Near-Infrared Emission and Photon Energy Upconversion of Two-Dimensional Copper Silicates

Abstract

BaCuSi 4 O 10 (Han blue), CaCuSi 4 O 10 (Egyptian blue), and SrCuSi 4 O 10 are pigments found in many ancient artifacts all over the world. Behind their brilliant color, we demonstrate here that these ancient pigments are strong candidates for photonic materials due to their bright Stokes and anti-Stokes emissions. These pigments give near-infrared emissions (NIR) from Cu 2+ centered at around 930 nm under excitation of 440-800 nm light. This NIR emission can also be produced by pumping using a NIR laser diode. With the rise of pumping density, the emission bandwidth increases notably and stretches to the visible region, giving rise to bright, and broadband photon upconversion (UC). This photon UC process is interpreted in terms of laser-driven blackbody radiation from the ancient pigments.

Ultrathin 2D Inorganic Ancient Pigment Decorated 3D‐Printing Scaffold Enables Photonic Hyperthermia of Osteosarcoma in NIR‐II Biowindow and Concurrently Augments Bone Regeneration

“…The EB (CaCuSi 4 O 10 ) pigment was synthesized by a solid‐state reaction. [ 38 ] Notably, EB has a special stacked lamellar structure which suggests the potentials of exfoliation to obtain the ultrathin NSs ( Figure 2 a ). Scanning electron microscopy (SEM) photographs and the related elemental analysis further verified the platelet‐like peculiarity with distinct layer structure and the homogeneous distribution of Ca, Cu, Si, and O in bulk EB (Figure 2b ).…”

Hydrothermal Formation of Calcium Copper Tetrasilicate

“…During the past five millennia, it has been used extensively as a blue pigment (Egyptian blue), and recent research has focused on its remarkable near infrared luminescence properties 3. In addition to archaeological imaging,4 these investigations have included using Yb 3+ doping to increase near infrared emission,5 evaluating CaCuSi 4 O 10 as the active material in optical sensors,6 measuring the effects of temperature on photoluminescence,7 detailing the electronic structure of the blue chromophore,8 and utilizing the upconversion capability of CaCuSi 4 O 10 under laser excitation to produce bright broadband light 9…”

“…[9] Traditionally CaCuSi 4 O 10 has been prepared by salt-flux routes; [10] the necessary reactiont emperature (ca. 875 8C) was accessible even in antiquity using wood-fired ovens.…”

Phase evolution, crystal structure, and microwave dielectric properties of gillespite‐type ceramics

“…The exfoliation of A CuSi 4 O 10 provides a new route to a new class of 2D nanomaterials. The broad excitation and near‐infrared emission make A CuSi 4 O 10 ideal candidates for infrared light‐emitting devices, security ink formulations, and radiometric sensors based on absorption‐based indicators 20,21 . Moreover, phase transition and negative thermal expansion coefficient are observed for single‐crystalline BaCuSi 4 O 10 22 .…”