Download file (2.11 MB)
Download as zip (1.94 MB)

Collection

Citation

Description:

Spinel-type inorganic pigments with intensive color and chemical/thermal stability are showing extensive applications that could be further broadened by color manipulation and improvement of the material properties through nanosizing. In this study, we report supercritical hydrothermal synthesis of nonstoichiometric spinel-type cobalt gallate nanoparticles (Co–Ga NPs) with controlled color. Without the conventional calcination procedure, NPs with greenish–blue, blue, and yellowish–green colors were synthesized from precursor solutions at pH 7, 9, and 11, respectively, with a low Co/Ga molar ratio of 0.25.
X-ray diffraction, scanning/transmission electron microscopy, and inductively coupled plasma-atomic emission spectroscopy methods suggest that the products were spinel-type cobalt gallate NPs with high crystallinity and a nonstoichiometric composition. Based on an X-ray absorption fine structure investigation, prepared nonstoichiometric Co–Ga NPs were found to have different metal distributions from stoichiometric CoGa2O4 produced by a solid-state reaction during calcination. Particularly, nonstoichiometric Co–Ga NPs with a blue color and a high crystallinity were prepared without calcination for the first time and were found to have lower tetrahedral cobalt occupancy but comparable octahedral cobalt occupancy compared to calcined CoGa2O4. We also discuss strategies that could realize Co–Ga NPs with a more brilliant blue color using the present technique based on an investigation of the growth process.

Rights:

• https://creativecommons.org/licenses/by-nc/3.0/legalcode
  

Keyword: cobalt callate, supercritical hydrothermal synthesis, pigment

Date published: 2023-10-15

Publisher: Royal Society of Chemistry (RSC)

Journal:

• DALTON TRANSACTIONS (ISSN: 14779226) vol. 52 issue. 44 p. 16285-16296

Funding:

Manuscript type: Publisher's version (Version of record)

MDR DOI:

First published URL: https://doi.org/10.1039/d3dt03086e

Related item:

Other identifier(s):

Contact agent:

Updated at: 2024-01-05 22:13:19 +0900

Published on MDR: 2023-12-09 13:30:24 +0900