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The epitaxial growth of Zr-doped CeO 2 (CZO) films by chemical solution deposition (CSD) on single crystal substrates such as Al 2 O 3 , SrTiO 3 and Y 2 O 3 -stabilized ZrO 2 (YSZ) and their use as buffer layers for Fe(Se,Te) film growth are reported. The growth of 30 nm thin CZO films is mostly dominated by dewetting issues, leading to highly incomplete substrate coverage due to the strong tendency of CZO grains to agglomerate. This effect is less severe on YSZ substrate and, in addition, can be fully controlled by setting the deposition temperature at 950 • C and operating under Ar-H 2 reducing atmosphere. These conditions promote the growth of epitaxial and compact CZO films on YSZ, showing a flat surface morphology with root-mean-square roughness around 2.5 nm. Preliminary results on Fe(Se,Te) film deposited by pulsed laser deposition on CZO-buffered YSZ are reported. Although good epitaxial growth is achieved on CZO buffer layer, Fe(Se,Te) films exhibit poor superconducting properties. On the other hand, Fe(Se,Te) films show excellent properties when a seed layer is used, exhibiting a sharp superconducting transition at about 17 K and a critical current density exceeding 1 MA cm −2 at 4.2 K in self field. The main role of the seed layer, consisting of a non-superconducting Fe(Se,Te) film, is to favour the crystal and chemical matching between buffer layer and film, allowing for the growth of high-quality superconducting Fe(Se,Te) at deposition temperature as low as 200 • C.In perspective of applications, this result is a significant step towards process simplification and cost reduction of Fe(Se,Te)-based coated conductor technology development, being the first demonstration of superconducting Fe(Se,Te) films grown on CSD buffer layer.

We present a comparative study of vortex pinning in chemically deposited YBaO nanocomposite films, with the aim of correlating the preparation method to the superconducting properties. Two sets of samples have been prepared by different low fluorine routes (one set followed the in situ approach), with different starting YBCO coating solution and with a different amount of BaZrO. The short-range vortex pinning properties have been assessed using a contactless microwave (48 GHz) technique, which yielded the vortex pinning constant (Labusch parameter) and the vortex viscosity as a function of the applied field up to 0.8 T, and for temperatures between 60 K and. The results were compared to more usual (long-range vortex motion) measurements. Despite the supposed similarity in pinning as determined from, we found significant differences between the pinning properties of the two sets of samples. It appears that the in situ approach results in stronger pinning at microwaves in the whole temperature range explored, and that this behavior is due to the smaller dimensions of BaZrO nanoparticles. This information can be very useful in the search of optimized chemical route to strong pinning superconducting nanocomposite materials

High-performing superconducting YBa2Cu3O7–x (YBCO) films are fabricated by a chemical solution deposition methodology through novel barium-deficient low-fluorine solutions. The precursor solutions, distinguished for being straightforward, inexpensive and eco-friendly, allow us to reduce the growing temperature of YBCO down to 750 °C. We investigated the influence of the growing temperatures on both the microstructure and superconducting properties of YBCO films by using conventional thermal annealing and flash-heating approaches. A clear correlation between the growing temperature (Tg) and the superconducting performance of the films was obtained with improved performances observed at low Tg.