The morphology and structure of damaged regions (tracks) produced by swift heavy 167, 77, and 46 MeV ¹³²Xe²³⁺ ions in YBCO-based second generation industrial high temperature superconductors wires (2G HTS) were studied using transmission electron microscopy. It was shown that ions produce tracks aligned along the ion trajectory but of morphology depending on their energy: continuous, nearly continuous, or discontinuous tracks like prolate ellipsoids of 10–15 nm in length and spheroids of 5 nm in diameter. The damaged regions of about 5 nm in diameter contain an amorphous material with a lower density compared to the pristine YBCO. The material density drops from 6300 kg m⁻³ for YBCO matrix to 3600 kg m⁻³ inside the tracks. Barium enrichment was found in the vicinity of the track at a distance of about 10 nm from the center of the defect. Ion damage tracks with different morphologies showed different effectivenesses as pinning centers. Tracks composed of discontinuous pinning centers—spheroids of about 5 nm in diameter—bring the best enhancement of the critical current density. It occurs for the lowest ion energy (46 MeV) in the range of energy loss of 8.9 keV/nm–4.7 keV/nm for Xe ions. The samples showed highest critical current densities of 56 MA/cm² (4.2 K) and 3 MA/cm² (77 K) in self-field, while in magnetic fields of 8 T, the values of 17 MA/cm² (4.2 K) and 1.6 MA/cm² (77 K) were achieved. The reduction of the superconducting volume corresponding to the amorphous radiation defects did not exceed 4% from the total sample volume.

High–resolution transmission electron microscopy shows that metal nanoparticles sinter within a fraction of a second under an electron beam at ‘room temperature’ as long as classical models of thermal equilibrium apply. Images exhibit crystal planes that change in orientation with time as if the particle was undergoing melting and resolidification processes. We explore whether these dynamical effects are the result of heating or transformation effects in the electron microscope or quantum fluctuations in small systems.

This work reports experimental results of the quantitative determination of oxygen and band gap measurement in the TiN_x electrodes in planar TiN_x top/La:HfO₂/TiN_x bottom MIM stacks obtained by plasma enhanced atomic layer deposition on SiO₂. Methodological aspects of extracting structural and chemical information from (scanning) transmission electron microscopy imaging (bright field and high angular annular dark field), energy dispersive X-ray spectrometry and electron energy loss spectroscopy are thoroughly considered. The study shows that the oxygen concentration is higher in the TiN_xO_y bottom electrode (about 14.2 ± 0.1 at. %) compared to the TiN_xO_y top electrode (about 11.4 ± 0.5 at. %). The following average stoichiometric formulas are TiN₀.₅₂O₀.₂₀ top and TiN₀.₅₄O₀.₂₆ bottom for top and bottom electrodes, respectively. The amount of oxygen incorporated into TiN_x during PEALD because of oxygen impurities in the plasma is minor compared to that because of diffusion from SiO₂ and HfO₂. This asymmetry, together with results on a sample grown on a Si substrate, shows that incorporating oxygen impurity from the plasma itself is a minor part compared to diffusion from the SiO₂ substrate and HfO₂ dielectric during the PEALD growth. We observe the presence of TiO₂ at the interface between the Hf oxide layer and the Ti nitride electrodes as well as at the SiO₂ interface. EELS analysis led to a band gap ranging from 2.2 to 2.5 eV for the bottom TiN_xO_y and 1.7–2.2 eV for the top TiN_xO_y, which is in fair agreement with results obtained on the top TiN_x electrode (1.6 ± 01 eV) using optical absorption spectra. Measurement of sheet resistance, resistivity and temperature coefficient of resistance by a four-point probe on the top TiN_xO_y electrode from 20 to 100 °C corresponds to the typical values for semiconductors.