Effects of low-melting temperature salt (Na2SO4) addition on the phase transformation, crystal growth, and chroma of titanium dioxide pigments

• Effects of low-melting temperature salt (Na2SO4) onTiO2 properties are studied.
• The relationships between the TiO2 crystalline and morphology with the chroma were analyzed.
• Liquid-phase sintering processes increased the TiO2 particle growth and phase transformation.

The effects of the presence of a low-melting temperature inorganic salt (sodium sulfate) on the phase transformation, particle morphology and chroma of titanium dioxide white pigment were investigated. Powders were characterized by X-ray powder diffraction, scanning electronic microscopy, ultraviolet–visible–near infrared spectroscopy, infrared spectra and chroma measurements. For titanium dioxide pigments containing a lower salt content, the anatase–rutile phase transformation and crystal growth of titanium dioxide were inhibited. On the other hand, the anatase–rutile phase transformation and crystal growth of titanium dioxide was accelerated by the addition of higher salt concentrations. The chroma was observed to change with rutile content and morphology of the prepared samples. Here, the enhancement effects of salt doping on the phase transformation and crystal growth of titanium dioxide are understood via liquid-phase sintering processes.

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