2006/06/11 by Minhyea Lee, Liliana Viciu, Lu Li +11 · 6 citations
Materials Science · Physics and Astronomy · #Advanced Thermoelectric Materials and Devices #Magnetic and transport properties of perovskites and related materials #Thermal Expansion and Ionic Conductivity #cond-mat.mtrl-sci #cond-mat.str-el
paper · pdf · doi:10.1038/nmat1669
published as Nature Materials 5, 537 (2006). · 6 pages, 7 figures
crossref issued 2006/06/11 · crossref published 2006/06/11 · crossref published-online 2006/06/11 · openalex publication_date 2006/06/11 · crossref created 2006/06/11 · arxiv created 2006/06/15 · crossref published-print 2006/07/01 · arxiv updated 2015/06/25 · crossref deposited 2022/07/06 · openalex created_date 2025/10/10 · crossref indexed 2026/06/08 · openalex updated_date 2026/07/28
Research on the oxide perovskites has uncovered electronic properties that are strikingly enhanced compared with those in conventional metals. Examples are the high critical temperatures of the cuprate superconductors and the colossal magnetoresistance in the manganites. The conducting layered cobaltate \rm NaxCoO2 displays several interesting electronic phases as x is varied including water-induced superconductivity and an insulating state that is destroyed by field. Initial measurements showed that, in the as-grown composition, \rm NaxCoO2 displays moderately large thermopower S and conductivity σ. However, the prospects for thermoelectric cooling applications faded when the figure of merit Z was found to be small at this composition (0.6<x<0.7). Here we report that, in the poorly-explored high-doping region x>0.75, S undergoes an even steeper enhancement. At the critical doping xp∼ 0.85, Z (at 80 K) reaches values ∼40 times larger than in the as-grown crystals. We discuss prospects for low-temperature thermoelectric applications.