Effect of Europium Substitution on Thermoelectric Properties of Noble-Metal Silicon Clathrates with Ba_8&minus;<i>_x</i>Eu<i>_x</i>Cu<i>_y</i>Si_46&minus;<i>_y</i> Nominal Compositions

Abstract

The effect of the substitution of a rare-earth element for a guest element on the electronic and thermoelectric properties is investigated for clathrates with the nominal composition Ba 8¹x Eu x Cu y Si 46¹y (x = 0, 1, 2; y = 4, 5, 6). The Seebeck coefficient and the electrical conductivity of the rare-earth-substituted Ba 8¹x Eu x Cu y Si 46¹y samples are consistent with n-type conduction and metal-like behavior. The Hall carrier mobility of Ba 8¹x Eu x Cu 6 Si 40 at room temperature decreases with increasing Eu substitution. The conduction band effective mass of rare-earth-substituted Ba 8¹x Eu x Cu 6 Si 40 (x = 1, 2) is experimentally estimated to be larger than that of Ba 8 Cu 6 Si 40 . On the basis of ab initio electronic structure calculations for Ba 6 Eu 2 Cu 6 Si 40 and Ba 8 Cu 6 Si 40 , it is deduced that the conduction band edges of Ba 8 Cu 6 Si 40 are modified by the substitution of Eu for the guest atom Ba, resulting in an increase in the density-of-states effective mass, which is consistent with the experimental result.

Effect of HPHT Processing on Structural and Thermoelectric Properties of Low-Cost Type-I Clathrate Ba8Cu6Si40

“…So it is necessary to cut down the consumption of Ge. More importantly, Si-based clathrates have the advantages of price and weight. , As we all know, Ba 8 Si 46 can only be synthesized at high pressure (over 3 GPa), and it is impossible to form it under atmospheric pressure. , Although some Si-based clathrate samples doped other elements have been synthesized at atmospheric pressure, they are often accompanied by impurity phase. , In a manner of speaking, Si-based clathrates are more suitable for high-pressure synthesis. So, we attempt to investigate the synthesis, microstructures, and TE properties of low-cost clathrate Ba 8 Cu 6 Si 40 by HPHT method.…”