The Effect of Alkaline Earth (Ba, Sr and Ca) Doped Iron Bismuth Glasses on the Structural, Thermoelectric and Electrical Properties

Glasses with nominal composition 70Bi2O3–30Fe2O3 and 10X–60Bi2O3–30Fe2O3 (mol%); (X = Ba, Sr and Ca) were prepared by the conventional melt quenching technique. X-ray diffraction and differential scanning calorimeter confirm the amorphous nature of the glass samples. The iron-bismuth glass shows good solubility of alkaline earth elements ions. In temperatures range of 310–450 K, the dc conductivity of the glass samples containing alkaline earth elements enhanced. Glass sample containing Sr shows interesting electrical properties. All glass samples showed a transition from negative to positive Seebeck coefficient, this means that the conduction is mixed of electrons and holes charge carriers. The conduction mechanism of all samples obeys non-adiabatic small polaron hopping model of electron between iron ions. The calculated small polaron coupling constant, (γp) was found to be in the range of 10.25–17.28. Also, the calculated hopping mobility (μ) and carrier density (Nc) of glasses were in the range of 4.65 $$\times {10}^{- 7}$$ to 4.11 $$\times {10}^{-3},\left({\mathrm{cm}}^{2}\,{\mathrm{V}}^{-1}\,{\mathrm{s}}^{-1}\right)$$ and 0.029–10 $$({\times {10}^{17}\,\mathrm{cm}}^{-3})$$ at 333 K, respectively. The conductivity of the present glasses was primarily determined by hopping carrier mobility.