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Wyświetlanie 1-7 z 7
Tytuł:
Clean bulk YBaCuO superconductors doped by paramagnetic ions of Sm and Yb
Autorzy:
Jirsa, M.
Volochová, D.
Kováč, J.
Diko, P.
Powiązania:
https://bibliotekanauki.pl/articles/1054700.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.25.Ha
74.25.Op
74.25.Sv
74.60.Ge
74.72.-h
Opis:
The recently developed clean cuprate technology was employed to study the effect of tiny amounts of paramagnetic Yb and Sm ions on electromagnetic properties of bulk YBaCuO. Small samples of about 1.5×1.5×0.5 mm³ were measured by vibrating sample magnetometer in the field range ±9 T and temperatures 30 K to 10 K in the non-superconducting tetragonal state and 300 K to 70 K in the orthorhombic, superconducting state. In the latter case, we observed the reversible paramagnetic moment above T_{C}, similar as in the tetragonal state. Below T_{C} an irreversible magnetic moment was observed from which critical current density, J_c, was evaluated using the extended Bean model. The effect of doping by Yb and Sm ions on J_c was studied and a correlation between J_c and the total paramagnetic moment was found. Both J_c(B) and the normalized pinning force density as a function of the reduced magnetic field were analyzed in terms of the classical model and discussed with respect to the material anisotropy, giving us at least a rough idea on the type of the effective pinning type and mechanism.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 1027-1029
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electromagnetic Properties of Melt-Grown YBaCuO Superconductors Doped by Gd and Sm
Autorzy:
Jirsa, M.
Rameš, M.
Volochová, D.
Radušovská, M.
Diko, P.
Powiązania:
https://bibliotekanauki.pl/articles/1371409.pdf
Data publikacji:
2014-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.25.Ha
74.25.Op
74.25.Sv
74.60.Ge
74.72.-h
Opis:
Electromagnetic properties of $YBa_{2}Cu_{3}O_{y}$ samples melt-grown in air and doped with small amounts of light rare earth (LRE) ions Gd and Sm were studied. The LRE doping creates a point-like disorder contributing to the second peak on the magnetization curve. In the field range of the second peak the average magnetic moment, $M_{av}$, deduced from the magnetization curves exhibited strong fluctuations. $M_{av}$ is commonly regarded as an equilibrium moment close to the thermodynamic reversible one, obeying in intermediate fields a logarithmic field dependence. However, in our experiments $M_{av}(B)$ curves failed to follow such a dependence below irreversibility line. $M_{av}(B)$ curves deduced from rather static measurements, done by SQUID magnetometer still showed the disturbance but significantly weaker. It indicates that this feature reflects the vortex dynamics in the second peak region. Its scaling with temperature was found to coincide with that of the pinning force.
Źródło:
Acta Physica Polonica A; 2014, 126, 1; 326-327
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The effect of Sm addition on the microstructure and superconducting properties of YBCO bulk superconductors
Autorzy:
Volochová, D.
Diko, P.
Piovarči, S.
Antal, V.
Kováč, J.
Jirsa, M.
Powiązania:
https://bibliotekanauki.pl/articles/1054772.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.72.-h
74.62.Dh
81.10.Fq
61.72.-y
74.25.Ha
74.25.Sv
Opis:
The effect of Sm addition on the microstructure and superconducting properties of Y-Ba-Cu-O (YBCO) bulk superconductors has been studied. Nominal composition: 1 mol YBa₂Cu₃O_{7-δ} + 0.25 mol Y₂O₃ + 1 wt% CeO₂ was enriched with different amounts of SmBa₂Cu₃O_y powder with the aim to increase critical current density, J_c, especially in higher magnetic fields by introducing additional pinning centers. Single grain YBCO bulk superconductors with SmBa₂Cu₃O_y (Y123-Sm) addition were prepared by the optimized top seeded melt growth process. Microstructure analysis, performed by polarized light microscope, revealed that SmBa₂Cu₃O_y addition leads to a higher amount of slightly coarser Y₂BaCuO₅ particles, which is related to lower critical current densities (J_c ≈ 6×10⁴ A/cm²) of the YBCO samples with SmBa₂Cu₃O_y addition in low magnetic fields. On the other hand, an enhancement of critical current density, J_c, in higher magnetic fields was observed for Y123-Sm samples. Moreover, a maximum trapped magnetic field, B_{tmax}, of 564 mT at 77 K in Y123-Sm, x=0.0025 sample (Ø 17.2 mm) was 43% higher than that for YBCO sample without any addition.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 1009-1011
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Microstructure and Properties of Y-123/Y-211 Bulk Superconductors with $BaCeO_{3}$ and $BaO_{2}$ Addition
Autorzy:
Zmorayova, K.
Antal, V.
Radusovska, M.
