrate by implantation of Mg ions into boron substrate are presented. After implantation the annealing processes were carried out at temperatures 673 K, 773 K, and 873 K in a furnace in an atmosphere of flowing Ar-4%H_2 gas mixture. The samples were characterized by: four-probe electric conductivity measurements and magnetically modulated microwave absorption. Our results showed that due to silicon substrate the diffusion of implanted Mg ions into boron materials should be limited, and the superconducting phase forms a continuous MgB_2 layer and the resistivity for all samples fall down to zero below T_{c}. The transition temperature T_{c} becomes higher with increasing annealing temperature: T_{c}=18 K (for annealing at T_{A}=673 K), T_{c}=20 K (for annealing at T_{A}=773 K), and T_{c}=27 K (for annealing at T_{A}=873 K).

11

Formation of Superconducting Regions of MgB_2 by Implantation of Boron Ions into Magnesium Substrate

42%

Trybuła Z., Kempiński W., Andrzejewski B., Piekara-Sady L., Kaszyński J., Piekoszewski J., Werner Z., Richter E., Prokert F., Stanisławski J., Barlak M.

Acta Physica Polonica A

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2005

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vol. 108

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issue 1

165-170

EN

The results of investigation of the MgB_2 inter-metallic compound with the use of boron ions implantation and plasma pulse treatment are presented. The samples were characterized by: four-probe electric conductivity measurements, magnetically modulated microwave absorption, and magnetic measurements. For hydrogen and argon pulsed plasma treatment the samples with T_c ranging from 10 K to 32 K were obtained. The superconducting phase does not form a continuous layer since the resistivity does not fall down to zero. Apparently, separate islands of superconducting phase are connected through metallic Mg paths. All samples are still below the percolation threshold.

Refine search results

Dielectric Study of Pressure Induced fcc-sc Phase Transition in Fullerene C_{60}

EPR Study of Fe^{3+} Paramagnetic Centers in Doped Triglycine Sulphate Crystals

Free Radicals in K and Rb Admixtured Fullerene C_{60}

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

Pseudorotational Averaging of EPR Spectrum of Cu(II)O_{5} Complex in YBa_{2}Cu_{3}O_{7-δ} in Low Temperatures

The Local Order in KTaO_3 Admixtured by the Ions of Li^+

Electric Conductivity of Carbon Nanoparticles Stimulated by Electric Field

Superconducting Regions and Kondo Effect of MgB_2 Formed by Implantation of Magnesium Ions into Boron Substrate

Birefringent and Dielectric Properties of [N(C_{2}H_{5})_{4}]_{2}ZnBr_{4} and [N(C_{2}H_{5})_{4}]_{2}CdBr_{4} Crystals

Superconductivity of MgB_2 Layers Prepared on Silicon Substrate by Implantation of Magnesium Ions into Boron Substrate

Formation of Superconducting Regions of MgB_2 by Implantation of Boron Ions into Magnesium Substrate