Sedat Ballıkaya-Istanbul University-Cerrahpaşa, Faculty of Engineering,EngineeringScienceDept,TURKEY скачать в хорошем качестве

Sedat Ballıkaya-Istanbul University-Cerrahpaşa, Faculty of Engineering,EngineeringScienceDept,TURKEY

Titled: NEW METHODOLOGY FOR ENHANCING THERMOELECTRIC PERFORMANCE OF BiSbTe COMPOUNDS; DOPING WITH HEAVY AND LARGE ATOMIC RADIUS DISCREPANCY METAL ATOMS Abstract: In this work, the structural and transport properties of BiSbTe compounds in which Boron, Barium and Ytterbium is replaced with Bi atoms, were investigated. B, Ba and Yb doped both Bi2-xTe3 and Sb1.5Bi0.5-xTe3 (x=0-0.5) were synthesized successfully via fast and cost effective process, mechanically alloying followed by cold press and sintering method. Structural properties were examined based on PXRD, SEM analysis and transport data were obtained by Seebeck coefficient, electrical conductivity and thermal conductivity measurements. PXRD analysis confirm that all samples except samples included x=0.5 consist with literature and show the nature of Bi2Te3 and Sb2Te3 crystal structure. SEM analysis show that texturing and crystallization increases with increasing content of B, Ba, and Yb. The unit cell volume is expanding with Ba and Yb doping while it is shrinking with B doping in BiSbTe compounds likely due to large discrepancy of atomic radius between Bi and B, Ba and Yb atoms. Seebeck coefficient decreases and electrical conductivity increases with increasing content of doping in BiSbTe due electron donation by B,Ba and Yb atoms. Thermal conductivity suppressing with content of B, Ba and Yb might be due to increasing point defect scattering. The maximum ZT value of 0.9 and 1.3 were obtained in Bi0.1Bi1.9Te3 and Sb1.5B0.1Bi0.4Te3 compounds at 373 K. The structural and transport data indicate that Boron is more effective dopant for BiSbTe compounds and small amount of any metallic dopant with high electronegativity value can enhance ZT value at least 15% for BiSbTe compound in compare to pristine ones. All results indicate that replacing Bi atoms with metal atoms having high electronegative value and atomic radius discrepancy is effective way to manipulate transport properties and enhance the thermoelectric figure of merit of BiSbTe compounds [1-3]. References: [1]B. Hamawandi et al., .Appl. Sci., 10, 1178 (2020). [2]S. Ballikaya et. al., J. Solid State Chem.; 273, 122–7 (2019). [3]C. Uher, Material Aspect for Thermoelectricity, CRC Press (2017).