Issue 66, 2019

Improvement of near-infrared (NIR) reflectivity and black color tone by doping Zn2+ into the Ca2Mn0.85Ti0.15O4 structure

Abstract

Inorganic black pigments with thermal barrier characteristics, Ca2Mn0.85−xTi0.15ZnxO4−x (0 ≤ x ≤ 0.10), were synthesized using a conventional solid-state reaction method in order to improve the blackness without decreasing the near-infrared (NIR) reflectance of a Ca2Mn0.85Ti0.15O4 pigment, which was previously reported by our group. The composition was optimized to provide both high blackness and NIR reflection characteristics. As a result, the NIR solar reflectance value (RNIR) of Ca2Mn0.77Ti0.15Zn0.08O3.92 (RNIR = 74.6%) became larger than that of Ca2Mn0.85Ti0.15O4 (RNIR = 71.7%), and the black color tone of the former (L* = 23.2, a* = +2.81, b* = +0.83, C = 2.93) was improved in comparison with that of the latter (L* = 24.4, a* = +4.30, b* = +2.72, C = 5.09). This improvement is caused by the introduction of strain into the [MnO6] octahedra and a decrease in the manganese ion concentration. The RNIR value of the Ca2Mn0.77Ti0.15Zn0.08O3.92 pigment was also larger than those of the commercially available pigments (RNIR < 53.0%). Therefore, Ca2Mn0.77Ti0.15Zn0.08O3.92 has potential to be an inorganic black pigment for thermal shielding.

Graphical abstract: Improvement of near-infrared (NIR) reflectivity and black color tone by doping Zn2+ into the Ca2Mn0.85Ti0.15O4 structure

Article information

Article type
Paper
Submitted
27 Sep 2019
Accepted
20 Nov 2019
First published
28 Nov 2019
This article is Open Access
Creative Commons BY license

RSC Adv., 2019,9, 38822-38827

Improvement of near-infrared (NIR) reflectivity and black color tone by doping Zn2+ into the Ca2Mn0.85Ti0.15O4 structure

R. Oka, S. Iwasaki and T. Masui, RSC Adv., 2019, 9, 38822 DOI: 10.1039/C9RA07849E

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

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