PbTe

PbTe, or lead telluride, is a binary IV–VI semiconductor known for its narrow electronic band gap and infrared response. It crystallizes in the rock-salt (NaCl-type) structure with cubic symmetry and a lattice constant of about 6.46 Å. Its electronic structure features a direct band gap of roughly 0.32 eV at the L point of the Brillouin zone, enabling strong infrared absorption.

The material is highly dopable, and its electrical properties can be tuned by intrinsic defects and aliovalent substitutions. This tunability, combined with its narrow band gap, yields favorable thermoelectric and infrared-optical performance. PbTe can be p-type or n-type depending on synthesis conditions and dopants, with carrier concentration control essential for optimizing device operation.

Thermoelectric properties are a defining feature of PbTe. It exhibits a high thermoelectric figure of merit (ZT) at elevated temperatures, especially when alloyed or nanostructured to reduce lattice thermal conductivity while maintaining good electrical transport. Common strategies include forming Pb1−xSnxTe and PbTe1−ySey alloys, and doping with elements such as Na, Tl, or Ag to tailor the carrier concentration and the Seebeck coefficient.

Applications of PbTe span infrared detection and thermoelectric energy conversion. Its mid-infrared band gap makes it useful for detectors, while its thermoelectric performance supports waste heat recovery and solid-state cooling in specialized modules.

Synthesis typically involves direct reaction of lead and tellurium or appropriate precursors, followed by crystal growth using methods such as Bridgman or Czochralski techniques. Because lead and tellurium compounds are toxic, proper handling and disposal are essential.