Application of Some Techniques Using Synchrotron Radiation to the Study of Promising SrTiO 3 –TiO 2 Composite Thermoelectric Ceramics

The paper presents the results of studies of SrTiO 3 –TiO 2 biphase ceramics, which was previously proposed as a promising n-type thermoelectric material, carried out using synchrotron radiation techniques at the research equipment of the Shared Research Center “Siberian Synchrotron and Terahertz Radiation Center”. In particular, the in-situ heating X-ray diffraction method demonstrated that the reaction between the powder components SrCO 3 (strontianite) and TiO 2 (anatase) to produce SrTiO 3 (tausonite) was not the driving force in producing ceramics by spark plasma sintering of the reaction mixture. For two spectral methods, X‑ray luminescence and XANES spectroscopy, the spectrum of biphase ceramics was compared with the model spectrum obtained from the spectra of monophase ceramics as comparison samples. The method of X-ray luminescence revealed a shift to the high-energy region and a narrowing of the spectrum of biphase ceramics, which may indicate dimensional quantization (the presence of two-dimensional electron gas) in the system. The XANES spectrum of biphase ceramics reveals changes in the region in which its shape may significantly depend on the symmetry of the nearest Ti 4+ atoms. However, it is difficult to interpret these data without numerical simulation.