CRYSTAL CHEMISTRY AND PHASE DIAGRAMS OF THREE THERMOELECTRIC ALKALINE-EARTH COBALTATE (Ca-M-Co-O, M=Sr, Zn and La) SYSTEMS

摘要

Research interest in waste heat conversion using thermoelectric materials has increased substantially in recent years partly because of the increasing price of fuel and also due to the effect of greenhouse gas emissions. For waste heat energy conversion applications, oxide materials which have high temperature stability are potential candidates. Three phase diagrams of selected systems that contain low dimensional alkaline cobaltates (layers or chains), as well as the crystal chemistry and thermoelectric properties of selected thermoelectric oxides in these systems are summarized. Examples of compounds in these systems that are of interest as potential thermoelectric materials include (Ca,M)_3Co_4O_9 (M=Sr, La), Ca_3(Co, M)_4O_9 (M=Zn), A_(n+2)Co_nCo'O_(3n+3) (A= Sr, Ca), and Ca_(n+2)(Co,Zn)_n(Co,Zn)'O_(3n+3).