Nanocrystallization tuning of structural, thermoelectric and electrical properties of SrTiO₃-doped vanadate glasses

Abstract

Abstract Glass-ceramic nanocrystals (GCNs) were obtained by annealing parent SrTiO 3 -V 2 O 5 (SV) glasses prepared using the melt-quenching technique at the crystallization temperature, T c . The amorphous nature and glassy behavior of the quenched glasses were confirmed by XRD, DSC and FTIR spectroscopy. In the heat-treated samples, the crystal size was found to range from 40 to 80 nm for all studied samples. It was observed that as the SrTiO 3 content in the GCNs increased, density (d) steadily rose. The change of vanadium ions concentration(C) has the predominant role for changing Seebeck coefficient in both glass and GCNs samples. The nanocrystallization process at temperatures close to the onset of T c , lasting for one hour, notably increased the electronic conductivity of the initial glasses. Consequently, the modification in nanostructure resulted in enhanced conductivity. In comparison to the original glasses, the final materials demonstrated significantly improved electrical conductivity. The accumulation of V 4+ -V 5+ pairs at the formed interlayer zones between nanocrystallites and the glassy phase is accountable for electron hopping in the current system, which is markedly higher than in the glassy matrix. The formed nanocrystallites play a crucial role in augmenting the conductivity of such nanomaterials. The maximum obtained value of the power factor (PF) is 0.9 × 10 −4 mW/mk 2 for the glass sample (x = 20) reflecting a very low thermoelectric power conversion efficiency while in GCNs, the PF values were well-enhanced to 0.6 mW/m.K 2 at x = 20.