Solid-state synthesis and characterization of cobalt blue core-shell pigment particles

Mika Yoneda, Kuniaki Gotoh, Makoto Nakanishi, Tatsuo Fujii, Yasuhiro Konishi, Toshiyuki Nomura

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

Cobalt blue is one of the most chemically and thermally stable blue pigments. However, cobalt is scarce and expensive. To minimize the use of cobalt and reduce production costs and toxicity, cobalt blue core-shell pigments were synthesized by a solid-state method, which is cheaper than a liquid-phase reaction. Small cobalt hydroxide particles and large α-alumina particles, in various ratios, were used as the starting materials. The dry mixed powders were calcined at 1200°C for 2 hours. Elemental mappings of the surfaces and cross sections of the synthesized particles showed that the cobalt blue had a core-shell structure. X-ray diffraction patterns showed that the synthesized cobalt blue consisted of an α-alumina core and a cobalt aluminate shell. The color tone of the synthesized cobalt blue was evaluated from the lightness (L*) and chroma (C*) values. The color tone of the cobalt blue synthesized in this study was almost same as those of commercially available samples although the cobalt molar fraction was lower than the stoichiometric ratio (Co/(Co + Al) = 0.33, Co/Al = 0.5) which was calculated from the chemical reaction formula.

Original languageEnglish
Pages (from-to)3468-3476
Number of pages9
JournalJournal of the American Ceramic Society
Volume102
Issue number6
DOIs
Publication statusPublished - Jun 1 2019

Keywords

  • cobalt/cobalt compounds
  • color
  • core-shell structure
  • pigment
  • solid-state reaction

ASJC Scopus subject areas

  • Ceramics and Composites
  • Materials Chemistry

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