Thermoelectric Properties Of Bicuseo With Doping And Composite

In order to solve environmental pollution problems and energy problems that are more and more serious,thermoelectric materials that realize direct heat electricity conversion have attracted large numbers of researchers.Layered oxide thermoelectric BiCuSeO has great potential for studied and application due to its low thermal conductivity,non-poisonous,non-pollution and chemical stability at high temperature.In this paper,cheap K2CO3 as raw material,we manufacture K doped BiCuSeO samples successfully by an ultra-fast ceramic preparation process that is self-propagating high-temperature synthesis(SHS)combined with spark plasma sintering(SPS).The hole concentration of doped sample has increased,so the conductivity has improved.At the same time,doping introduces a large amount of impurities and point defects in the sample,which reduces the thermal conductivity of the sample.Finally,a maximum ZT value of doped samples reaches 0.6,which is 50%higher than the pure sample.Bi1-XSnXCuSeO samples have been prepared using SHS and SPS by Sn powders.There are Sn2+ and Sn4+ in the sample,and the Sn2+ ions could increase the conductivity.However,the SnO and SnO2 secondary phases existing in the system all have high thermal conductivity and increase the thermal conductivity of doped samples.Eventually,the Bi0.96Sn0.04CuSeO sample has the largest ZT value of 0.77,which is 88%higher than the pure phase sample.The Pb-doped BiCuSeO system has high electrical property and high thermal conductivity.Therefore,we used a simple ball milling method to composite Te powders or Te nanowires in Pb-doped BiCuSeO system,respectively.After composited Te powders,the carriers of the sample are scattered,so the electrical properties are reduced.At the same time,the phonons are effectively scattered to obtain a lower thermal conductivity.A sample with a composite volume percentage of 5%achieved a maximum ZT value of 0.77.The samples composited Te nanowires have a better Seebeck coefficient due to the presence of one-dimensional nanowires which cause energy filtering effect,and thus show better electrical properties.Finally,a sample with a composite volume percentage of 5%achieved a maximum ZT value of 1,which was a 45%increase compared to the uncomposited sample and a 144%increase compared to the pure phase sample.