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

Single-phase cubic Pb1-xAgxS limited solid solutions based on PbS with a metal sublattice doped with Ag are produced. The maximal relative content of Ag in the Pb1-xAgxS solid solutions reaches up to x = 0.15. The thermal expansion of semiconductor Pb1-xAgxS 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 Pb1-xAgxS 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 Pb1-xAgxS solid solutions, the spatial distributions of the modulus of elasticity E, the Poisson ratio mu, and the linear compressibility beta in relation to the (hkl) direction are determined. The reflectance spectra of synthesized PbS, Ag2S, and Pb1-xAgxS 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.