Determination of oxygen contents and cation valences in the superconducting bismuth and thallium cuprates

1995 ◽  
Vol 8 (1) ◽  
pp. 31-35 ◽  
Author(s):  
A. Fukuoka ◽  
M. Karppinen ◽  
M. Itoh ◽  
K. Hamada ◽  
H. Yamauchi
Keyword(s):  
Thallium Cuprates

In defense of the bromine method for the determination of hole concentration in superconducting thallium cuprates

1992 ◽  
Vol 96 (2) ◽  
pp. 468-469 ◽  
Author(s):  
J. Gopalakrishnan ◽  
R. Vijayaraghavan ◽  
R. Nagarajan ◽  
C. Shivakumara
Keyword(s):  
Hole Concentration ◽  
Thallium Cuprates

TlBa2NdCu2O7 AND TlBa2YCu2O7 TWO NON-SUPERCONDUCTIVE OXIDES WITH THE “1212” STRUCTURE

1989 ◽  
Vol 03 (01) ◽  
pp. 93-99 ◽  
Author(s):  
C. MARTIN ◽  
D. BOURGAULT ◽  
C. MICHEL ◽  
M. HERVIEU ◽  
B. RAVEAU
Keyword(s):  
Diffraction Study ◽  
Powder Diffraction ◽  
Rock Salt ◽  
Close Relationships ◽  
Double Perovskite ◽  
X Ray ◽  
Thallium Cuprates ◽  
Significant Difference ◽  
Oxygen Atoms

Two new thallium cuprates isostructural with the “1212” superconductors were synthesized. These materials do not exhibit any superconductivity in spite of the presence of Tl(III), contrary to the oxides such as Tl 2 Ba 2 CaCu 2 O 8 or Tl 2 Ba 2 Ca 2 Cu 3 O 10. Their X-ray powder diffraction study confirms their close relationships with the superconductor TlBa 2 CaCu 2 O 7, i.e., their structure is built up from distorted double rock salt-type layers [(TIO) (BaO)] intergrown with oxygen deficient double perovskite layers [ BaY ( CuO 2.5)2] or [ BaNd ( CuO 2.5)2]. Although the determination of the positions of the oxygen atoms cannot be considered as accurate, one significant difference with respect to TlBa 2 CaCu 2 O 7 must be pointed out: the oxygen atoms forming the basal planes of the CuO 5 pyramids are brought closer together along c, leading to an almost cubic environment for Y and Nd, whereas the CaO 8 prisms are elongated along c in the thallium superconductors.

A novel method for the determination of the oxygen content of superconducting thallium cuprates

1993 ◽  
Vol 6 (4) ◽  
pp. 265-268 ◽  
Author(s):  
M Karppinen ◽  
A Fukuoka ◽  
T Kaneko ◽  
H Yamauchi
Keyword(s):  
Oxygen Content ◽  
Thallium Cuprates ◽  
Novel Method

Determination of Average Valences of Copper and Thallium Separately in the Superconducting Thallium Cuprates

1993 ◽  
pp. 283-286
Author(s):  
A. Fukuoka ◽  
M. Karppinen ◽  
M. Ito ◽  
K. Hamada ◽  
H. Yamauchi
Keyword(s):  
Thallium Cuprates

Determination of hole concentration in superconducting thallium cuprates

1991 ◽  
Vol 93 (1) ◽  
pp. 272-275 ◽  
Author(s):  
J. Gopalakrishnan ◽  
R. Vijayaraghavan ◽  
R. Nagarajan ◽  
C. Shivakumara
Keyword(s):  
Hole Concentration ◽  
Thallium Cuprates

Galactic orbits of stars

1966 ◽  
Vol 25 ◽  
pp. 93-97
Author(s):  
Richard Woolley
Keyword(s):  
Globular Cluster ◽  
Potential Field ◽  
High Velocity ◽  
Velocity Vector ◽  
Variable Stars ◽  
The Sun ◽  
Proper Motions ◽  
Rr Lyrae ◽  
The Galaxy

It is now possible to determine proper motions of high-velocity objects in such a way as to obtain with some accuracy the velocity vector relevant to the Sun. If a potential field of the Galaxy is assumed, one can compute an actual orbit. A determination of the velocity of the globular clusterωCentauri has recently been completed at Greenwich, and it is found that the orbit is strongly retrograde in the Galaxy. Similar calculations may be made, though with less certainty, in the case of RR Lyrae variable stars.

