Egyptian blue, Chinese blue, and related two-dimensional silicates: from antiquity to future technologies. Part A: general properties and historical uses

Abstract

The ancient Egyptian blue pigment was developed over 5000 years ago and was used extensively for around four millennia until its use mysteriously declined dramatically during the Early Middle Ages. It recently attracted a lot of attention along with some related materials, leading to a fast-growing number of applications in fields, such as sensors, solar concentrators, energy-saving, and medicine. The new surge in interest began in 1996 with the discovery of their intense NIR photoluminescence that surprisingly can be triggered even by visible light. In 2013, the possibility of exfoliating them and producing NIR luminescent nanosheets was established, expanding the family of 2D nanomaterials. More recently, the discovery of their high antibacterial effects and biocompatibility, and very promising optical, electric and magnetic properties, has further boosted their applications. The characteristics of Egyptian blue are due to its main component: the very stable crystalline compound CaCuSi4O10. This tetragonal sheet silicate is the synthetic analogous of the rare cuprorivaite mineral. In Part A of this review, we summarize the historical uses and main properties (i.e., composition, structure, color, stability, luminescence, and biological activity) of cuprorivaite and related 2D silicates, i.e., BaCuSi4O10 (the main constituent of the ancient pigment Chinese Blue), BaCuSi2O6 (the main constituent of the ancient pigment Chinese Purple), SrCuSi4O10 (synthetic analogous of wesselsite) and BaFeSi4O10 (synthetic analogous of gillespite). The Part B of the review will focus on the modern rediscovery of these materials, their modern synthesis and exfoliation, and the innovative applications based on their properties.

Exploring the Role of Transition Metal Complexes in Artistic Coloration through a Bottom-Up Scientific Approach

“…This pigment was employed in early dynasties on notable historical artifacts and landmarks, such as the famous bust of Queen Nefertiti (Figure 2), and as far as at the ruins of the Parthenon and Pompeii in Rome [2]. Egyptian blue, CaCuSi4O10, makes use of copper as a metallic center, much like other early synthetic pigments such as Chinese Han blue, BaCuSi4O10, and Han purple, BaCuSi2O6, which were both theorized to be developed independently from Egyptian blue [24,25]. Multiple transition metals have been studied for their role in creating the blue and green glazes of ancient Chinese pottery, most notably cobalt, manganese, copper, iron, and titanium [26][27][28].…”

Exploring the Role and Variability of 3d Transition Metal Complexes in Artistic Coloration through a Bottom-Up Scientific Approach

“…This pigment was employed in early dynasties on notable historical artifacts and landmarks, such as in tombs from the Old Kingdom and the famous bust of Queen Nefertiti of the New Kingdom (Figure 2), and as far as at the ruins of the Parthenon and Pompeii in Rome [2]. Egyptian Blue, Ca-CuSi4O10, makes use of copper as a metallic center, much like other early synthetic pigments, such as Chinese Han Blue (BaCuSi4O10) and Han Purple (BaCuSi2O6), which were both theorized to have been developed independently from Egyptian Blue [24,25].…”

“…This pigment was employed in early dynasties on notable historical artifacts and landmarks, such as in tombs from the Old Kingdom and the famous bust of Queen Nefertiti of the New Kingdom (Figure 2), and as far as at the ruins of the Parthenon and Pompeii in Rome [2]. Egyptian Blue, CaCuSi 4 O 10 , makes use of copper as a metallic center, much like other early synthetic pigments, such as Chinese Han Blue (BaCuSi 4 O 10 ) and Han Purple (BaCuSi 2 O 6 ), which were both theorized to have been developed independently from Egyptian Blue [24,25]. The unique quality of transition metals that gives them the ability to produce these bright, visible wavelengths of light derives from their unfilled valence d-orbitals and ligand interactions, resulting in d-d orbital splitting and/or charge transfer [3,13,19].…”

Structure Dynamics and Vibronic Coupling in AECuSi4O10 (AE: Ca, Sr, Ba) Compounds

“…CaCuSi 4 O 10 and BaCuSi 4 O 10 are among the most ancient artificial pigments known as Egyptian Blue and Han Blue, respectively. − The preparation of Egyptian Blue traced back in the predynastic Egyptian period (∼3200 BC) and its diffusion spread over all the Egyptian era, Ancient Greece, and the Roman Empire. The presence of this pigment can be found, for example, in the Nefertiti bust, in the Parthenon, and in Pompei.…”