“…Since Pr 3 Se 4 -Pr 2 Se 3 compounds exhibit unique physical and chemical properties (they have high melting (decomposition) temperatures, about 2000 K; Pr 3 Se 4 is a conductor with conductivity σ = 700 Ω -1 ⋅ cm -1 , Pr 2 Se 3 is an insulator with σ = 1 ⋅ 10 -6 Ω -1 ⋅ cm -1 ), they have a great potential as high-temperature thermoelectric materials, catalysts, fluorescent materials, and other functional materials for electrical engineering, nuclear energy, electronic engineering, and laser technology [1][2][3][4][5].…”