ISSN:
1573-4803
Source:
Springer Online Journal Archives 1860-2000
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
Abstract The semiconducting system 50 mol% PbO-V2O5 has been studied by electron spin resonance (ESR) in the temperature range 150 to 675 K. Depending on the cooling rate, this system can be obtained from the melt as an amorphous phase, as polycrystalline leadmetavanadate (PbV2O6), or as two different mixtures containing polycrystalline and amorphous phases. In all these materials the ratio V4+/Vtot has been measured by wet analysis showing that the V4+ concentration is nearly constant. It has been possible to show that the appearance of very different ESR line-shapes for the various materials is due to the difference in the hopping rate of the charge carriers. In particular the presence of a well-defined hyperfine structure is characteristic of the amorphous phase, in which the mobility of the charge carriers is lowered by the presence of a termW D in the expression of the hopping rate. The lead-metavanadate ESR spectrum shows the presence of two lines of different widths; this fact has been explained assuming the presence of two distinct jumping rates. No temperature variation of the spectra has been observed at low temperatures. The high temperature spectra have permitted us to follow the thermal evolution of the system.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01203486
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