Behavior of Ag admixtures in Sb{sub 2}Te{sub 3} and Be{sub 2}Te{sub 3} single crystals
- Czech Academy of Sciences, Prague (Czech Republic)
- Univ. of Pardubice (Czech Republic). Faculty of Chemical Technology
- Czech Academy of Sciences, Prague (Czech Republic). Inst. of Inorganic Chemistry
Single crystals of Sb{sub 2}Te{sub 3} doped with Ag (c{sub Ag} = (0--9) {times} 10{sup 19} cm{sup {minus}3}) were prepared from the melt Sb{sub 2{minus}x}Ag{sub x}Te{sub 3} (denoted by a) or the melt Sb{sub 2}Ag{sub x}Te{sub 3} (denoted by b). The reflectivity in the IR region, electrical conductivity, and Hall coefficient were determined for these crystals. From the reflection spectra values of the high-frequency dielectric constant, optical relaxation time, and plasma resonance frequency were obtained for crystals with various Ag contents. The dependencies of the real ({var_epsilon}{sub 1}) and imaginary ({var_epsilon}{sub 2}) parts of the dielectric function and the imaginary part of the energy loss function (Im({minus}1/{var_epsilon})) on the wavenumber were also determined. From the {var_epsilon}{sub 2}(v) dependence at room temperature, it was concluded that in Sb{sub 2}Te{sub 3}(Ag) crystals the scattering mechanism of free carriers on the acoustical phonons prevails, but the participation of scattering on ionized impurities is also probable. The a- and b-type crystals of Sb{sub 2}Te{sub 3}(Ag) manifested practically the same values of transport coefficients and optical properties in the IR region. The determined values of the Hall coefficient showed that Ag atoms doping the Sb{sub 2}Te{sub 3} crystal structure behave as acceptors. The different behavior of Ag atoms in Sb{sub 2}Te{sub 3} and Bi{sub 2}Te{sub 3} crystals is probably associated with different parameters of the chemical bonds in these crystals, which is supported by the results of a semiempirical calculation.
- OSTI ID:
- 305389
- Journal Information:
- Journal of Solid State Chemistry, Vol. 140, Issue 1; Other Information: PBD: Oct 1998
- Country of Publication:
- United States
- Language:
- English
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