Interface Regulation And Thermoelectric Properties Of Skutterudites

The skutterudites is a kind of medium temperature thermoelectric material with good comprehensive performance.Due to its large carrier mobility and Seebeck coefficient,it has high ZT potential.The higher lattice thermal conductivity which leads to lower ZT.This paper mainly through the high-energy ball mill nanocrystallization,the introduction of graphene,liquid phase compaction to build small angle grain boundary of interface control methods to reduce the lattice thermal conductivity,thereby enhancing the thermoelectric properties.The influence of different interface control methods on the microstructure and thermoelectric properties of skutterudites was studied by XRD,SEM,TEM,laser conductivity,conductivity/Seebeck coefficient test system.The following results were obtained:For the annealed La0.8Ti0.1Ga0.1Fe3CoSb12 skutterudites,the nanostructured bulk material was prepared by high energy ball milling combined with spark plasma sintering(SPS).It was found that the electrical conductivity of the high energy ball milling sample was basically the same as that of the reference sample The power factor of the high-energy ball milling sample reaches a maximum of 28 ?Wcm-1K-2,which is 16%higher than that of the reference sample.The nanostructure of the high energy ball mill enhances the phonon scattering and reduces the lattice thermal conductivity.At 623K,the lattice thermal conductivity reaches the minimum of 0.8 Wm-1K-1,which is 33%lower than that of the reference sample.The nanocrystallization of the structure by high energy ball milling not only improves the electrical properties,but also effectively reduces the lattice thermal conductivity and ultimately improves the thermoelectric properties.The excellent thermoelectric merit of the high energy ball milling sample is increased from 0.8 to 1.05 at 723K.PECVD was used to prepare graphene in situ on p-type La0.8Ti0.1Ga0.1Fe3CoSb12 skutterudites powder annealed.The p-type skutterudites/graphene composites were prepared.It was found that the introduction of graphene has no obvious effect on conductivity of La0.8Ti0.1Ga0.1Fe3CoSb12 skutterudites.But the Seebeck coefficient is slightly improved,and the maximum value of PF is 26 ?Wcm-1K-2 at 723K.The introduction of graphene significantly reduced the lattice thermal conductivity of p-type La0.8Ti0.1Ga0.1Fe3CoSb12 skutterudites,with a minimum value of 0.9 Wm-1K-1 at 673K,which was 25%lower than that of reference sample.The introduction of graphene has little effect on the electrical properties,while the lattice thermal conductivity is significantly reduced,and the ZT value is increased from 0.8 to 1.00 at 723K.The n-type CexCo4Sbi2(x = 0.1,0.125,0.15,0.175,0.2)skutterudites was prepared by melt spinning combined with liquid phase compaction method.It was found that the conductivity increased with the increase of the filling amount,in contrast to conductivity,the Seebeck coefficient decreased with the increase of the filling amount.PF increases first and then decreases with the increase of the filling amount.The sample with the filling amount of x=0.15 has the highest PF,which is about 45.7 ?Wcm-1K-2.The thermal conductivity and the lattice thermal conductivity decrease first and then increase with the increase of the filling amount,and the minimum thermal conductivity is about 3.08 Wm-1K-1.decreases first and then increases with the increase of the filling amount.Ce0.15Co4Sb12 samples reached a maximum ZT of 1.15 at 773K.