Trends in thermodynamic parameters of phase transitions of lanthanide sulfides SrLnCuS3 (Ln = La–Lu)

• Published in: Journal of thermal analysis and calorimetry Vol. 128; no. 2; pp. 993 - 999
• Main Authors: Ruseikina, Anna V., Andreev, Oleg V., Galenko, Eugenia O., Koltsov, Semyon I.
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 2017; Springer Nature B.V
• Subjects: Analytical Chemistry; Chemistry; Chemistry and Materials Science; Enthalpy; Gadolinium; High temperature; Inorganic Chemistry; Lanthanum; Measurement Science and Instrumentation; Melting; Parameters; Phase transitions; Physical Chemistry; Polymer Sciences; Samarium compounds; Temperature; Transition temperature; Lanthanide sulfides; Incongruent melting; DSC; Phase transitions
• ISSN: 1388-6150; 1588-2926
• DOI: 10.1007/s10973-016-6010-9

SrLnCuS 3 (Ln = La–Lu) compounds melt incongruently. Their thermochemical parameters are determined. The melting temperatures and the enthalpies of melting are: for SrLaCuS 3 , T  = 1513 K and Δ H  = 6.9 kJ mol −1 ; for SrCeCuS 3 , T  = 1468 K and Δ H  = 5.2 kJ mol −1 ; for SrPrCuS 3 , T  = 1459 K and Δ H  = 13.2 kJ mol −1 ; for SrNdCuS 3 , T  = 1429 K and Δ H  = 16.8 kJ mol −1 ; and for SrSmCuS 3 , T  = 1605 K and Δ H  = 2.8 kJ mol −1 . Three high-temperature polymorphic transitions are found to occur in SrLnCuS 3 (Ln = Sm, Gd–Lu) compounds. The parameters of these transitions are determined: for SrSmCuS 3 , Tα  ↔  β  = 1452 K, Δ Hα  ↔  β  = 3.0 kJ mol −1 , Tβ  ↔  γ  = 1464 K, Δ Hβ  ↔  γ  = 0.2 kJ mol −1 , Tγ  ↔  δ  = 1476 K, and Δ Hγ  ↔  δ  = 1.1 kJ mol −1 ; for SrDyCuS 3 , Tα  ↔  β  = 1530 К, Tβ  ↔ γ = 1568 К, and Tγ  ↔  δ  = 1585 K; for SrTmCuS 3 , Tα  ↔  β  = 1580 K, Tβ  ↔  γ  = 1618 K, and Tγ  ↔  δ  = 1631 K; and for SrYbCuS 3 , 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 (Ln 3+ ) curves for SrLnCuS 3 (Ln = La–Lu) feature the tetrad effect. The SrLnCuS 3 (Ln = La–Nd) compounds are classified as thiocuprates; their melting temperatures decrease systematically from La to Nd. The SrCuLnS 3 (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.