Mechanical Properties of Thermoelectric Ba^sub 8^Al^sub 15^Si^sub 31^ Clathrate Prepared by Combining Arc Melting and Spark Plasma Sintering Techniques

• Published in: Journal of electronic materials Vol. 45; no. 3; p. 1803
• Main Authors: Anno, Hiroaki, Ueda, Takahiro, Hirata, Shusaku, Kameyama, Tomoki, Iida, Tsutomu, Kogo, Yasuo
• Format: Journal Article
• Language: English
• Published: Warrendale Springer Nature B.V 01.03.2016
• Subjects: Electric power; Mechanical properties; Melting; Plasma sintering; Thermal energy
• ISSN: 0361-5235; 1543-186X
• DOI: 10.1007/s11664-015-4230-6

Issue Title: 2015 International Conference on Thermoelectrics. Guest Editors: Jihui Yang, Matt Beekman, Donald Morelli, James Salvador, David Singh, Hsin Wang, Emmanuel Guilmeau, Juri Grin, Bertrand Lenoir, Xinfeng Tang, Wenqing Zhang, Chunlei Wan, TieJun Zhu, Ryoji Funahashi, Takao Mori, Tsunehiro Takeuchi, Sabah Bux The mechanical properties (the elastic moduli, hardness, and fracture toughness) were investigated for polycrystalline Ba^sub 8^Al^sub 15^Si^sub 31^ clathrate as one of useful thermoelectric materials on a phonon glass and electron crystal concept. Samples were prepared by combining arc melting and spark plasma sintering techniques. The Young's modulus E = 96.88 GPa, shear modulus G = 38.61 GPa, bulk modulus K = 65.77 GPa, and Poisson's ratio ν = 0.2545 were calculated from longitudinal sound velocity v ^sub L^ = 6105 m/s and transverse sound velocity v ^sub T^ = 3503 m/s, measured by an ultrasonic test. The elastic constants c ^sub 11^ = 78.64 GPa, c ^sub 12^ = 40.03 GPa, and c ^sub 44^ = 38.61 GPa were calculated from E and G. The Vickers hardness HV and Young's modulus E were simultaneously determined to be 634 and 109.7 GPa, respectively, by a nanoindentation test. The fracture toughness K ^sub IC^ was determined to be 1.1 MPa m^sup 1/2^, which was comparable to typical values 1.1-1.2 MPa m^sup 1/2^ for thermoelectric silicide Mg^sub 2^Si, by a Vickers indentation fracture test.