Dy–Cu–Si system at 1170 K

Abstract

The phase equilibria in the Dy–Cu–Si system were investigated by X-ray powder diffraction and local X-ray spectral analysis; the isothermal cross-section at 1170 K was obtained. The following compounds have been confirmed: DyCu 2Si 2 [CeGa 2Al 2-type, space group I4/ mmm, No. 139, a = 0.3952(1) nm, c = 0.9926(2) nm], DyCu 1–0.5Si 1–1.5 [AlB 2-type, space group P6/ mmm, No. 191, a = 0.4151(1)–0.3975(1) nm, c = 0.3700(1)–0.4012(1) nm], DyCuSi [ZrBeSi (Ni 2In)-type ordered derived structure, space group P6 3/ mmc, No. 194, a = 0.4153(1) nm, c = 0.7404(1) nm], Dy 3Cu 11Si 4 [Sc 3Ni 11Si 4-type, space group P6 3/ mmc, No. 194, a = 0.8411(1) nm, c = 0.8814(1) nm] and Dy 6Cu 8Si 8 [Gd 6Cu 8Ge 8-type, space group Immm, No. 71, a = 1.3665(1) nm, b = 0.6531(1) nm, c = 0.4127(1) nm]. Both phases DyCu 0.5Si 1.5 [ThSi 2-type, space group I4 1/ amd, No. 141-2, a = 0.3985(1) nm, c = 1.3757(3) nm] and Dy 33Cu 63Si 4 [CeCu 2-type, space group Imma, No. 74, a = 0.4292(1) nm, b = 0.6832(1) nm, c = 0.7297(2) nm] are pertaining to an extended homogeneity region, being these based on the solid solutions presented by the DySi 2 (ThSi 2-type) and DyCu 2 (CeCu 2-type) parent binary compounds, respectively. The substitution of Si for Cu stabilizes the high-temperature hexagonal CaCu 5-type modification of the compound DyCu 5; for this reason, the CaCu 5-type phase Dy 17Cu 76Si 7 (space group P6/ mmm, No. 191, a = 0.5004(1) nm, c = 0.4085(1) nm) has been observed in this isothermal section, too.