ZIB

Hits per page

hits 1 - 2 | 2 hits

Sorting

Electronic Resource

Superconductivity above 100 K in compounds containing Hg (1995)

Osofsky, M. S. ; Lechter, W. L. ; Toth, L. E. ; [et al.]

Springer

Journal of superconductivity 8 (1995), S. 511-514

add to mindlist on the mindlist

Details

ISSN: 1572-9605

Keywords: superconductivity ; cuprate ; Hg ; Tl

Source: Springer Online Journal Archives 1860-2000

Topics: Electrical Engineering, Measurement and Control Technology , Physics

Notes: Abstract The results of studies of new Hg based cuprate superconductors are reported. Several members of a new family of (Hg,Tl)(Ba,Sr)Can−2CunOx high temperature superconductors have been synthesized. These compounds, which are analogs to the Hg-Ba-Ca- and Tl-Ba-Ca-layered cuprates, are multi-phased and have superconducting transition temperatures above 100 K. Incorporation of Hg appears to stabilize several of the Tl-compounds, including a double layer. Tl/Sr system, in a manner similar to the role that Pb plays in the Tl/Sr- and Bi/Sr-systems. It has been suggested that recent reports of resistive Tc's above 200 K in Hg based samples are due to the presence of free Hg. Magnetization measurements of such a sample confirm this hypothesis.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00722843

Permalink

Library	Location	Call Number	Volume/Issue/Year	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

Electronic Resource

X-ray fluorescence analysis of tree rings (1991)

Gilfrich, J. V. ; Gilfrich, N. L. ; Skelton, E. F. ; [et al.]

New York, NY [u.a.] : Wiley-Blackwell

X-Ray Spectrometry 20 (1991), S. 203-208

add to mindlist on the mindlist

Details

ISSN: 0049-8246

Keywords: Chemistry ; Analytical Chemistry and Spectroscopy

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Physics

Notes: X-ray fluorescence analysis was applied to the determination of the concentration of trace elements in the growth rings of trees. Some of these mineral elements can affect the growth and development of the plant. The results of the analytical measurements can provide information concerning the geochemical and atmospheric environment to which the tree has been exposed. It has been demonstrated that conventional x-ray fluorescence equipment is adequate to perform such measurements but, more important, the high intensity available from synchrotron radiation is an ideal source to probe the spatial variation in the low-level concentrations which can be transposed to an absolute temporal scale knowing the history of the tree. The ability to aperture or focus the synchrotron radiation to submillimeter size allows several points within individual rings to be analyzed, permitting a study of differences within a single growing season.Concentrations of mineral elements were determined in two types of tree samples, a cross-section of the trunk of a small sassafras tree and an incremental core from a red oak. Two experimental arrangements were employed, a special energy-dispersive x-ray analyzer with a primary beam size of 0.5 mm and a beam line at the National Synchrotron Light Source where the radiation was focused and apertured to 50 μm × 1 mm. Concentrations as low as 1 ppm were determined for nine elements. Major year-to-year variations were observed, implying that cross-ring elemental migration is slow (possibly negligible). The x-ray technique is fast and non-destructive, permitting the sample to be retained for additional studies.

Additional Material: 8 Ill.