Year: 2018
Type: article
Abstract: A series of Bi 1−x Sr x MnO 3 (x = 0.40, 0.45, 0.50, 0.55) samples labeled as BSMO040, BSMO045, BSMO050, and BSMO055, respectively, have been fabricated by the modified solid-state reaction method. The crystal structural, microstructures, and chemical states of the elements and the thermoelectric properties were investigated with respect to the partial substitution of Sr 2+ for Bi 3+ . The samples were characterized by x-ray diffraction (XRD) at 723 K, scanning electron microscopy (SEM), and x-ray photoelectron spectroscopy (XPS). Moreover, their electrical conductivities ( σ ), Seebeck coefficients ( S ), and thermal conductivities ( κ ) were determined. All the samples exhibited orthorhombic structure. The partial substitution of Sr 2+ for Bi 3+ caused valence shift of some Mn ions from +3 to +4 to maintain electric charge balance. The change in electric charge led to an increase in electron concentration, and thus, the electrical conductivity as well as the absolute value of Seebeck coefficient increased. Consequently, the power factor also increased. The highest power factor (0.3 × 10 −4 Wm −1 K −1 ) was obtained for BSMO055 at 1023 K. Moreover, the highest dimensionless figure-of-merit ( ZT ) obtained in this study was 0.015 for BSMO055 at 1073 K. It can be concluded that the partial substitution of Sr 2+ for Bi 3+ in the Bi 1−x Sr x MnO 3 samples (x = 0.40, 0.45, 0.50, and 0.55) improved the thermoelectric properties effectively.
Source: Materials Research Express
Language: English
Subfield: Materials Chemistry
Field: Materials Science
Domain: Physical Sciences
Open Access status: bronze
OpenAlex ID: W2795723574