arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1701.08286cond-mat.mtrl-sci
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在20-400 K温度范围内具有高热电性能的微米厚氧化物膜

A micrometer-thick oxide film with high thermoelectric performance at temperature ranging from 20-400 K

Jikun Chen, Hongyi Chen, Feng Hao, Xinyou Ke, Nuofu Chen, Takeaki Yajima, Yong Jiang, Xun Shi, Kexiong Zhou, Max Döbeli, Tiansong Zhang, Binghui Ge, Hongliang D… 展开作者

Jikun Chen, Hongyi Chen, Feng Hao, Xinyou Ke, Nuofu Chen, Takeaki Yajima, Yong Jiang, Xun Shi, Kexiong Zhou, Max Döbeli, Tiansong Zhang, Binghui Ge, Hongliang Dong, Huarong Zeng Wenwang Wu, Lidong Chen

摘要:

热电(TE)材料实现热能和电能之间的局部转换,并且转换效率由品质因数zT确定。到目前为止,二维电子气(2DEG)相关的TE材料保持着室温附近zT的记录。对于PbSeTe、Bi_2 Te_3/Sb_2 Te_3和SrNb_(0.2)Ti_(0.8)O_3/SrTiO_3等超晶格材料,当这些TE材料的厚度在空间上被限制在亚纳米尺度内时,观察到zT的急剧增加高达~2.0。载流子的二维限制扩大了费米能级附近的态密度3 -6,并触发了电子-声子耦合。这克服了传统的σ-S权衡以更独立地提高S,从而进一步增加了热电功率因数(PF=S2σ)。然而,由于TE材料的量不足,目前用于高功率能量转换的2DEG材料的实际应用受到空间限制的先决条件的阻碍。在这里,我们报告类似的TE属性2DEG,但实现在SrNb0.2Ti0.8O3薄膜的厚度在亚微米尺度内,通过调节界面和晶格极化。在室温附近及以下,薄膜材料的功率因数高达103 μWcm-1 K-2,zT值高达1.6。在100 μ m厚的SrTiO_3衬底上生长2 μ m厚的SrNb_(0.2)TiO_(0.8)O_3薄膜,即使考虑衬底厚度,薄膜和衬底的积分功率因数也接近102 μWcm ~(-1)K ~(-2)。与传统的2DEG相关TE材料相比,高TE性能对尺寸限制的依赖性降低了~103。生长的氧化膜毒性较小,不依赖于大量的重元素,可能为局部制冷和电功率发电的应用铺平道路。

英文摘要:

Thermoelectric (TE) materials achieve localised conversion between thermal and electric energies, and the conversion efficiency is determined by a figure of merit zT. Up to date, two-dimensional electron gas (2DEG) related TE materials hold the records for zT near room-temperature. A sharp increase in zT up to ~2.0 was observed previously for superlattice materials such as PbSeTe, Bi2Te3/Sb2Te3 and SrNb0.2Ti0.8O3/SrTiO3, when the thicknesses of these TE materials were spatially confine within sub-nanometre scale. The two-dimensional confinement of carriers enlarges the density of states near the Fermi energy3-6 and triggers electron phonon coupling. This overcomes the conventional σ-S trade-off to more independently improve S, and thereby further increases thermoelectric power factors (PF=S2σ). Nevertheless, practical applications of the present 2DEG materials for high power energy conversions are impeded by the prerequisite of spatial confinement, as the amount of TE material is insufficient. Here, we report similar TE properties to 2DEGs but achieved in SrNb0.2Ti0.8O3 films with thickness within sub-micrometer scale by regulating interfacial and lattice polarizations. High power factor (up to 103 μWcm-1K-2) and zT value (up to 1.6) were observed for the film materials near room-temperature and below. Even reckon in the thickness of the substrate, an integrated power factor of both film and substrate approaching to be 102 μWcm-1K-2 was achieved in a 2 μm-thick SrNb0.2Ti0.8O3 film grown on a 100 μm-thick SrTiO3 substrate. The dependence of high TE performances on size-confinement is reduced by ~103 compared to the conventional 2DEG-related TE materials. As-grown oxide films are less toxic and not dependent on large amounts of heavy elements, potentially paving the way towards applications in localised refrigeration and electric power generations.

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