Effects of Doping of Lead Sulfide with Silver on the Lattice and Optical Properties of Pb1 –xAgxS Solid Solutions

Resumo

Single-phase cubic Pb_{1 –x}Ag_xS limited solid solutions based on PbS with a metal sublattice doped with Ag are produced. The maximal relative content of Ag in the Pb_{1 –x}Ag_xS solid solutions reaches up to x = 0.15. The thermal expansion of semiconductor Pb_{1 –x}Ag_xS solid solutions is first measured by the dilatometry technique in the temperature range from 295 to 580 K. The replacement of Pb atoms by Ag atoms in Pb_{1 –x}Ag_xS results in a decrease in the coefficient of thermal expansion, which is due to a change in the anharmonicity of atomic vibrations and a slight increase in the elastic properties. For single-crystal PbS particles and Pb_{1 –x}Ag_xS solid solutions, the spatial distributions of the modulus of elasticity E, the Poisson ratio μ, and the linear compressibility β in relation to the (hkl) direction are determined. The reflectance spectra of synthesized PbS, Ag₂S, and Pb_{1 –x}Ag_xS powders are recorded, and it is shown that the replacement of Pb by Ag in PbS is accompanied by an increase in the band gap.