Distance to SN 1987A and the LMC

1999 ◽  
Vol 190 ◽  
pp. 549-554
Author(s):  
Nino Panagia
Keyword(s):  
Angular Size ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Light Curves ◽  
Distance Modulus ◽  
Absolute Size ◽  
Sn 1987A

Using the new reductions of the IUE light curves by Sonneborn et al. (1997) and an extensive set of HST images of SN 1987A we have repeated and improved Panagia et al. (1991) analysis to obtain a better determination of the distance to the supernova. In this way we have derived an absolute size of the ringRabs= (6.23 ± 0.08) x 1017cm and an angular sizeR″ = 808 ± 17 mas, which give a distance to the supernovad(SN1987A) = 51.4 ± 1.2 kpc and a distance modulusm–M(SN1987A) = 18.55 ± 0.05. Allowing for a displacement of SN 1987A position relative to the LMC center, the distance to the barycenter of the Large Magellanic Cloud is also estimated to bed(LMC) = 52.0±1.3 kpc, which corresponds to a distance modulus ofm–M(LMC) = 18.58±0.05.

International determination of the total motion of the pole

1961 ◽  
Vol 13 ◽  
pp. 29-41
Author(s):  
Wm. Markowitz
Keyword(s):  
Secular Motion ◽  
The Future

A symposium on the future of the International Latitude Service (I. L. S.) is to be held in Helsinki in July 1960. My report for the symposium consists of two parts. Part I, denoded (Mk I) was published [1] earlier in 1960 under the title “Latitude and Longitude, and the Secular Motion of the Pole”. Part II is the present paper, denoded (Mk II).

Time and Latitude in South Africa

1972 ◽  
Vol 1 ◽  
pp. 27-38
Author(s):  
J. Hers
Keyword(s):  
South Africa ◽  
Cape Town ◽  
Astronomical Observations ◽  
Royal Observatory ◽  
The Republic ◽  
Astronomical Determination ◽  
Limited Accuracy ◽  
Better Than

In South Africa the modern outlook towards time may be said to have started in 1948. Both the two major observatories, The Royal Observatory in Cape Town and the Union Observatory (now known as the Republic Observatory) in Johannesburg had, of course, been involved in the astronomical determination of time almost from their inception, and the Johannesburg Observatory has been responsible for the official time of South Africa since 1908. However the pendulum clocks then in use could not be relied on to provide an accuracy better than about 1/10 second, which was of the same order as that of the astronomical observations. It is doubtful if much use was made of even this limited accuracy outside the two observatories, and although there may – occasionally have been a demand for more accurate time, it was certainly not voiced.

Large-scale Motion of Solar Filaments

2000 ◽  
Vol 179 ◽  
pp. 205-208
Author(s):  
Pavel Ambrož ◽  
Alfred Schroll
Keyword(s):  
Magnetic Flux ◽  
Proper Motion ◽  
Time Scale ◽  
Large Scale ◽  
Accuracy Of Measurements ◽  
Solar Filaments ◽  
General Movement ◽  
Scale Motion ◽  
Velocity Scatter

AbstractPrecise measurements of heliographic position of solar filaments were used for determination of the proper motion of solar filaments on the time-scale of days. The filaments have a tendency to make a shaking or waving of the external structure and to make a general movement of whole filament body, coinciding with the transport of the magnetic flux in the photosphere. The velocity scatter of individual measured points is about one order higher than the accuracy of measurements.

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