Ba和Ca掺杂对Bi2Sr2Co2Oy热电性能的影响

The Impact of Ba,Ca Doping on Thermoelectric Performance of Bi_2Sr_2Co_2O_y

Bi_2Sr_2Co_2O_y是一种性能优异的层状钴酸盐热电材料,改变材料层与层间错配度可以提高材料的电导率、降低热导率,优化材料的热电性能。本文采用固相反应法合成并制备Bi_2Sr_2Co_2O_y(M=Ca,Ba;x=0,0.05,0.1,0.15,0.2,0.25)样品,通过XRD、SEM等表征样品的物相结构、微观组织。结果表明:Ba和Ca进入晶格,随着Ba和Ca掺杂量的增加,样品的热导率和电阻率与未掺杂的相比明显降低,材料的ZT值显著提升,当掺杂量x=0.2时,Bi_2Sr_2Co_2O_y和Bi_2Sr_2Co_2O_y样品的ZT值最高,在973 K分别达到0.22和0.41,Bi2Sr2Co2Oy热电性能显著改善。

Layered cobalt salts Bi2Sr2Co2Oy display excellent thermoelectric performance. It is reported that changing degree of mismatch between layers can improve the electrical conductivity of materials, reduce the thermal conductivity and optimize the thermoe-lectric performance of materials. The polycrystalline Bi2Sr2-xMxCo2Oy（M=Ca,Ba;x=0, 0.05, 0.1,0.15, 0.2, 0.25） thermoe-lectric bulk samples were prepared based on the classical solid - state reaction method in this paper. The samples ’ crystal phase, structure and morphology were characterized and analyzed by using XRD and SEM. The results showed that when Ba and Ca go into lattice and occupy the Sr site, With the increase of Ba and Ca doping amount, the total thermal conductivity and resistivity are remarkably decreasedand the materials of ZT value significantly increased . When doping amount x = 0. 2,ZT of the Bi2Sr1-8Ba0.2Co2Oy and B i2 Sr1.8Ca0.2Co2Oy sample gets to its maximum and reaches 0. 22 and 0. 41 at 973 K respectively. This results in significant improvement in thermoelectric performance.