Insight into the Effect of Counterions on the Chromatic Properties of Cr-Doped Rutile TiO2-Based Pigments.

Xiaojian Zhou,Lanlan Cheng,Chunhai Zou,Huafeng Liu,Botao Han,Xiaozhen Zhang,Renhua Chen

doi:10.3390/ma15062049

Xiaojian Zhou, Lanlan Cheng + Show 5 more

Open Access

https://doi.org/10.3390/ma15062049

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Journal: Materials	Publication Date: Mar 10, 2022
Citations: 2	License type: CC BY 4.0

Affiliation: Jingdezhen Ceramic Institute, Shanghai Customs College

Abstract

Rutile TiO2 pigments codoped with chromophore ion Cr3+ and various charge-balancing ions (i.e., counterions species of Sb, Nb, W and Mo) were prepared by a solid-phase reaction method. The effects of the counterions and calcination temperatures on the phase structure, color-rendering and spectroscopic properties, microstructure, and stability of the synthesized pigments were investigated in detail. The results showed that the introduction of 5–10% counterions improved the solubility of Cr3+ in the TiO2 lattice to form the single-phase rutile pigments calcined at 1100 °C for 2 h. The 10% Cr-doped pigment showed a dark brown color. Depending on the content and type of counterions, the color of the codoped pigments was tailored from yellow to reddish or yellowish-orange to black with different brightness and hue. The influence mechanism of counterions was ascribed to the lattice distortion and variation in the charge balance condition. It was found that the addition of Sb, Nb, or Mo resulted in a remarkable improvement in the NIR reflectance of pigments. The grain growth was inhibited with the codoping of Cr/Sb and Cr/Nb to achieve the nano-sized pigments. In addition, the prepared pigments exhibited good acid and alkali corrosion resistance as well as excellent stability and coloring performance in transparent ceramic glazes.

Highlights

Inorganic pigments are widely used as important colorants for various applications such as coatings, glasses, ceramics, plastics, paints, inks, enamels, and construction materials due to their outstanding thermal stability and high chemical stability as well as excellent coloring ability compared to organic counterparts [1–6]
We systematically investigated the effects of counterion types and doping amounts (5% and 10% in molar ratio) on the phase composition, color-rendering and spectroscopic properties, and morphology of the prepared TiO2-based rutile pigments
When the temperature was increased up to 1000–1200 ◦C, only a single rutile TiO2 phase was obtained without any impurity, which indicates that Cr3+ and Sb5+ cations completely dissolved in the TiO2 lattice [23]

Summary

Introduction

Inorganic pigments are widely used as important colorants for various applications such as coatings, glasses, ceramics, plastics, paints, inks, enamels, and construction materials due to their outstanding thermal stability and high chemical stability as well as excellent coloring ability compared to organic counterparts [1–6]. The Sb-doped rutile pigments are generally considered eco-friendly compared to the above-mentioned toxic pigments with a high content of heavy metal and relatively bad stability. In this work, different counterion species (Sb, Nb, W, or Mo) were codoped with chromophore ion Cr3+ to prepare the rutile TiO2-based pigments by a low-cost solid-state reaction method. We systematically investigated the effects of counterion types and doping amounts (5% and 10% in molar ratio) on the phase composition, color-rendering and spectroscopic properties, and morphology of the prepared TiO2-based rutile pigments. To evaluate the coloring performance and stability of prepared pigments in ceramic glazes, Ti0.9−xCr0.1MxO2 was mixed with a transparent glaze powder in a mass ratio of 5%, and fully dispersed in an appropriate amount of water to obtain a homogeneous glaze slurry.

Characterization Techniques

Results and Discussion

Conclusions