Phase Transition Engineering of Cu2S to Widen the Temperature Window of Improved Thermoelectric Performance. (23rd July 2019)

• Record Type: Journal Article
• Authors: Liang, Xin; Jin, Dou; Dai, Feihu
• Is Part Of: Advanced Electronic Materials. Volume 5:Number 10(2019)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2019-07-23
• Subjects: copper sulfides -- phase transition -- Seebeck coefficient -- thermal conductivity -- thermoelectrics; Materials -- Electric properties -- Periodicals; Materials science -- Periodicals; Magnetic materials -- Periodicals; Electronic apparatus and appliances -- Periodicals; 537
• DOI: 10.1002/aelm.201900486
• Languages: English
• ISSNs: 2199-160X

Abstract

Abstract: Cu2 S compounds are promising thermoelectric (TE) candidate materials with environmentally friendly and earth abundant chemical constituents. A series of phase transitions occur with temperature whereas only the high temperature stabilized cubic structure (α‐Cu2 S) exhibits desirable TE properties. In this work, by alloying Cu sites with Mn, Zn, Ga, and Ge, profound influence on β‐ to α‐Cu2 S phase transition and thermoelectric transport properties is observed. Both phase transition temperature ( T c ) and the enthalpy of phase change (Δ H ) decreases with doping; remarkably, for Cu1.95 Mn0.03 S, T c reduces by ≈156 K. The Seebeck anomaly near the critical point of phase transition also vanishes. The electrical conductivity is remarkably improved for doped samples due to the largely elevated hole concentration. In comparison with pristine Cu2 S, not only is the peak TE power factor substantially enhanced (by ≈272%), but also the average ZT for 500–823 K is highly improved (by ≈145%) due to the successful stabilization of α‐Cu2 S at lower temperatures. The present work offers a clue to enlarge the temperature regime of high TE properties, which is practically useful for a variety of polymorphous thermoelectric compounds. Abstract : The β‐ to α‐Cu2 S phase transition is successfully engineered by alloying Cu sites. Both the peak thermoelectric power factor and the average ZT (for 500–823 K) is substantially improved (by ≈272% for PF and ≈145% for average ZT ). The present work suggests an approach to optimize the thermoelectric performance of transformable polymorphs for a larger temperature window.