Perpustakaan Digital ITB

Liquid-like binary Cu2??X (X = S, Se, and Te)chalcogenides and their ternary solid solutions have gainednotable attention in thermoelectrics due to their interestingand abnormal thermal and electrical transport properties.However, previous studies mainly focus on a single elementalloying at either an anion or cation site whereas theinvestigation on cation/anion co-alloying is very rare so far.Here, a series of quaternary Cu2?2xAg2xSe1?xSx(x= 0.01, 0.03,0.05, 0.1, 0.15) liquid-like copper chalcogenide materials havebeen fabricated and the effects of Ag/S co-alloying on the thermoelectric properties of Cu2Se have been systematically studied.It is found that all compounds are mixed phases at room temperature but single cubic phase at high temperatures. Theintroduction of Ag and S in Cu2Se brings about a large massfluctuation rather than strainfieldfluctuation that effectivelysuppresses the lattice thermal conductivity. Furthermore, on increasing the Ag and S contents, the high electrical conductivity ofpristine Cu2Se is well tuned to the optimal range derived from the single parabolic band model analysis. Consequently, a peakzTof 1.6 at 900 K is achieved in Cu1.8Ag0.2Se0.9S0.1, which is about 33% higher than that of binary Cu2Se.