Thermoelectric Properties Of PBS Based Thermoelectric Materials Prepared By Hydrothermal Synthesis Followed Microwave Sintering Technology

As a medium to convert heat and electricity directly,thermoelectric materials has attracted much attention on the occasion of environmental and energy crisis.So to prepare high conversion efficiency materials through a simple and cheap way become the focus of research.In case of gathering the large number of waste heat from automobile exhaust and industry,problems of resources and environment in our country will be remited to a certain extent.PbTe is a well-developed thermoelectric material in medium temperature at present,however high cost of trace element?Te?limits the commercial applications.Fortunately,PbS has similar crystal and band structure with PbTe,and more,S is rich in crust,so PbS is expected to replace PbTe and will be widely used in the future.But low conductivity and high thermal conductivity lead to low ZT value which limit the application of PbS.Currently,the raw materials used to prepare PbS are concentrated on contain elemental?sufur and plumbum?and preparation method is usually hot pressing or spark plasma sintering,which were either environmental polluted or high equipment cost.To solve these problems,we carried out the following work:?1?Taking thiourea and lead acetate as raw material,cubic PbS with uniform size were quickly and easily prepared through hydrothermal synthesis,combining microwave sintering,bulk PbS with grain size of about 800 nm and relative density about 90% were successfully prepared.Without environmental polluted elemental lead and introduce microwave sintering method for preparing thermoelectric materials are the innovation of this article.?2?Bi³⁺ doping n-type Pb_1-xBi_xS?x=0,0.005,0.01,0.15,0.2,0.25,0.5?were prepared with above method,the results show that no second phases were detected in the system,the electrical conductivity was obviously improved by doping,and the value of Pb_0.995Bi_0.005S was 640 S·cm^-1 at room temperature,compared with undoped samples,the electrical conductivity increased by about 20 times;maximum power factor?PF?of 8.77?W cm^-1 K^-2 was obtained at 800 K and thermal conductivity was 0.7W m^-1 K^-1 eventually,maximum ZT of 0.86 was obtained at 800 K in sample Pb_0.995Bi_0.005S,a fivefold increase of undoped PbS sample.?3?Cl-doping n-type PbS_1-xCl_x?x=0,0.005,0.01,0.15,0.2,0.25,0.5?were prepared,results show that PbS samples doped with Cl-is also single phase and electrical conductivity improved a lot,sample PbS_0.98Cl_0.02 show highest electrical conductivity of 447 S cm^-1 at room temperature,rise 10-fold of PbS sample.The highest PF of 14?w cm^-1 K^-2 were achieved at 673 K in PbS_0.98Cl_0.02,combined with thermal conductivity,a maximum ZT of 1.13 was achieved at 800 K in sample PbS_0.975Cl_0.015.