Sol-gel synthesis and crystal chemical properties of the pigment Zn1.9Cu0.1SiO4

Abstract

The pigment Zn_1.9Cu_0.1SiO₄ was obtained by the method of sol-gel synthesis. The crystallization temperature was set at 776 °C, ∆H ≈ -16.3 kJ/mol. Thermal expansion of the individual Zn₂SiO₄ and Zn_1.9Cu_0.1SiO₄ solid solutions was studied by in situ high-temperature X-ray diffraction. It is shown that the substitution of Zn²⁺ → Cu²⁺ does not lead to significant changes in the lattice parameters; in the range from room temperature to 800 °C the structure expands monotonically when heated. The coefficients of volumetric thermal expansion for Zn₂SiO₄ and Zn_1.9Cu_0.1SiO₄ are α_V = 8.05 · 10^-6 and 8.81 · 10^-6 1/K, respectively. The colorimetric coordinates in the RGB system are 71.8% red, 72.9% green and 79.6% blue, which corresponds to the gray-blue pigment.