Melnychuk K. Systems based on the compounds R2S3, MeS, Sn(Si)S2 (R – Ln, Ме – Pb, Fe, Co, Ni): phase equilibria, crystal structure and properties of the sulfide phases

The thesis is devoted to the study of the nature of phase interaction in the R2S3 – MeS – SnS2 systems, the crystal structure of quaternary compounds, the measurement of magnetic characteristics, and the determination of the patterns of the interactions between components. For the first time interactions in quasi-ternary systems R2S3 – МеS – DIVS2 (R – Ln; Ме – Co, Ni; DIV – Si, Sn) were studied; ten isothermal sections of quasi-ternary systems R2S3 – MeS – SnS2 (R – Y, La, Pr, Sm, Tb; Me – Co, Ni) at 770 K were constructed; for the first time, 60 samples were synthesized and the existence of twenty new continuous solid solution series La2-xR'xPbSi2S8, Ce2-xR'xPbSi2S8 and Pr2-xR'xPbSi2S8 (R – Ln) was confirmed; magnetic properties of twenty one chalcogenide phases LaR'PbSi2S8, CeR'PbSi2S8 and PrR'PbSi2S8 (R – Ln) were studied for the first time, their structure contains simultaneously two different rare-earths which form statistical mixtures with Pb atoms; structural perfection of the synthesized solid solutions was analyzed by Raman spectroscopy.