Quasibinary section of AgGaSe<sub>2</sub>-PbS
In recent years, researchers in optoelectronics have been interested in investigating the compound AIBIIICVI2 (AI-Cu, Ag; BIII-Ga, In ; CVI-S, Se) with a chalcopyrite structure and the solid solutions. This attention is mainly due to the promising use of copper and silver-containing representatives of these compounds (CuInS2, CuInSe2) with p-type conductivity as an absorbing layer of thinfilm solar cells. The ligatures (AgGaSe2, PbSe) were synthesized in evacuated quartz ampoules from elements taken in appropriate ratios at 1150 and 1370 Kfor 3 h, followed by air cooling. Pb, Ag, Ga, and Se of high purity with a basic substance content of at least 99.999% were used as starting materials. The samples were annealed at 600 K for 300-350 h. Samples of the AgGaSe2-PbSe section were synthesized at 1150-1370 K. The samples obtained were annealed at 600 K for 350 h. The XRD, DTA, and metallographic analysis, microhardness and density measurements were used to study phase equilibria in the AgGaSe2-PbSe section of the Ag2Se-Ga2Se3-PbSe quasi-ternary system. The T-x phase diagram of the system was constructed, and the presence of a quaternary compound of the composition AgPb2GaSe4, formed at 1110 K by the peritectic reaction, was established. The conditions of formation were determined, and the physicochemical properties of the AgPb2GaSe4 compound were studied. It was found that the AgPb2GaSe4 compound crystallized in the orthorhombic system with the crystal lattice parameters a = 8.5201, b = 7.2311, c = 6.9203 Å, Sp.gr. Pmn21. It was shown that the solubility based on AgGaSе2 at room temperature reached 12 mol.% (β-phase), and on the basis of PbSe, 8 mol.%AgGaSe2.