Related Experiment Video
Updated: Mar 24, 2026
Synthesis of Non-uniformly Pr-doped SrTiO3 Ceramics and Their Thermoelectric Properties
Published on: August 15, 2015
Synthesis and structural properties of thermoelectric Ca3-xAgxCo4O9+δ powders
Kyeongsoon Park1, Deshmukh Abdul Hakeem1, Jae Sung Cha1
1Faculty of Nanotechnology and Advanced Material Engineering, Sejong University, Seoul 143-747, Korea. kspark@sejong.ac.kr.
Abstract:
A series of Ca3-xAgxCo4O9+δ (0 ≤ x ≤ 0.2) powders is prepared by the Pechini sol-gel method. The effect of dispersants on the size and morphology of the Ca2.9Ag0.1Co4O9+δ powders is investigated. The desired powders are obtained after calcinations of the dried powders at 800 °C for 12 h. The structural and morphological properties are studied with the help of XRD patterns, FE-SEM images, FT-IR spectra, Raman spectra, and XPS spectra. It is found that a mixed valence (+3 and +4) of Co exists in a CdI2-type CoO2 layer, while a mixed valence (+2, +3, and +4) exists in the CoO of a rock salt-type Ca2CoO3 layer. The mixed-valence state in the CoO2 layer can improve the high-temperature thermoelectric properties of Ca3Co4O9 systems.
More Related Videos
Related Concept Videos
01:16Thermal Sigmatropic Reactions: Overview
Sigmatropic shifts are classified based on an order term [i, j ], where i and j indicate the number of atoms across which each end of the σ bond migrates. Below are examples of a [3,3] sigmatropic shift in 1,5-hexadiene, referred...
03:02Colors and Magnetism
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human...