TeI_4掺杂量对n型Bi_2Te_3基烧结材料热电性能的影响

Dependence of thermoelectric properties of n-type Bi_2Te_3-based sintered materials on the TeI_4 doping content

采用区熔法结合放电等离子体快速烧结(SPS)技术制备了n型Bi2Te3基热电材料.在300—500K的温度范围内测量了各热电性能参数,包括电导率(σ)、塞贝克系数(α)和热导率(κ),研究了掺杂剂TeI4的含量(质量百分比分别为0,0.05,0.08,0.10,0.13和0.15wt%)对热电性能的影响.结果表明试样的载流子浓度(n)随TeI4含量增加而增大,使电导率增大、塞贝克系数的绝对值先增大而后减小,从而导致品质因子(α2σ)呈先增加后降低的变化趋势;同时,由于异质离子(I-)以及载流子对声子的散射作用增强,可显著降低其晶格热导率.烧结材料的性能优值(ZT=α2σT/κ)对应于TeI4含量为0.08wt%有其最大值,约为0.92.此外,烧结材料的抗弯强度增加至80MPa左右,从而可以显著改善材料的可加工性以及元器件的使用可靠性.

N-type （ Bi2Te3 ）0.93 （ Bi2Se3 ）0.07 thermoelectric materials doped with various content of Tel4 （0, 0.05, 0.08, 0.10, 0.15, and 0.15wt% ） have been fabricated through the combination of zone melting and spark plasma Sintering. Electrical conductivity （σ）, Seebeck coefficient （α） and thermal conductivity （κ） were measured in the temperature range of 300--500K. The influence of the variation of TeI4 content on thermoelectric properties was studied. The increase of TeI4 content caused an increase of carrier concentration and thus resulted in an increase of σ and a decrease of α, and the lattice thermal conductivity was decreased by the increase of phonon scattering resulting from heterogeneous ion （I） scattering and carrier scattering. The maximum figure of merit ZT （ ZT = α^2 σT/κ ） of the sintered materials in the direction perpendicular to the pressing direction showed a value of 0.92 for the sample containing 0.08wt% TeI4 . In addition, the bending strength of the sintered materials was improved to about 80MPa from about 10MPa of the zone-melted ingot, which is of advantage to the fabrication process and the improvement of the reliability for thermoelectric modules.