A theoretical model taking into consideration the interface effects is established to predict the Seebeck coefficient and the electrical conductivity for a polycrystalline thermoelectric(TE)thin film.The interface sca...A theoretical model taking into consideration the interface effects is established to predict the Seebeck coefficient and the electrical conductivity for a polycrystalline thermoelectric(TE)thin film.The interface scattering mechanisms(including the film-surface scattering and grain-boundary scattering)of the transport electrons in the film materials are revealed.The relations between the Seebeck coefficient,the electrical conductivity and the interface parameters(the film-surface reflection coefficient and the grain-boundary transmission coefficient)are then discussed with respect to the proposed model.The differences in the TE properties between the films and bulk materials caused by size restriction are investigated.The results indicate that the higher grain number leads to stronger grain-boundary scattering and more distinct size effects of the TE properties.In contrast to the surface effect,the grain-boundary effect plays a main role in the TE properties of TE films with polycrystalline structures.展开更多
采用固相反应法制备了六方纤锌矿结构Zn_(1-x)Al_xO(0≤x≤0.005)系列多晶,探究了Al掺杂对ZnO多晶的微观形貌和热电输运性质的影响。Al掺杂促使ZnO晶粒长大联结,晶界减少,x=0.005时出现在晶界分布的ZnAl_2O_4尖晶石相。各组分样品经二...采用固相反应法制备了六方纤锌矿结构Zn_(1-x)Al_xO(0≤x≤0.005)系列多晶,探究了Al掺杂对ZnO多晶的微观形貌和热电输运性质的影响。Al掺杂促使ZnO晶粒长大联结,晶界减少,x=0.005时出现在晶界分布的ZnAl_2O_4尖晶石相。各组分样品经二次烧结后,电阻率均比对应组分的一次烧结样品增大1~2个数量级。掺杂后样品由ZnO的半导体行为转变为电阻率显著下降的金属行为,一次烧结样品在x=0.004有最小的室温电阻率~10 mΩ·cm,主要由于掺杂使样品载流子浓度和迁移率显著提高;300~950 K下掺杂样品热电势的绝对值和功率因子均随温度升高而增大,x=0.004时有最大的室温功率因子~0.11 m W/m·K^2。综合得到ZnO中Al掺杂的饱和固溶度在0.004~0.005之间。展开更多
基金supported by the National Natural Science Foundation of China(11072093,11121202 and11372120)the PhD Program Foundation of Ministry of Education of China(20110211110023)
文摘A theoretical model taking into consideration the interface effects is established to predict the Seebeck coefficient and the electrical conductivity for a polycrystalline thermoelectric(TE)thin film.The interface scattering mechanisms(including the film-surface scattering and grain-boundary scattering)of the transport electrons in the film materials are revealed.The relations between the Seebeck coefficient,the electrical conductivity and the interface parameters(the film-surface reflection coefficient and the grain-boundary transmission coefficient)are then discussed with respect to the proposed model.The differences in the TE properties between the films and bulk materials caused by size restriction are investigated.The results indicate that the higher grain number leads to stronger grain-boundary scattering and more distinct size effects of the TE properties.In contrast to the surface effect,the grain-boundary effect plays a main role in the TE properties of TE films with polycrystalline structures.
文摘采用固相反应法制备了六方纤锌矿结构Zn_(1-x)Al_xO(0≤x≤0.005)系列多晶,探究了Al掺杂对ZnO多晶的微观形貌和热电输运性质的影响。Al掺杂促使ZnO晶粒长大联结,晶界减少,x=0.005时出现在晶界分布的ZnAl_2O_4尖晶石相。各组分样品经二次烧结后,电阻率均比对应组分的一次烧结样品增大1~2个数量级。掺杂后样品由ZnO的半导体行为转变为电阻率显著下降的金属行为,一次烧结样品在x=0.004有最小的室温电阻率~10 mΩ·cm,主要由于掺杂使样品载流子浓度和迁移率显著提高;300~950 K下掺杂样品热电势的绝对值和功率因子均随温度升高而增大,x=0.004时有最大的室温功率因子~0.11 m W/m·K^2。综合得到ZnO中Al掺杂的饱和固溶度在0.004~0.005之间。
