Effect of Exposure to Air on the Phase Composition and Particle Size of Nanocrystalline Lead Sulfide

Abstract

Nanocrystalline powders of lead sulfide with particle size from 5 to 105 nm have been synthesized by chemical deposition from aqueous solutions of lead acetate or nitrate using sodium sulfide as sulfidizing agent and in the presence of sodium citrate or Trilon B as complexing agents. The exposure of the nanopowders to air for six years has shown that PbS nanopowders obtained in the presence of sodium citrate Na3Cit, which behaves as both complexing and stabilizing agent, display the largest stability of phase composition. The stabilizing role of Na3Cit is due to its ability to form a shell on nanoparticle surface to prevent lead sulfide oxidation. It has been established that nanoparticle size remains constant and stable upon long-term keeping in air. The phase composition of PbS nanopowders prepared using Trilon B gradually changes owing to oxidation into lead sulfate upon long-term exposure to air.