Synthetic Conditions and Color Characteristics of Tantalum Nitride Prepared by Liquid NH3 Process

概要

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Tantalum nitrides and oxynitrides, such as Ta3N5 and TaON, respectively, have exhibited promising properties as red and yellow pigments that do not contain toxic heavy metals. We have developed a process for preparing nitrides or oxynitrides that involves the vacuum-calcination of a precursor material obtained by reaction between a metal halide and liquid NH3. Herein, we describe the synthetic conditions of the liquid NH3 process that affects the color, and thus the color characteristics of resulting pigments. Reaction and post-reaction treatment conditions were adjusted to attain the desired red color ; specifically, a powder with a color index of L*=a*=33.11 and b*=30.53 was obtained by the liquid NH3 process using 0.5 eq of NH2OH-HCl (relative to TaCl5) as the oxygen source, and calcination of the precursor at 973 K under vacuum, followed by recalcination at 673 K for 60 min under air.
Japan Society of Colour Materialの論文