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.

In this paper we study the feasibility of Fe(Se, Te) coated conductors on a simple rolling-assisted biaxially textured substrate (RABiTS) template. Starting from commercially available Ni–5 at% W tapes which show an out-of-plane orientation of about 7° and an in-plane orientation around 5°, we realized a RABiTS template for Fe(Se, Te) coated conductor fabrication by depositing CeO ₂ thin films on the metallic tape. The oxide buffer layers, deposited via pulsed laser ablation, exhibit an out-of-plane and an in-plane orientation suitable for Fe(Se, Te) deposition and act as a chemical barrier against Ni diffusion. Fe(Se, Te) thin films deposited on such a simple template show a superconducting transition at 16 K and very high upper critical field values with a Δ T _c,0 of only 3 K in 18 T. The transport critical current reaches values of 1.7 × 10 ⁵ A cm ⁻² at 4.2 K in self-field and is reduced by less than one order of magnitude up to 18 T, remaining isotropic with respect to the magnetic field direction.

The introduction of artificial pinning sites in ${\text{YBa}}_2{\text{Cu}}_3{\text{O}}_{7-\delta }$ (YBCO) epitaxial thin films has been obtained by pulsed laser deposition (PLD) technique from YBCO-${\text{BaZrO}}_3$ (BZO) composite targets with BZO concentration ranging from 2.5 to $7\text{mol}\mathrm{\%}$ . The typical critical temperature, $T_c$ , drop observed in YBCO-secondary phase films grown by PLD has been successfully recovered by increasing the deposition temperature. Transport properties analyses revealed improved pinning force values for YBCO-BZO films for BZO concentration above $5\text{mol}\mathrm{\%}$ . These films exhibited an anomalous dual peak structure which has been ascribed to the presence of two pinning contributions. The crossover field, $B_m$ , separating these two pinning regimes has been observed to be temperature independent suggesting the occurrence of the matching field effect. The measured value of $B_m$ agreed with the matching field value, $B_{\Phi }=K{n}_d{\Phi }_0$ , as evaluated from transmission electron microscopy investigations. The mark of this phenomenon is retained down to 10 K, making YBCO-BZO more performing than pristine YBCO films at applied magnetic fields below $B_m$ in all the temperature range inspected. On the contrary, in the high magnetic field range (above $B_m$ ), the effectiveness of correlated pinning is progressively reduced on lowering the temperature suggesting that at low temperatures the dominant pinning contribution arises from isotropic pinning centers.

Pulsed laser deposited thin Y Ba₂Cu₃O_7−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.

Electrical and mechanical characterizations of YBCO coated conductors diffusion joints obtained in a 2 mm wide, Cu stabilizer free commercial tape provided by Superpower Inc. were reported. Two conductor pieces were overlapped for a length of 20 mm and kept in contact under a pressure as high as 80 MPa. A face-to-face approach was used, with or without an additional Ag tape insert. The joint was realized by Ag diffusion at a temperature of 200 and 400°C in N₂ and O₂ atmosphere, respectively. The resistivity of the joint was measured at 77 K in N₂ bath. The mechanical properties of the joint were characterized by means of single-lap tensile test operated at room temperature at a rate of 0.5 mm/min. The best results were obtained by high temperature joining in O₂ atmosphere. The resistivity of the joints was as low as 3.1 × 10^-12 ¿ m². This value is almost halved if an Ag insert is used. The mechanical properties of the joints are strongly dependent on the use of an Ag insert, since maximum load as high as 60 N can be applied if no additional insert is used. This value enhances to about 100 N when an Ag insert is employed. However, the joint obtained at low temperature in N₂ atmosphere is also interesting since the joint resistivity was slightly increased to 4.7 × 10^-12 ¿ m² and a maximum load as high as 50 N was obtained indicating that diffusion joints can be safely handled. These results are promising in perspective of oxygen free diffusion joints in Cu stabilized coated conductors.