Nanocrystals of the quaternary thermoelectric materials: AgPb _mSbTe_m+2 (m = 1-18): Phase-segregated or solid solutions?

A study was conducted to analyze the synthesis of quaternary LAST-m (lead, antimony, silver, telluride) nanocrystals with a wide range of m values and the detailed investigation of their structure on the atomic scale, particularly in terms of Ag and Sb in the nanocrystalline PbTe matrix. The investigation shows that the nanocrystals of LAST-m are homogeneous solid solutions and not further nano-segregated. It also shows that they are metastable at room temperature and phase-separate into PbTe and AgSbTe₂ upon annealing at moderately high temperatures. The solution stability and processability of these semiconducting nanoparticles renders them useful for thin film preparation and device applications. The use of these quaternary nanoparticles are also being investigated for thin film transistors and ordered lithographic patterning to make nanoparticle arrays for sensing, photovoltaics, and thermoelectric applications.