热变形工艺制备强织构n型碲化铋基热电材料及其性能研究

Study on Preparation of Strong-textured n-type Bismuth Telluride Based Thermoelectric Material by Hot Deformation and its Properties

采用高纯原料并按名义成分Bi_(2)Te_(2.7)Se_(0.3)配料,利用工业化设备及区熔工艺得到晶体取向性良好的材料,然后通过热变形工艺获得了较强织构的n型碲化铋基合金。该合金保持了区熔晶棒的高功率因子,同时热变形诱导产生的多尺度微观结构能散射宽波长的声子,有效降低了材料的热导率,使其热电优值(ZT)明显提升。进一步掺杂SbI_(3)对材料进行优化,最终制备的n型热变形样品在300 K下具有最大ZT值1.11,而在300~460 K温度范围内平均ZT值达到1.02,同时抗弯强度较区熔样品提升了3倍多。热变形工艺优化了碲化铋基热电材料的电输运和热输运性能,使其在中低温余热发电领域展现出广阔的应用前景。

High-purity raw materials were employed and mixed according to the nominal composition of Bi_(2)Te_(2.7)Se_(0.3),and then the materials with good crystal orientation were obtained by industrial equipment and zone melting process.Subsequently, the n-type bismuth telluride based alloy with strong texture was obtained by hot deformation process.The above alloy maintains the high power factor of zone-melted crystal rod, and its multi-scale microstructure induced by hot deformation can scatter phonons with wide wavelengths, which effectively reduces the thermal conductivity of the material and significantly increases its thermoelectric figure of merit(ZT).The material was further optimized by doping SbI_(3).The finally prepared n-type hot-deformed sample has a maximum ZT value of 1.11 at 300 K and an average ZT value of 1.02 in the temperature range of 300~460 K,while its compressive strength is more than three times higher than that of the zone-melted sample.The thermal deformation process optimizes the electrical transport and heat transport performance of bismuth telluride based thermoelectric material, which shows a broad application prospect in the field of power generation from medium and low temperature waste heat.