Heat conductivity of La1−xSrxMnO3 surface layers
| Autor: | Azza Ahmed, K. Bärner, U. Sondermann, A. Kattwinkel, I. El-Kassab, P. Mandal |
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| Rok vydání: | 2001 |
| Předmět: |
Materials science
Number density Condensed matter physics 02 engineering and technology Atmospheric temperature range 021001 nanoscience & nanotechnology Condensed Matter Physics 01 natural sciences Electronic Optical and Magnetic Materials Tunnel effect Thermal conductivity Seebeck coefficient 0103 physical sciences Thermoelectric effect Surface layer Electrical and Electronic Engineering 010306 general physics 0210 nano-technology Stoichiometry |
| Zdroj: | Physica B: Condensed Matter. 305:233-241 |
| ISSN: | 0921-4526 |
| DOI: | 10.1016/s0921-4526(01)00618-4 |
| Popis: | Using the transient thermoelectric effect (TTE), we have measured the thermoelectric power S(T) and the heat conductivity κ(T) of La1−xSrxMnO3 ceramic surface layers with nominal compositions x=0.075, 0.1, 0.15, 0.2 and 0.3 in the temperature range 50–340 K. Except for a shift in the characteristic temperatures, the surface layer S(T) is still similar to the bulk thermopower while the heat conductivity κ(T) is markedly different, even changing the slope at intermediate temperatures. As S is less structure sensitive than κ, we relate these differences to an increased number density of defects near the surface. In particular, a stoichiometry gradient close to the surface and oxygen vacancy related (two level tunneling-) modes are indicated. In addition, new S and κ data are presented for lower doping, i.e. x=0.075 and 0.1. |
| Databáze: | OpenAIRE |
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