Study On Preparation Of ZnO Thermoelectrical Materials

Thermoelectric material is a new energy material that can realize the direct conversion of thermal energy to electric energy by utilizing the movement of internal carriers.It has the advantages of simple structure and good stability,and has become a hot spot in the research field of new energy materials.ZnO-based thermoelectric materials have the advantages of high Seebeck coefficient,stable performance,economical price,and great application prospects in thermoelectric materials.The introduction of pores can effectively reduce the thermal conductivity of materials.Additionally,the composite materials are also an effective means to improve thermoelectric properties.In this paper,M_xZn_1-xO?M is Al,Fe,Ni,x=0.01,0.02,0.03,0.04?nano-ceramic powders were prepared by hydrothermal method,and the pored ZnO-based thermoelectric material were prepared by acetic acid as binder and traditional solid phase sintering method;The composite thermoelectric material of CNTs/Al_xZn_1-xO were prepared by combining ceramic powder with CNTs and SPS sintering.The lattice structure and micromorphology of the powder were characterized and analyzed.It was found that the ceramic powder prepared by hydrothermal method had high purity,good crystallinity and uniform size?average particle size is 100 nm?,among which Al_xZn_1-xO powder appeared an agglomeration phenomenon;Fe_xZn_1-xO and Ni_xZn_1-xO showed a lattice distortion with increasing doping amount.The effects of acetic acid and doping concentration on the morphology,lattice structure and thermoelectric properties of ceramics were investigated.It was found that the introduction of acetic acid caused different sizes of pores in the grains;The density of Ni_xZn_1-xO increased with increasing the doping concentration.The density of Ni_0.01Zn_0.99O is 654.9?W/K²m at773K.At T=447K,the PF of Al_0.02Zn_0.98O reached 887.2?W/K²m.Fe_xZn_1-xO was converted from a N-type semiconductor to a P-type semiconductor,and the PF of Fe_0.04Zn_0.96O at 773K was 679.2?W/K²m;In the characterization of the lattice structure,micromorphology and thermoelectric properties of composite ceramics,the existence of CNTs could not be found.With increasing the doping concentration,the lattice structure of the sample was destroyed,which greatly reduced the thermoelectrical performance of ceramics,among which CNTs/Al_0.01Zn_0.99O had a power factor PF of 432.8?W/K²m at 773K.