Trends in thermodynamic parameters of phase transitions of lanthanide sulfides SrLnCuS3 (Ln = La–Lu)
作者:Anna V. Ruseikina、Oleg V. Andreev、Eugenia O. Galenko、Semyon I. Koltsov
DOI:10.1007/s10973-016-6010-9
日期:2017.5
SrLnCuS3 (Ln = La–Lu) compounds melt incongruently. Their thermochemical parameters are determined. The melting temperatures and the enthalpies of melting are: for SrLaCuS3, T = 1513 K and ΔH = 6.9 kJ mol−1; for SrCeCuS3, T = 1468 K and ΔH = 5.2 kJ mol−1; for SrPrCuS3, T = 1459 K and ΔH = 13.2 kJ mol−1; for SrNdCuS3, T = 1429 K and ΔH = 16.8 kJ mol−1; and for SrSmCuS3, T = 1605 K and ΔH = 2.8 kJ mol−1. Three high-temperature polymorphic transitions are found to occur in SrLnCuS3 (Ln = Sm, Gd–Lu) compounds. The parameters of these transitions are determined: for SrSmCuS3, Tα ↔ β = 1452 K, ΔHα ↔ β = 3.0 kJ mol−1, Tβ ↔ γ = 1464 K, ΔHβ ↔ γ = 0.2 kJ mol−1, Tγ ↔ δ = 1476 K, and ΔHγ ↔ δ = 1.1 kJ mol−1; for SrDyCuS3, Tα ↔ β = 1530 К, Tβ ↔ γ = 1568 К, and Tγ ↔ δ = 1585 K; for SrTmCuS3, Tα ↔ β = 1580 K, Tβ ↔ γ = 1618 K, and Tγ ↔ δ = 1631 K; and for SrYbCuS3, Tα ↔ β = 1567 K, Tβ ↔ γ = 1608 K, and Tγ ↔ δ = 1621 K. The transitions are observed both upon heating and upon cooling. The high-temperature phases are not quenchable. Phase-transition temperature versus r(Ln3+) curves for SrLnCuS3 (Ln = La–Lu) feature the tetrad effect. The SrLnCuS3 (Ln = La–Nd) compounds are classified as thiocuprates; their melting temperatures decrease systematically from La to Nd. The SrCuLnS3 (Ln = Sm, Gd–Lu) compounds are classified as thiolanthanates; their melting temperatures increase in the order from Sm to Tm and from Tm to Lu.
SrLnCuS3 (Ln = La–Lu) 化合物不一致熔化。测定它们的热化学参数。熔化温度和熔化热函为: 对于 SrLaCuS3,T = 1513 K 且 ΔH = 6.9 kJ mol−1;对于 SrCeCuS3,T = 1468 K 且 ΔH = 5.2 kJ mol−1;对于 SrPrCuS3,T = 1459 K 且 ΔH = 13.2 kJ mol−1;对于 SrNdCuS3,T = 1429 K 且 ΔH = 16.8 kJ mol−1;对于 SrSmCuS3,T = 1605 K 且 ΔH = 2.8 kJ mol−1。在 SrLnCuS3 (Ln = Sm、Gd–Lu) 化合物中发现了三种高温多晶型转变。确定这些转变的参数:对于 SrSmCuS3,Tα ↔ β = 1452 K,ΔHα ↔ β = 3.0 kJ mol−1,Tβ ↔ γ = 1464 K,ΔHβ ↔ γ = 0.2 kJ mol−1,Tγ ↔ δ = 1476 K,且 ΔHγ↔δ=1.1kJmol−1;对于 SrDyCuS3,Tα ↔ β = 1530 К,Tβ ↔ γ = 1568 К,Tγ ↔ δ = 1585 K;对于 SrTmCuS3,Tα↔β=1580K,Tβ↔γ=1618K,Tγ↔δ=1631K;对于 SrYbCuS3,Tα ↔ β = 1567 K,Tβ ↔ γ = 1608 K,Tγ ↔ δ = 1621 K。在加热和冷却时都可以观察到转变。高温相不可淬火。 SrLnCuS3 (Ln = La–Lu) 的相变温度与 r(Ln3+) 曲线具有四分体效应。 SrLnCuS3 (Ln = La-Nd) 化合物被归类为硫代铜酸盐;它们的熔化温度从 La 到 Nd 系统地降低。 SrCuLnS3 (Ln = Sm, Gd–Lu) 化合物被归类为硫代镧酸盐;它们的熔化温度按从Sm到Tm、从Tm到Lu的顺序增加。