Thermoelectric PbTe-CdTe bulk nanocomposite

TL;DR

This paper presents a novel Bridgman growth method for creating PbTe-CdTe nanocomposites with controlled grain structure and doping, aiming to improve thermoelectric energy conversion efficiency.

Contribution

It introduces a specific synthesis technique leveraging low solubility and temperature control to produce PbTe-CdTe nanocomposites with embedded CdTe grains and tunable doping.

Findings

Successful synthesis of PbTe-CdTe nanocomposites with 100 nm grains.

Ability to produce both n-type and p-type materials with high carrier concentration.

Demonstrated control over grain distribution and doping in the composite.

Abstract

The preparation method of thermoelectric PbTe-CdTe semiconductor nanocomposite in the form of a bulk material doped with Bi, I or Na, intended for production the mid-temperature thermoelectric energy generators is presented. The method takes advantage of the extremely low mutual solubility of both semiconductors, resulting from their different crystal structure, and is based on a specifically designed Bridgman growth procedure. It is shown that the formation of zinc-blende crystalline CdTe grains in the rock-salt matrix of thermoelectric PbTe can be forced during the synthesis of a composite by introducing Cd in the form of CdTe compound and choosing the growth temperature above the melting point of PbTe but below the melting point of CdTe. X-ray diffraction and SEM-EDX spectroscopy analyzes as well as basic electric and thermoelectric characterization of the nanocomposite samples containing 2, 5 and 10 at. \% of Cd showed that using proposed growth procedure, it is possible to obtain both n-type (Bi- or I-doped) and p-type (Na-doped) material with carrier concentration of 1{\div}5 x 10\^{19} cm\^{-3} and uniformly distributed CdTe grains with a diameter of the order of 100 nm.