In this paper the feasibility of Fe(Se,Te) Coated Conductors (CC) on simple Rolling-Assisted Biaxilly Textured Substrate (RABiTS) template is studied. Starting from commercially available NiW5% tapes from Evico which have an out-of-plane orientation of about 6° and an in-plane orientation of 5.3°, a RABiTS template for Fe(Se,Te) coated conductors was realized depositing CeO2 thin films on the metallic tape. The oxide buffer layers, deposited via Pulsed Laser Ablation, have an out-of-plane and an in-plane orientation suitable for Fe(Se,Te) deposition and act as a chemical barrier against Ni diffusion. The Fe(Se,Te) deposited on such a simple template show a superconducting transition Tc of 18 K, very high upper critical field values with a Tc,0 of only 3 K in 18 T and self-field transport isotropic critical current values of 10 5 A/cm 2 at 4.2 K, which is reduced of less than one order of magnitude up to 16 T.
The introduction of artificial pinning sites in YBa2 Cu3O7−d (YBCO) epitaxial thin films has been\ud
obtained by pulsed laser deposition ͑PLD͒ technique from YBCO-BaZrO3 ͑BZO͒ composite targets\ud
with BZO concentration ranging from 2.5 to 7 mol %. The typical critical temperature, Tc , drop\ud
observed in YBCO-secondary phase films grown by PLD has been successfully recovered by\ud
increasing the deposition temperature. Transport properties analyses revealed improved pinning\ud
force values for YBCO-BZO films for BZO concentration above 5 mol %. These films exhibited an\ud
anomalous dual peak structure which has been ascribed to the presence of two pinning\ud
contributions. The crossover field, Bm , separating these two pinning regimes has been observed to\ud
be temperature independent suggesting the occurrence of the matching field effect. The measured\ud
value of Bm agreed with the matching field value, B⌽ = Knd⌽0 , as evaluated from transmission\ud
electron microscopy investigations. The mark of this phenomenon is retained down to 10 K, making\ud
YBCO-BZO more performing than pristine YBCO films at applied magnetic fields below Bm in all\ud
the temperature range inspected. On the contrary, in the high magnetic field range ͑above Bm͒, the\ud
effectiveness of correlated pinning is progressively reduced on lowering the temperature suggesting\ud
that at low temperatures the dominant pinning contribution arises from isotropic pinning centers
Pulsed laser deposited thin Y Ba2Cu3O7−x (YBCO) films with pinning additions of 5 at. % Ba2Y TaO6 (BYTO) were compared to films with 2.5 at. % Ba2Y TaO6 + 2.5 at. % Ba2Y NbO6 (BYNTO) additions. Excellent magnetic flux-pinning at 77 K was obtained with remarkably high irreversibility fields greater than 10 T (YBCO-BYTO) and 11 T (YBCO-BYNTO), representing the highest ever achieved values in YBCO films.
The complex refractive index of a LiF crystal surface layer irradiated by low-energy electrons is modified by the stable formation of color centers embedded in it. A simplified dipole-electromagnetic field interaction model has been adopted in order to estimate the dispersion curves of colored LiF from a single optical transmittance measurement. The excellent agreement with the corresponding experimental curves (obtained by means of spectrophotometry and ellipsometry) demonstrates this to be a promising approach for LiF-based optical waveguide characterization.
The structural and chemical evolution of propionate based low fluorine
YBa2Cu3O7 − δ
(YBCO) precursor during the conversion thermal treatment to obtain
superconducting film has been investigated by both x-ray photoelectron
and diffraction techniques in a set of partially converted films on
SrTiO3
single crystals. The pyrolysis temperature within the range 400–480 °C
mainly affects the copper valence state with an increase of the
Cu2 +
fraction with temperature with respect to the
Cu1 +
oxidation state. During the subsequent thermal treatment up to
700 °C, the reduction of fluorine content is mainly ascribed to the hydrolysis of
YF3. At higher temperatures,
Ba hydrolysis, Y2Cu2O5
and YBCO phase formation (nucleation at
700 °C and
725 °C,
respectively) have been observed. The temperature dependences of the formation and decomposition of
YBCO, Y2Cu2O5
and Ba-oxyfluoride were evaluated by x-ray diffraction measurements. The reaction path
emerging from these analyses agrees with the one observed for YBCO films obtained
with the standard MOD method based on metal tri-fluoroacetate precursors.
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