Investigation of the Ho 2Se 3–Cu 2Se–PbSe and Er 2Se 3–Cu 2Se–PbSe systems at 870 K

Abstract

The interactions between the components in the Ho 2Se 3–Cu 2Se–PbSe and Er 2Se 3–Cu 2Se–PbSe systems at 870 K were determined using X-ray single crystal and powder diffraction. The existence of the compounds with compositions RCuSe 2–R 2/3Cu 2Se 2 (Er 2/3Cu 2S 2 structure type, space group P 3 ¯ , a = 0.40563(1) nm, c = 0.64542(3) nm, R I = 0.0737 for HoCuSe 2 and a=0.40407(1) nm, c = 0.64420(3) nm, R I = 0.0660 for ErCuSe 2) and RCu 5Se 4 (unknown structure) was confirmed in the R 2Se 3–Cu 2Se (R = Ho, Er) sections. The existence of the compounds Ho 6Pb 2Se 11 (Y 6Pb 2Se 11 structure type, space group Cmcm, a = 0.40561(2) nm, b = 1.34018(6) nm, c = 3.7525(1) nm) and Er 2PbSe 4 (CaFe 2O 4 structure type, space group Pnma, a = 1.2554(2) nm, b = 0.40778(5) nm, c = 1.4885(2) nm, R I = 0.0914) was confirmed in the R 2Se 3–PbSe (R = Ho, Er) sections. The existence of the compounds Ho 3.33CuPb 1.5Se 7 (Lu 3.33CuPb 1.5Se 7 structure type, space group Cm, a = 1.35314(8) nm, b = 0.40819(2) nm, c = 1.25609(7) nm, β = 104.577(3)°) and HoCuPbSe 3 (β-BaLaCuSe 3 structure type, space group Pnma, a = 1.0516(2) nm, b = 0.40470(8) nm, c = 1.3410(3) nm, R 1 = 0.0541) in the Ho 2Se 3–Cu 2Se–PbSe system was confirmed. The formation of the compounds Er 5CuPb 3Se 11 (Er 5CuPb 3Se 11 structure type, space group Cmcm, a = 0.40688(2) nm, b = 1.34607(7) nm, c = 3.8040(2) nm), Er 3.33CuPb 1.5Se 7 (Lu 3.33CuPb 1.5Se 7 structure type, space group Cm, a = 1.35018(7) nm, b = 0.40693(2) nm, c = 1.25433(6) nm, β = 104.492(2)°) and ErCuPbSe 3 (β-BaLaCuSe 3 structure type, space group Pnma, a = 1.04846(8) nm, b = 0.40424(3) nm, c = 1.34143(7) nm) in the Er 2Se 3–Cu 2Se–PbSe system was confirmed.