Microstructural characterization of ultrarapid quenched bismuth and antimony tellurides alloys

Bi2-xSbxTe3 alloys were fabricated using the ultrarapid quenching process route, the quenching rate bring of 10(6) K/s. The materials were obtained in the shape of foils with a thickness varying from 10 to 60 mum. The microstructural study evidenced a fine grain microstructure with a grain size of tens to hundreds nanometers. Chemical analyses showed that the stoechiometric composition was observed from 4 to 5 mum from the surface and the chemical composition was homogeneous along the foil surface. A crystalline texture was observed in the (2 0 (2) over bar 5) planes for Bi-rich alloys. Another preferential crystalline orientation is observed in the (1 1 (2) over bar 0)planes for Sb-rich alloys but the texture is then obvious for the highest quenching temperature. This fine grain microstructure associated to the chemical homogeneity makes the ultrarapid quenching process a promising route for thermoelectric materials elaboration. (C) 2001 Elsevier Science B.V. All rights reserved.