Structural and optical characteristics of pre- and post-annealed sol-gel derived CoCu-oxide coatings

Hussein A. Miran, M. Mahbubur Rahman, Zhong Tao Jiang, Mohmmednoor Altarawneh, Lee Siang Chuah, Hooi Ling Lee, Ehsan Mohammedpur, Amun Amri, Nicholas Mondinos, Bogdan Z. Dlugogorski

Research output: Contribution to journalArticlepeer-review


Sol-gel derived CuCo-oxide coatings as solar selective surfaces, synthesized onto aluminium substrates at various annealing temperatures, are analysed by correlating their structural, chemical bonding states, and surface morphological topographies. As the annealing progressed, all the coatings displayed a Cu 0.56 Co 2.44 O 4 (ICSD 78-2175) phase with preferential orientation along (400) reflection plane. Rietveld refinement of X-ray diffraction (XRD) data indicate that residual stress and microstrains developed around the coating surfaces are reduced resulting in mechanically stable thin films. Enhancement of the crystallite size and preferred orientation of the surface were confirmed via XRD, field emission scanning electron microscopy (FESEM), and atomic force microscopy (AFM) analysis. X-ray photoelectron spectroscopy (XPS) analysis shows tetrahedral, octahedral and mixed states of Cu and Co ions with a stable atomic ratio of Co/Cu, and an increase of O and C contents but no metal-carbon bonding on the surface of materials. Optical reflectance investigations indicated that solar selectivity of the coatings increased from 3.81 to 24 as the annealing temperature reached up to 500 °C.

Original languageEnglish
Pages (from-to)222-235
Number of pages14
JournalJournal of Alloys and Compounds
Issue numberApril
Early online date11 Jan 2017
Publication statusPublished - 15 Apr 2017
Externally publishedYes


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