High-throughput Experimental Screening For Bulk Telluride Thermoelectric Materials

With the launched“Materials Genome Initiative”?MGI?projects,the idea of combined high-throughput?HTP?computational and experimental techniques are swiftly introduced to thermoelectric area and effectively accelerating the development of thermoelectric materials.HTP experiments aim to obtain the relationship among composition-phase-performance with fewer experiments and screen out optimal material systems with optimized compositions.Generally,the HTP sample fabrication technique could be divided into two categories,i.e.,material gene chip?MGC?technology and continuously gradient composition preparation?CGCP?technique.The MGC technology could prepare a series of sample libraries with independent components.However,it intends to miss certain mutating performance,while CGCP technique can prepare all compositions in a continuous gradient sample.In addition,MGC technology is focus on thin films and it's hard to utilize the relevant physical parameters of films to develop traditional thermoelectric materials.Meanwhile,the thermoelectric applications are mainly based on bulk modules.It's quite urgent to develop HTP experimental techniques of bulk samples.With the purpose of continuously gradient composition,we have realized the full-chain bulk experiments of HTP,including the preparation of cylinder-like samples with composition gradients,the HTP sample annealing processes and characterizations of composition and thermoelectric properties.With the decreasing the errors and preparation of gradient cylinder-like samples,the home-made automatic batching and prepressing system is designed.On the basis of phase diagrams and thermodynamic theories,the controlled diffusion areas are optimized by spark plasma sintering and annealing process.Finally,the quasi-continuous gradient composition samples were prepared.The crystal structures and composition distributions of the HTP samples were characterized and analyzed by microarea X-ray diffractometry and SEM-EDS.To efficiently screen out satisfactory compositions of thermoelectric performance,Seebeck coefficient scanning mappings are performed on continuous component samples by constructing electric transportation.The in-situ infrared thermal characterization device is set up to quickly visualize the distribution of thermal transport properties using infrared thermal imaging.Up to now,we have synthesized bulk HTP samples with graded compositions through spark plasma sintering and subsequent annealing procedure in Bi_2-xSb_xTe₃?x=1?2?and Bi₂Te_3-xSe_x?x=0?1.5?systems.By combining the HTP characterization techniques,the best Sb/Bi and Te/Se ratios are determined.1.Developed automatic batching and prepressing system.The device can distribution of the sample elements is above 0.93.2.The crystal structure and composition distribution of the HTP samples quasi-continuous composition distribution.3.Performing the electrical transport characterization on quasi-continuous maximum Seebeck coefficient is 155?V/K corresponding to Bi Sb Te₃;In the Bi₂Se_3-xTe_x system,the maximum Seebeck coefficient is-260?V/K corresponding to Bi₂Te_2.1Se_0.9.With the Seebeck coefficient mapping,it can quickly screen the optimal components of continuous component samples.4.Quickly characterizing thermal transport of samples.The home-made apparatus equipped with an in situ dynamic vacuum rapid-heating unit and an infrared camera was developed and applied to characterize thermal properties of a sample with multiple composition areas.In Bi_2-xSb_xTe₃?x=1?2?system,the composition of Bi Sb Te₃ has the lowest thermal conductivity.5.The PSM can be used to study the Seebeck coefficient change in small solid solution by preparing diffusion couples.It is notable that annealing temperature needs to balance diffusion and element volatilization in multiple diffusion couples.