Structure and properties of a novel fulleride Sm6C60

A novel fulleride Sm6C60 has been synthesized using high temperature solid state reaction. The Rietveld refinement on high resolution synchrotron X-ray powder diffraction data shows that Sm6C60 is isostructural with body-centered cubic A6C60 (A=K, Ba). Raman spectrum of Sm6C60 is similar to that of Ba6C60, and the frequencies of two Ag modes in Sm6C60 are nearly the same as that of Ba6C60, suggesting that Sm is divalent and hybridization between C60 molecules and the Sm atom could exist in Sm6C60. Resistivity measurement shows a weak T-linear behavior above 180 K, the transport at low temperature is mainly dominated by granular-metal theory.Comment: 9 pages, 3 figures, submitted to Phys. Rev. B (March 12, 1999

Superconducting Tl-Ba-Ca-Cu-O films by sputtering

Superconducting Tl-Ba-Ca-Cu-O thin films 0.2–1.0 µm thick have been prepared on MgO(100) and SrTiO3 (100) substrates by dc diode sputtering using a single oxide target. Films containing primarily the Tl2Ba2Ca1Cu2O8 phase were obtained with a Tc (R =0) at 102 K and a transport Jc of 104 A/cm2 at 90 K. For the nearly pure phase Tl2Ba2Ca2Cu3O10 films, the Tc\u27s (R =0) are higher at 116 K and the transport Jc\u27s at 100 K are of 105 A/cm2. Both types of films show a strong preferred orientation with the c axis perpendicular to the film plane. The rocking curve of the Tl2Ba2Ca2Cu3O10 films is 0.32° wide and the typical grain size is over 10 µm

Superconducting Tl-Ba-Ca-Cu-O films by sputtering

Superconducting Tl-Ba-Ca-Cu-O thin films 0.2–1.0 µm thick have been prepared on MgO(100) and SrTiO3 (100) substrates by dc diode sputtering using a single oxide target. Films containing primarily the Tl2Ba2Ca1Cu2O8 phase were obtained with a Tc (R =0) at 102 K and a transport Jc of 104 A/cm2 at 90 K. For the nearly pure phase Tl2Ba2Ca2Cu3O10 films, the Tc\u27s (R =0) are higher at 116 K and the transport Jc\u27s at 100 K are of 105 A/cm2. Both types of films show a strong preferred orientation with the c axis perpendicular to the film plane. The rocking curve of the Tl2Ba2Ca2Cu3O10 films is 0.32° wide and the typical grain size is over 10 µm

Dynamics of line defects in nematic liquid crystals

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Diffraction Symmetry in Crystalline, Close-Packed C60

We have grown crystals of the carbon structure C60 by sublimation. In contrast to solution-grown crystals, the sublimed crystals have long range order with no evidence of solvent inclusions. Sublimed C60 forms three dimensional, faceted crystals with a close-packed, face-centered cubic unit cell. We have refined a crystal structure using the "soccer ball" model of the C60 molecule. The results indicate that the C60 molecule has the expected spherical shape, however the data are not sufficiently accurate to unambiguously determine atomic positions

Novel A15 phase in barium-doped fullerite

A new stable compound Ba3C60 is reported in the Ba-C60 phase diagram. Rietveld refinement of x-ray powder diffraction data shows that this compound has the A15 structure with a lattice constant of 11.34. The Pm3̄n space group implies a perfect alternating orientational order for the C60 molecules, not previously observed in doped fullerite structures. The relative stability of the A15 phase over the fully intercalated fcc structure can be explained by a simple model involving the Madelung energy differences, orientation dependence of the C60-cation interaction energy, and distortion-induced relaxational energy gains