Application of Some Techniques Using Synchrotron Radiation to the Study of a Promising Composite Thermoelectric Material SrTiO₃–TiO₂

Abstract

The results of a study of biphase ceramics SrTiO3–TiO2, previously proposed as a promising n-type thermoelectric material, obtained using synchrotron radiation techniques at the shared research center “Siberian Synchrotron and Terahertz Radiation Center”, are presented. In particular, it has been demonstrated by in-situ heating X-ray diffraction that the reaction between the powder components SrCO3 (strontianite) and TiO2 (anatase) to obtain SrTiO3 (tausonite) is not the driving force in the preparation of ceramics by spark plasma sintering of the reaction mixture. For two spectral methods – X-ray luminescence and XANES spectroscopy, the spectrum of biphasic ceramics was compared with a model spectrum obtained from the spectra of single-phase ceramics as reference samples. The X-ray luminescence method revealed a shift to the high-energy region and a narrowing of the spectrum of biphase ceramics, which may indicate size quantization (the presence of a two-dimensional electron gas) in the system. Changes were found in the XANES spectrum of biphase ceramics in the region in which its shape can significantly depend on the symmetry of the nearest environment of Ti4+ atoms. However, it is difficult to interpret these data without numerical simulation.