Nanoscale Stoichiometric Analysis of a High-Temperature Superconductor by Atom Probe Tomography

Abstract

The functional properties of the high-temperature superconductor Y1Ba2Cu3O7-δ (Y-123) are closely correlated to the exact stoichiometry and oxygen content. Exceeding the critical value of 1 oxygen vacancy for every five unit cells (δ>0.2, which translates to a 1.5 at% deviation from the nominal oxygen stoichiometry of Y7.7Ba15.3Cu23O54-δ ) is sufficient to alter the superconducting properties. Stoichiometry at the nanometer scale, particularly of oxygen and other lighter elements, is extremely difficult to quantify in complex functional ceramics by most currently available analytical techniques. The present study is an analysis and optimization of the experimental conditions required to quantify the local nanoscale stoichiometry of single crystal yttrium barium copper oxide (YBCO) samples in three dimensions by atom probe tomography (APT). APT analysis required systematic exploration of a wide range of data acquisition and processing conditions to calibrate the measurements. Laser pulse energy, ion identification, and the choice of range widths were all found to influence composition measurements. The final composition obtained from melt-grown crystals with optimized superconducting properties was Y7.9Ba10.4Cu24.4O57.2.

Potential sources of compositional inaccuracy in the atom probe tomography of InxGa1-xAs

“…Since dissociation essentially leads to multi-hits, the presence of dissociation can be detected through a correlative analysis of the multi-hits, using an ioncorrelation histogram or Saxey map [24]. In line with previous studies [24], [25], [37], little evidence of dissociation was found for the data obtained on the LEAP 5000 XR. The reasons for this have been discussed in detail by Peng et.al.…”

Overcoming Challenges Associated with the Analysis of Nacre by Atom Probe Tomography

“…Secondly, it is possible that not all of the many peaks associated with molecular ions are correctly identified. Finally, no ranging standards are available for APT and the choice of range widths can significantly influence the measured chemical compositions, although to a smaller extent than ion identification (Pedrazzini et al 2017). It is possible that optimisation of the atom probe acquisition parameters may improve the accuracy of the compositional measurements.…”

Synthesis and in situ ion irradiation of A-site deficient zirconate perovskite ceramics

“…Perovskite structured materials have been widely investigated for various material applications, including as fuel cells, [1][2][3][4] dielectric resonators, [5][6][7] photovoltaics, 8,9 light emitting diodes, 10 lasers, 11,12 next generation nuclear fuels 13,14 and as hightemperature superconducting magnets. [15][16][17][18] Another potential application is in the immobilisation of nuclear waste streams as a host ceramic matrix. The namesake perovskite CaTiO 3 has been widely studied as a direct immobilisation matrix, including as a constituent of the SYNROC study, [19][20][21][22][23][24] while it is a commonly observed secondary actinide bearing phase when targeting zirconolite structured systems.…”