Lead telluride

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Lead telluride[1][2] [3]
Names
Other names
Lead(II) telluride
Altaite
Identifiers
1314-91-6 YesY
PubChem 4389803
Properties
PbTe
Molar mass 334.80 g/mol
Appearance gray cubic crystals.
Density 8.164 g/cm3
Melting point 924 °C (1,695 °F; 1,197 K)
insoluble
Band gap 0.25 eV (0 K)
0.32 eV (300 K)
Electron mobility 1600 cm2 V−1 s−1 (0 K)
6000 cm2 V−1 s−1 (300 K)
Structure
Halite (cubic), cF8
Fm3m, No. 225
a = 6.46 Angstroms
Octahedral (Pb2+)
Octahedral (Te2−)
Thermochemistry
50.5 J·mol−1·K−1
-70.7 kJ·mol−1
110.0 J·mol−1·K−1
Hazards
Safety data sheet External MSDS
Repr. Cat. 1/3
Harmful (Xn)
Dangerous for the environment (N)
R-phrases R61, R20/22, R33, R62, R50/53
S-phrases S53, S45, S60, S61
Flash point Non-flammable
Related compounds
Other anions
Lead(II) oxide
Lead(II) sulfide
Lead selenide
Other cations
Carbon monotelluride
Silicon monotelluride
Germanium telluride
Tin telluride
Related compounds
Thallium telluride
Bismuth telluride
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N verify (what is YesYN ?)
Infobox references

Lead telluride (Phoebe) is a compound of lead and tellurium (PbTe). It crystallizes in the NaCl crystal structure with Pb atoms occupying the cation and Te forming the anionic lattice. It is a narrow gap semiconductor with a band gap of 0.32 eV.[4] It occurs naturally as the mineral altaite.

Properties[edit]

Applications[edit]

PbTe has proven to be a very important intermediate thermoelectric material. The performance of thermoelectric materials can be evaluated by the figure of merit, ZT=S^2\sigma T/\kappa, in which S is the Seebeck coefficient, \sigma is the electrical conductivity and \kappa is the thermal conductivity. In order to improve the thermoelectric performance of materials, the power factor (S^2\sigma) needs to be maximized and the thermal conductivity needs to be minimized.[5]

The PbTe system can be optimized for power generation applications by improving the power factor via band engineering. It can be doped either n-type or p-type with appropriate dopants. Halogens are often used as n-type doping agents. PbCl2, PbBr2 and PbI2 are commonly used to produce donor centers. Other n-type doping agents such as Bi2Te3, TaTe2, MnTe2, will substitute for Pb and create uncharged vacant Pb-sites. These vacant sites are subsequently filled by atoms from the lead excess and the valence electrons of these vacant atoms will diffuse through crystal. Common p-type doping agents are Na2Te, K2Te and Ag2Te. They substitute for Te and create vacant uncharged Te sites. These sites are filled by Te atoms which are ionized to create additional positive holes.[6] With band gap engineering, the maximum zT of PbTe has been reported to be 0.8 - 1.0 at ~650K.

Collaborations at Northwestern University boosted the zT of PbTe by significantly reducing its thermal conductivity using ‘all-scale hierarchical architecturing'.[7] With this approach, point defects, nanoscale precipitates and mesoscale grain boundaries are introduced as effective scattering centers for phonons with different mean free paths, without affecting charge carrier transport. By applying this method, the record value for zT of PbTe that has been achieved in Na doped PbTe-SrTe system is approximately 2.2.[8]

In addition, PbTe is also often alloyed with tin to make lead tin telluride, which is used as an infrared detector material.

References[edit]

  1. ^ Lide, David R. (1998), Handbook of Chemistry and Physics (87 ed.), Boca Raton, FL: CRC Press, pp. 4–65, ISBN 0-8493-0594-2 
  2. ^ Lide, David R. (1998), Handbook of Chemistry and Physics (87 ed.), Boca Raton, FL: CRC Press, pp. 5–24, ISBN 0-8493-0594-2 
  3. ^ Lawson, William D (1951), "A method of growing single crystals of lead telluride and selenide", Journal of Applied Physics, J . Appl. Phys. 22 (12): 1444–7, doi:10.1063/1.1699890 
  4. ^ Kanatzidis, Mercouri G. (2009-10-07). "Nanostructured Thermoelectrics: The New Paradigm? †". Chemistry of Materials 22 (3): 648–659. doi:10.1021/cm902195j. 
  5. ^ He, Jiaqing; Kanatzidis, Mercouri G.; Dravid, Vinayak P. (2013-05-01). "High performance bulk thermoelectrics via a panoscopic approach". Materials Today 16 (5): 166–176. doi:10.1016/j.mattod.2013.05.004. 
  6. ^ Dughaish, Z. H. (2002-09-01). "Lead telluride as a thermoelectric material for thermoelectric power generation". Physica B: Condensed Matter 322 (1–2): 205–223. doi:10.1016/S0921-4526(02)01187-0. 
  7. ^ Biswas, Kanishka; He, Jiaqing; Zhang, Qichun; Wang, Guoyu; Uher, Ctirad; Dravid, Vinayak P.; Kanatzidis, Mercouri G. (2011-02-01). "Strained endotaxial nanostructures with high thermoelectric figure of merit". Nature Chemistry 3 (2): 160–166. doi:10.1038/nchem.955. ISSN 1755-4330. 
  8. ^ Biswas, Kanishka; He, Jiaqing; Blum, Ivan D.; Wu, Chun-I.; Hogan, Timothy P.; Seidman, David N.; Dravid, Vinayak P.; Kanatzidis, Mercouri G. (2012-09-20). "High-performance bulk thermoelectrics with all-scale hierarchical architectures". Nature 489 (7416): 414–418. doi:10.1038/nature11439. ISSN 0028-0836. 

External links[edit]