Exfoliation of Egyptian Blue and Han Blue, Two Alkali Earth Copper Silicate-based Pigments

The preparation and exfoliation of CaCuSi₄O₁₀ and BaCuSi₄O₁₀ are described. Upon stirring in hot water, CaCuSi₄O₁₀ spontaneously exfoliates into monolayers, whereas BaCuSi₄O₁₀ requires ultrasonication in organic solvents. Near infrared (NIR) imaging illustrates the NIR emission properties of these materials, and aqueous dispersions of these nanomaterials are useful for solution processing.