Basing on dilatometric and optical anisotropy studies, we have obtained (x, T)-phase diagram for TlIn(S_1–xSe_x)₂ solid solutions in the range 0 ≤ × ≤0.25 of selenium concentrations. It has been found that increasing selenium concentration leads to decrease in almost all of phase transition (PT) temperatures. At the same time, the temperature T_i of PT into incommensurate phase for the polytype c = c ₀ increases at the selenium concentrations higher than 0.1, and we observe a tendency to broadening of the temperature region where the incommensurate phase exists. The incommensurate–ferroelectric PT reveals a notably diffuse character. We have also demonstrated that the TlIn(S_1–xSe_x)₂ solid solutions have a polytype structure. It manifests itself in availability of additional PT in the solid solutions with 0 ≤ × ≤0.05. Most probably, the latter corresponds to ferroelectric transformation in the polytype with c = 16c ₀.

基于膨胀和光学各向异性研究，我们获得了硒浓度在0≤× ≤0.25范围内的TlIn（S _1–x Se _x）₂固溶体的（x，T）相图。已经发现，硒浓度的增加导致几乎所有相变（PT）温度的降低。同时，对于多型c  =  c ₀，PT的温度T _i 进入不相称的相 当硒浓度高于0.1时，碳原子的含量增加，我们观察到存在不相称相的温度区域变宽的趋势。不相称的铁电PT表现出明显的扩散特性。我们还证明了TlIn（S _1–x Se _x）₂固溶体具有多型结构。其表现为在固溶体中0≤×≤0.05的其他PT的可用性。后者很可能对应于c  = 16 c ₀的多型铁电转变。