Hardness and fracture toughness of thermoelectric La_(3-x)Te_4

摘要

Lanthanum telluride (La_(3-x)Te_4) is a state-ofthe- art n-type high temperature thermoelectric material that behaves as a weak and brittle ceramic. Vickers microindentation hardness testing was explored as a rapid analysis technique to characterize the mechanical properties of this material. An indentation size effect was observed with hardness values ranging from 439 ± 31 kgf/mm~2 (0.01 kgf/ 10 s contact time) to 335 ± 6 kgf/mm~2 (0.5 kgf/10 s contact time). The Vickers indentation fracture toughness, K_(VIF), based on measurements of crack lengths emanating from the corners of the Vickers indents was 0.70 ± 0.06 MPa m~(1/2).