Raman-scattering study of the metal-insulator transition inBa1−xKxBiO3

1992 ◽  
Vol 46 (2) ◽  
pp. 1232-1235 ◽  
Author(s):  
S. Tajima ◽  
M. Yoshida ◽  
N. Koshizuka ◽  
H. Sato ◽  
S. Uchida
Keyword(s):  
Raman Scattering ◽  
Insulator Transition ◽  
Metal Insulator Transition ◽  
Metal Insulator ◽  
Scattering Study

scholarly journals Structural characterization of heat-treated activated carbon fibers

1992 ◽  
Vol 7 (7) ◽  
pp. 1788-1794 ◽  
Author(s):  
A.M. Rao ◽  
A.W.P. Fung ◽  
M.S. Dresselhaus ◽  
M. Endo
Keyword(s):  
Heat Treatment ◽  
Activated Carbon ◽  
Raman Scattering ◽  
Carbon Fibers ◽  
Insulator Transition ◽  
Activated Carbon Fibers ◽  
Metal Insulator Transition ◽  
Metal Insulator ◽  
Sequence Of Events ◽  
Heat Treated

Raman scattering, x-ray diffraction, and BET measurements are used to study the effect of heat treatment on the microstructure of activated carbon fibers (ACFs) and to correlate the structural changes with the metal-insulator transition observed in the electronic transport properties of heat-treated ACFs. A sequence of events is identified, starting with desorption, followed by micropore collapse plus the stacking of basic structural units in the c-direction, and ending up with in-plane crystallization. The graphitization process closely resembles that depicted by Oberlin's model, except that the final material at high-temperature heat treatment remains turbostratic. Because the metal-insulator transition was observed to occur at heat-treatment temperature THT ≃ 1200 °C, which is well below the THT value (2000 °C) for in-plane crystallization, we conclude that this electronic transition is not due to in-plane ordering but rather to the collapse of the micropore structure in the ACFs. Raman scattering also provides strong evidence for the presence of local two-dimensional graphene structures, which is the basis for the transport phenomena observed in heat-treated ACFs.

scholarly journals A Brillouin scattering study of La0.77Ca0.23MnO3 across the metal–insulator transition

2004 ◽  
Vol 16 (24) ◽  
pp. 4381-4390 ◽  
Author(s):  
Md Motin Seikh ◽  
Chandrabhas Narayana ◽  
L Sudheendra ◽  
A K Sood ◽  
C N R Rao
Keyword(s):  
Brillouin Scattering ◽  
Insulator Transition ◽  
Metal Insulator Transition ◽  
Metal Insulator ◽  
Scattering Study

Fermi-surface reconstruction close to a pressure-induced metal-insulator transition

2004 ◽  
Vol 114 ◽  
pp. 277-281 ◽  
Author(s):  
J. Wosnitza ◽  
J. Hagel ◽  
O. Stockert ◽  
C. Pfleiderer ◽  
J. A. Schlueter ◽  
...  
Keyword(s):  
Fermi Surface ◽  
Surface Reconstruction ◽  
Insulator Transition ◽  
Metal Insulator Transition ◽  
Metal Insulator ◽  
Fermi Surface Reconstruction
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