Polarized Oxygen Kα and Copper Lα X-Ray Emission Spectroscopy of YBa2Cu3O7

1995 ◽  
Vol 50 (10) ◽  
pp. 935-941
Author(s):  
A. Kottmann ◽  
R. Siebinger ◽  
S. Steeb

Abstract The high temperature superconductor YBa2Cu3O7 is characterized by a very anisotropic structure. The electronic structure of this compound is studied using high resolution valence band spectroscopy within an electron probe microanalyzer. From single crystals and melt-textured specimens,orientation dependent Cu-Lα spectra are obtained using a beryl crystal. The Cu-Lα spectra with polarization parallel to the z-direction show a larger energetic breadth compared to those obtained with polarization perpendicular to z. This is caused by occupied Cu3d3z2-r2 like states, as could be shown by other workers using cluster calculations.With a chlinochlore crystal, the polarized O-Kα, spectra can be used to investigate the orientation of single crystal areas. The spectra map the bandlike O2p states. In contrast to the Cu-Lα spectra,the partial O -Kα spectra agree with band structure calculations in the local density approximation done by other workers.

1989 ◽  
Vol 44 (9) ◽  
pp. 780-784
Author(s):  
F. Burgäzy ◽  
C. Politis ◽  
P. Lamparter ◽  
S. Steeb

Abstract The measured O Kα X-ray emission spectrum of the high-Tc superconductor Bi2Sr2CaCu2O8-x is compared with a spectrum based on local density band structure calculations. By taking also into account the shape of the measured O 1s X-ray photoelectron spectrum an energy level diagram for the O 1s core-level binding energies of the three different oxygen sites is constructed. The O 1s binding energy in the Bi2O2-layers is found to be about the same as that one in the SrO-layers, whereas the binding energy in the CuO2-layers is lower by about 0.5 eV.


1999 ◽  
Vol 5 (S2) ◽  
pp. 78-79
Author(s):  
C. Merlet ◽  
X. Llovet ◽  
F. Salvat

Studies of x-ray emission from thin films on substrates using an electron probe microanalyzer (EPMA) provide useful information on the characteristics of x-ray generation by electron beams. In this study, EPMA measurements of multilayered samples were performed in order to test and improve analytical and numerical models used for quantitative EPMA. These models provide relatively accurate results for samples consisting of layers with similar average atomic numbers, because of their similar properties regarding electron transport and x-ray generation. On the contrary, these models find difficulties to describe the process when the various layers have very different atomic numbers. In a previous work, we studied the surface ionization of thin copper films of various thicknesses deposited on substrates with very different atomic numbers. In the present communication, the study is extended to the case of multilayered specimens.The studied specimens consisted of thin copper films deposited on a carbon layer which, in turn, was placed on a variety of single-element substrates, ranging from Be to Bi.


2004 ◽  
Vol 377 (1-2) ◽  
pp. 25-28 ◽  
Author(s):  
J. Manica ◽  
M. Abbate ◽  
J.E. Gayone ◽  
J.A. Guevara ◽  
S.L. Cuffini

2001 ◽  
Vol 56 (7) ◽  
pp. 620-625 ◽  
Author(s):  
Christian Kranenberg ◽  
Dirk Johrendt ◽  
Albrecht Mewis ◽  
Winfried Kockelmann

Abstract LaAlSi2 (a = 4.196(2), c = 11.437(7) Å; P3̄ml; Z = 2) was synthesized by arc-melting of preheated mixtures of the elements. The compound was investigated by means of X-ray methods and by neutron diffraction. The crystal structure can be described as a stacking variant of two different segments. The first one corresponds to the CaAl2Si2 structure type (LaAl2Si2), the second one with the A1B2 structure type (LaSi2). The segments are stacked along [001]. The electronic structure of the compound is discussed on the basis of LMTO band structure calculations.


1989 ◽  
Vol 114 ◽  
pp. 495-497 ◽  
Author(s):  
E.P. Domashevskaya ◽  
Yu.K. Timoshenko ◽  
V.A. Terekhov ◽  
E.N. Desyatirikova ◽  
E.Yu. Bulycheva ◽  
...  

2008 ◽  
Vol 78 (23) ◽  
Author(s):  
Catherine Guillot-Deudon ◽  
Sylvie Harel ◽  
Arezki Mokrani ◽  
Alain Lafond ◽  
Nicolas Barreau ◽  
...  

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