CdSe x S y nanocrystals were synthesized in eight solvents that have different coordinating properties, trioctylphosphine oxide, trioctylphosphine, triphenylphosphine, oleylamine, hexadecylamine, dioctylamine, trioctylamine, and 1-octadecene at 230−300 °C. These nanocrystals exhibited high photoluminescence, which could be tuned over most of the visible region by changing the Se/S ratio or the solvent. The nanocrystals were characterized using UV−vis and IR spectroscopy, TEM, EDS, XRD, and NMR. 31P NMR and IR studies provided vital information about the nanocrystal surface capping ligands, indicating that those prepared in noncoordinating solvents were stabilized in solution mainly by oleic acid while those prepared in the coordinating solvents were stabilized mainly by solvent, phosphine and phosphine sulfide ligands, and some oleic acid. The hexagonal or cubic phase of these nanocrystals can be selectively prepared at temperatures as high as 300 °C by choosing the appropriate solvent.

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The addition of dysprosium oxide nanoparticles is shown to improve the critical current in perpendicular magnetic fields for second-generation (2G) wire formed by metal-organic deposition (MOD). Typical enhancements in J c are from 0.17 MA cm −2 to over 0.33 MA cm −2 at 77 K and B perp = 1.5 T. TEM analysis shows that we are introducing (Y, Dy) 2 O 3 nanoparticles with dimensions of 10-50 nm. A simple theoretical analysis shows that the maximum pinning effect for additions is expected at excess concentrations of approximately 70% DyO 1.5 , i.e. for YBa 2 Cu 3 O 7−δ + 0.7DyO 1.5 if the added nanoparticles are randomly dispersed and a strong pinning model is valid. An interesting feature is that the critical current in parallel field is reduced in these samples. We present evidence that shows this may be due to reduced planar defects in the YBCO.