Preparation And Thermoelectric Properties Of Layered Oxides In₂O₃ (ZnO)₃ And BiCuSeO

Thermoelectric(TE)materials can directly realize the conversion between electrical energy and thermal energy,and have wide application prospects in the field of waste heat recovery,accurate temperature control and self-driven sensors.Therefore,the large-scale application of TE materials is conducive to improving energy utilization and alleviating the energy crisis.In this work,two kinds of oxide thermoelectric materials,In₂O₃(Zn O)₃ and BiCuSeO,have been studied.Aimed at the problems of high thermal conductivity of In₂O₃(Zn O)₃ and low electrical conductivity of BiCuSeO,the preparation methods and doping methods were used to improve the thermoelectric properties of the two oxide materials.Besides,Ga₂O₃ doped In₂O₃(Zn O)₃ bulk samples were prepared by solid-phase method,and the microstructure,electrical and thermal transmission properties were studied.It has shown that Ga₂O₃ doping can effectively inhibit grain growth,and the second phase is precipitated from the In₂O₃(Zn O)₃ matrix when Ga₂O₃ is doped to a certain concentration.At 973 K,the minimum thermal conductivity of In₂O₃(Zn O)₃ is1.45 Wm^-1K^-1 when Ga₂O₃ is 0.5 mol%.And the highest ZT value is 0.21,which is an increase of 28.57%compared to the undoped sample.In order to improve the thermoelectric properties of In₂O₃(Zn O)₃,Cu Ni-In₂O₃(Zn O)₃ bulk samples were prepared by electroless plating and spark plasma sintering.The research shows that compared with uncoated In₂O₃(Zn O)₃sample at 873 K,the electrical conductivity of Cu Ni-In₂O₃(Zn O)₃is significantly improved,from 17.18 Scm^-1 to 2074.97 Scm^-1,and the ZT value is increased from0.06 to 0.10.Finally,Bi_1-xBa_xCu Se O bulk samples were prepared by solid-phase method and SPS method.Ba O was selected as the doping element,and the influence of doping concentration on the thermoelectric properties was investigated.After Ba O doping,the forbidden band width is gradually reduced as the increasing of conductivity.And when the doping amount of Ba O is greater than x=0.175,the solid solution limit is reached,and Ba Se O₃ is formed by unsolidified Ba O and Se from the matrix.Above all,compared with undoped BiCuSeO,the ZT of Bi_0.825Ba_0.175Cu Se O increased from0.4 to 0.82 at 873 K.