122nd General Meeting of the KCS

Type Poster Presentation
Area Inorganic Chemistry
Room No. Grand Ballroom
Time 10월 19일 (금요일) 11:00~12:30
Code INOR.P-34
Subject Zintl Phase Thermoelectric Material with the n-type dopant: Ca3.40(3)Yb1.48Pr0.12Al2Sb6
Authors Seungeun Shin, Tae-Soo You*
Department of Chemistry, Chungbuk Natioanl University, Korea
Abstract Thermoelectric (TE) materials and the devices based on these materials have been considered as one of the smartest approaches to reduce global energy consumption by recovering the wasted heat from various heat sources and converting it into electricity. Recently, the A5M2Pn6 (A = Ca, Sr, Eu, Yb, M = Al, Ga, In) series has been extensively investigated as Zintl phase TE materials, and two major structure types have been identified: the Ba5Al2Bi6-type having metallic behavior and the Ca5Ga2Sb6-type showing the semiconducting behavior. To investigate the effect of cationic substitution and n-type doping for TE properties of the Ca5Ga2Sb6-type compounds, a quinary Zintl phase Ca3.40(3)Yb1.48Pr0.12Al2Sb6 was successfully synthesized by arc-melting, and its crystal structure was characterized by both powder and single-crystal X-ray diffractions. It is already known that in the Ca5-xYbxAl2Sb6 (1.0 ≤ x ≤ 5.0) system, the Ca-rich compounds adopt the Ca5Ga2Sb6-type structure through the post heat treatment. Nevertheless, the title compound adopted the Ba5Al2Bi6-type with the orthorhombic space group Pbam (Z = 2, Pearson Code oP26) even after the post heat treatment despite of its Ca-rich composition. According to the SXRD result, the symmetrically independent cationic sites contain a Ca2+/Yb2+ mixed-occupation with various mixed ratios. In particular, one cationic site additionally contains the n-type dopant Pr3+. Based on the deviation from the previously reported structural transformation trend, to understand the difference induced by n-type doping, a series of theoretical calculations using three different hypothetical structural models by tight-binding linear muffin-tin orbital method were performed and the results are thoroughly analyzed.
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