Synthesis and characterization of Mn-doped C@ZrSiO4 black pigment via non-hydrolytic sol-gel method

Abstract

With the increasing popularity of the black decorative ceramics, the development of black pigment with good properties has become significant for the ceramic industry. A Mn-doped zirconium silicate encapsulated carbon (C@ZrSiO4) black pigment was successfully prepared via non-hydrolytic sol-gel (NHSG) method at 800 °C, while MnCl2 and carbon-containing precursors (tetraethoxysilane, TEOS) were used as Mn and in-situ carbon sources, respectively. The results demonstrated that the L* value of black pigment first decreased and increased with the increase of MnCl2 content. The as-prepared pigment with the MnCl2 content of 10 mol% showed a deep dark hue (L* = 27.64, a* = 0.67, b* = 0.68), while the pigment without Mn doping exhibited poor chromatic properties (L* = 51.18). Moreover, XPS and EPR results indicated that the Mn(II) and Mn(IV) replaced the Zr(IV) in ZrSiO4, resulting in the formation of oxygen vacancies. In-situ carbon provided by TEOS incorporated into these oxygen vacancies, which can protect carbon from being oxidized. In addition, the prepared pigment exhibited higher chemical stability in acid/alkali solutions, favorable tinting strength and thermal stability in base transparent glaze, which displayed wide application prospect in the field of ceramic decoration.