Growth and characterization of superconductive Nd_2‐xCe_xCuO_4‐y single crystals

Abstract

Nd2‐xCexCuO4‐y single crystals with different x values have been successfully grown by Traveling Solvent Floating Zone method (TSFZ). Electronic properties of Nd2‐xCexCuO4‐y single crystals with various x have been studied in detail. The results show that superconductivity can be found in crystals with x > 0.1 (0.13‐0.18) directly grown at oxygen‐reduced atmosphere without post‐annealed, while no superconductivity appears in crystals with x < 0.1 at the same atmosphere. It is also found that, the segregation coefficient of Ce is determined to be 0.946 and transition temperature Tc (onset) reaches maximum value of 23.5 K at nominal composition x = 0.165. With further increase of Ce concentration, transition temperature of single crystals declines due to the precipitation of secondary Phases. In addition, the variation of lattice constants of Nd2‐xCexCuO4‐y single crystals with different x is also given. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Characterization of Cuprate based Cathode Structures by AC Impedance

“…In general this matches published patterns for tetragonal NCCO, however some small impurity peaks are also evident. These have been matched to phases of Ce 1-x Nd x O 2-y which some literature does suggest may form as a precipitate phase above the solubility limit of the Ce in the cuprate at x=0.18 (9). It is known from previous work that the presence of this precipitate phase does have an impact on the electrical behaviour of the cuprate, with these specimens exhibiting a semiconducting behaviour across the entire temperature range form room temperature to 1000°C and no metallic transition at intermediate temperatures (1).…”

Preparation and Properties of (Ce0.4La0.2Pr0.2Nd0.2)B6 Single‐Crystal by the Optical Float‐Zone Traveling Solvent Technique

“…Optical float‐zone traveling solvent technique can produce a stable morphology of the solidification interface, leading to a high quality of crystal growth . In order to effectively reduce the impurities of the sample as much as possible, two times growth of the floating‐zone melting were used to prepare the (Ce 0.4 La 0.2 Pr 0.2 Nd 0.2 )B 6 crystal, and especially for the second crystal growth, the growth rate must be lower than 10 mm/h.…”

Initial Characterisation of Cerium Doped Neodymium Cuprates for Solid Oxide Fuel Cell Applications

“…In general these match published patterns for tetragonal NCCO, however some small impurity peaks are also evident. These have been matched to phases of Ce 1-x Nd x O 2-y which some literature does suggest may form as a precipitate phase (6). Taking the assumption that the effect of this phase on the overall conductivity will depend on the relative amounts of the impurity versus the target phase and as the level of impurity phase appeared to be both small and comparable in each composition it was felt that any impact on findings for this initial study would be minimal, however the effects of this phase on performance will be investigated in more detail in future studies.…”