Applied Physics Express · 2008 · 40 citations · 9 references
EngineeringThermoelectricsChemistryThermal ConductivitySemiconductorsNominal Composition Sr8alxga16-xsi30Transport PropertiesSuperconductivityN-type Degenerated SemiconductorsThermodynamicsType-viii StructuresMaterials ScienceMaterials EngineeringElectrical EngineeringThermoelectric PropertiesPowder MetallurgySemiconductor MaterialHigh Temperature MaterialsElectronic MaterialsApplied PhysicsThermoelectric MaterialFunctional MaterialsThermal PropertyThermal Properties
Nominal composition Sr8AlxGa16-xSi30 (0≤x≤16) samples were prepared by powder metallurgy. The samples with x=0–7 exhibited the type-I clathrate structure (Pm3n, No. 223), while the samples with x=8–13 almost exhibited the type-VIII clathrate structure (I43m, No. 217). These samples possessed the electrical conductivities and Seebeck coefficients typical of n-type degenerated semiconductors. The results on their thermoelectric properties indicate that the type-VIII SrAlGaSi clathrate would be a more efficient thermoelectric material than the type-I SrAlGaSi clathrate. For example, the type-VIII Sr8Al9Ga7Si30 sample had a maximum power factor of 11 µW cm-1 K-2 at 1000 K and a room temperature Hall mobility of 24 cm2 V-1 s-1, while those of the type-I Sr8Al6Ga10Si30 sample were 7 µW cm-1 K-2 and 5 cm2 V-1 s-1, respectively.
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