Piovarci, S.
Volochova, D.
Diko, P.
Powiązania:
https://bibliotekanauki.pl/articles/1371616.pdf
Data publikacji:
2014-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.25.Bt
74.25.Ha
74.62.Bf
74.62.Dh
81.10.Fq
81.30.Fb
Opis:
$YBa_{2}Cu_{3}O_{7-δ}$ (YBCO) bulk single-grain superconductors were prepared by a TSMG process. $CeO_{2}$, $BaCeO_{3}$ and $BaO_{2}$ powders were added to nominal composition $Y_{1.5}Ba_{2}Cu_{3}O_{7}$ with the aim to refine $Y_{2}BaCuO_{5}$ (Y-211) secondary particles. Added powders were refined by milling in a friction milling and characterized by X-ray powder difractometry. Thermal properties of the systems were characterized by DTA. Microstructure of samples was studied by PLM. Successful refinement of Y-211 particles size was confirmed by IP measurements. Transition temperatures and field dependences of the magnetic moment for further determination of the critical current densities were obtained using a VSM.
Źródło:
Acta Physica Polonica A; 2014, 126, 1; 366-367
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Growth Rate of $YBa_2Cu_3O_7$ Bulk Crystals in $Y_{1.5}Ba_2Cu_3$ System with $CeO_2$ Addition
Autorzy:
Zmorayová, K.
Šefčiková, M.
Volochová, D.
Kalmanová, M.
Piovarči, S.
Diko, P.
Powiązania:
https://bibliotekanauki.pl/articles/1418272.pdf
Data publikacji:
2012-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.25.Bt
74.62.Bf
74.62.Dh
81.10.Fq
81.20.Ev
81.30.Fb
Opis:
The growth rate of $Y_1Ba_2Cu_3O_{x}$ bulk single grain (in fact single crystal) superconductors in the system with composition $Y_{1.5}Ba_2Cu_3O_{x}$ and $CeO_2$ addition was studied in the temperature range 991-1001°C. It is shown that the growth rate of bulk crystal is different for a- and c-growth direction. Slower measured growth rate in studied system than in pure $Y_1Ba_2Cu_3O_{x}$ is related to the composition shift to the three-phase field containing CuO.
Źródło:
Acta Physica Polonica A; 2012, 122, 4; 725-727
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Time Dependent Changes in Ag Doped YBCO Superconductors
Autorzy:
Volochová, D.
Antal, V.
Diko, P.
Šefčiková, M.
Zmorayová, K.
Kováč, J.
Weber, H.
Chaud, X.
Powiązania:
https://bibliotekanauki.pl/articles/1535451.pdf
Data publikacji:
2010-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.25.Ha
74.25.Sv
74.62.Bf
74.62.Dh
74.62.Fj
Opis:
Magnetization measurements at 77 K were conducted on the single-crystalline samples of YBCO superconductor doped with Ag prepared by the top-seeded melt-growth process. The single-grain samples had a nominal composition $Y_{1.5}Ba_2(Cu,Ag)_3O_{y}$. Magnetization measurements on the samples, oxygenated by two different processes: by standard oxygenation and by high pressure oxygenation, repeated after 24 months, revealed time dependent changes in magnetization behaviour and critical transition temperatures, T_{c}, which could be associated with redistribution of oxygen vacancies and their interaction with Ag dopant atoms.
Źródło:
Acta Physica Polonica A; 2010, 118, 5; 1047-1048
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of Sm and Yb Pollution on Superconducting Properties of YBCO Bulk Superconductors
Autorzy:
Volochová, D.
Jurek, K.
Radušovská, M.
Piovarči, S.
Antal, V.
Kováč, J.
Jirsa, M.
Diko, P.
Powiązania:
https://bibliotekanauki.pl/articles/1371573.pdf
Data publikacji:
2014-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.60.Bf
74.72.-h
81.40.Rs
74.25.Ha
74.81.Bd
74.25.Op
Opis:
$YBa_{2}Cu_{3}O_{7-δ }$ (YBCO, Y-123) bulk superconductors with a nominal composition $Y_{1.5}Ba_{2}Cu_{3}O_{x}$ and 1 wt% $CeO_{2}$ addition were prepared by the Top Seeded Melt Growth (TSMG) process. Small single-crystalline pieces, cut from the $SmBa_{2}Cu_{3}O_{y}$ (Sm-123) bulk, were used for seeding of epitaxial growth. Wavelength-dispersive spectrometry (WDS) confirmed the presence of 0.1 wt% Sm from the seed and 0.25 wt% Yb from the substrate, practically in the whole sample volume. The influence of this Sm and Yb contamination on superconducting properties of grown bulk materials is reported.
Źródło:
Acta Physica Polonica A; 2014, 126, 1; 358-359
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-7 z 7

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