Study On The Performance Of Magnetic Ion And Light Element Doped BiCuSeO Thermoelectric Materials

BiCuSeO thermoelectric material is a new type of energy material,which can realize the conversion between mechanical and electrical energy without mechanical movement.It has received widespread attention in recent years.However,the BiCuSeO material system has the disadvantages of low electrical conductivity,low Seebeck coefficient,and low carrier mobility,so that the thermoelectric performance of the material is suppressed.This paper hopes to introduce magnetic ions to regulate the Seebeck coefficient on the one hand,and hopes to dope the light element Li to increase the carrier concentration and mobility and thus the conductivity.Therefore,we first studied the effect of light element Li and magnetic ion Mn doped BiCuSeO on its thermoelectric properties;secondly we studied the effect of light element Li and Ca dual doped BiCuSeO on its thermoelectric properties;finally,we studied the doped magnetic ion Ni doped Bi0.94Pb0.06 Cu Se O on its thermoelectric properties.The research results obtained are as follows:1.BiCuSeO samples doped with light element Li and magnetic ion Mn,BiCuSeO samples doped with light element Li and BiCuSeO doped with magnetic ion Mn were prepared by twostep solid phase method.The doping of the light element Li greatly improves the carrier concentration and the carrier mobility,and the electrical conductivity is significantly improved.The spin entropy provided by magnetic ion Mn doping can effectively improve the Seebeck coefficient of the material.Through the coordinated regulation of conductivity and Seebeck coefficient,the power factor of the material is significantly improved.In addition,many nanoprecipitated phases were found in the doped samples.This structure greatly increased the number of phonon scattering,which intensified the phonon scattering and reduced the lattice thermal conductivity.The power factor and lattice thermal conductivity of Li Cu and Mn codoped BiCuSeO were optimized together to make the ZT of this material reach 0.9 at 873 K,which is nearly 3 times higher than the reported performance of the undoped BiCuSeO sample.2.Two-step solid-phase method was used to prepare Li and Ca doped BiCuSeO samples,and the high-temperature thermoelectric properties were studied.Because Li and Ca are doped with high valence Bi,the carrier concentration is sharply increased,and the carrier mobility is also at a high level.Therefore,Li and Ca doped samples effectively improve the conductivity and power factor of BiCuSeO.In addition,the use of mass floating,dual atomic point defects,and nanophases when Li and Ca are substituted for Bi to control the phonon transport process of the material has greatly reduced the thermal conductivity of the material.Finally,the electroacoustic transport performance of the material was optimized through coordinated regulation,so that the thermoelectric figure of merit ZT of the material was significantly increased throughout the temperature range,and reached a maximum of 0.87 at a temperature of 873 K.3.One-step solid-phase method was used to prepare magnetically doped Ni0.94Pb0.06 CuSeO samples.Pb doping introduces additional hole carriers and the delocalization of the 6s orbital isolated electron pair can significantly improve the conductivity of the material.The spin entropy provided by the unpaired 3d electrons of the magnetic ion Ni can effectively improve the Seebeck coefficient of the material.Through the coordinated regulation of conductivity and Seebeck coefficient,the power factor of the material is significantly improved.The presence of nanoparticles and diatomic point defects increases the phonon scattering so that the thermal conductivity of the sample is maintained at a low level,and the thermoelectric figure of merit ZT of the material is increased to 0.91.