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Thermoelectric Performance of Epitaxial Thin Films of Layered Cobalt Oxides Grown by Reactive Solid‐Phase Epitaxy with Topotactic Ion‐Exchange Methods
Author(s) -
Sugiura Kenji,
Ohta Hiromichi,
Koumoto Kunihito
Publication year - 2007
Publication title -
international journal of applied ceramic technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.4
H-Index - 57
eISSN - 1744-7402
pISSN - 1546-542X
DOI - 10.1111/j.1744-7402.2007.02145.x
Subject(s) - epitaxy , materials science , thermoelectric effect , thin film , electrical resistivity and conductivity , cobalt , substrate (aquarium) , analytical chemistry (journal) , phase (matter) , seebeck coefficient , chemical engineering , nanotechnology , metallurgy , composite material , thermal conductivity , chemistry , physics , engineering , organic chemistry , layer (electronics) , chromatography , geology , thermodynamics , oceanography , electrical engineering
This article reviews high‐quality epitaxial film growth of layered cobalt oxides by reactive solid‐phase epitaxy (R‐SPE) with topotactic ion‐exchange methods. Epitaxial film of Na 0.8 CoO 2 was grown on a (0001)‐oriented α‐Al 2 O 3 substrate by R‐SPE using CoO film as the starting material. The Na 0.8 CoO 2 epitaxial films were converted into high‐quality epitaxial films of Sr 0.32 Na 0.21 CoO 2 and [Ca 2 CoO 3 ] x CoO 2 by topotactic ion‐exchange methods. The Sr 0.32 Na 0.21 CoO 2 film exhibited better stability against moisture than that of the Na 0.8 CoO 2 film, while it retained the good thermoelectric properties of Na 0.8 CoO 2 . The [Ca 2 CoO 3 ] x CoO 2 film exhibited a high electrical conductivity of 2.95 × 10 2 S/cm and a large Seebeck coefficient of +125 μV/K at 300 K.