Growth of an oriented Bi_40−xIn_xTe₆₀ (x = 3, 7) thermoelectric material by seeding zone melting for the enhancement of chemical homogeneity

Abstract

A zone melting technique with seeding has been developed to prepare oriented Bi 40−x In x Te 60 (at%, x = 3; 7) thermoelectric material with enhanced chemical homogeneity. The respective initial compositions of the sample and the seed were chosen according to the pseudo-binary Bi 2 Te 3 -In 2 Te 3 phase diagram that was experimentally redetermined with the aid of a former mushy zone that was resolidified in a temperature gradient. An oriented Bi 40−x In x Te 60 bulk material with a uniform composition close to the target value over the entire length of the zone-melted region along the growth direction has been successfully manufactured.

Anisotropic layered Bi2Te3-In2Te3 composites: control of interface density for tuning of thermoelectric properties

“… The blue lines illustrate the recently reported solidus and liquidus lines 22 , and the red line illustrates the recently reported solvus line of In in Bi 2 Te 3 from ref. 17 .…”

“…Oriented (Bi,In) 2 Te 3 (containing 3, 4, 6, and 7.5 at%In) solid solutions with the {001} plane being parallel to the growth axis were obtained by a seeding zone melting technique 22 . This technique yields an especially uniform composition over the entire length of the zone melted region along the growth direction.…”

“…More details on the control of macroscopic homogeneity via seeding zone melting can be found in ref. 22 . Macroscopic homogeneity is a necessary precondition for the homogeneous distribution of precipitates and thus for a uniform thermoelectric performance of the bulk composite samples.…”

“…1 ). The blue lines illustrate the recently reported solidus and liquidus lines 22 , based on which the concentration of the seed alloy for the seeding zone melting is selected. The seed alloys for 3, 4, 6 and 7.5 at% are 7, 9, 12.5 and 13.5 at%In, respectively.…”

Anisotropic n-Type Bi2Te3–In2Te3 Thermoelectric Material Produced by Seeding Zone Melting and Solid State Transformation

“…In the present work, a seeding zone melting technique was applied to prepare a bulk anisotropic Bi 2– x In x Te 3 solid solution. Excellent chemical homogeneity throughout the whole growing distance was obtained by appropriate selection of seeding crystal . This is particularly important in Bi 2 Te 3 , since the chemical composition plays a crucial role for the thermoelectric properties and the nanostructure formation.…”