2023-09-18 タフツ大学
The ancient Roman glass seen up close. “While the age of the glass may be part of its charm, in this case if we could significantly accelerate the process in the laboratory, we might find a way to grow optical materials rather than manufacture them,” said Fiorenzo Omenetto. Photo: Giulia Guidetti
◆フォトニッククリスタルは現代の技術で多くの用途に使用され、光通信デバイスやフィルターなどに応用されています。研究者は、この自然に形成されたフォトニッククリスタルの仕組みを解明し、光学材料の成長に新たなアプローチを提供する可能性を探っています。
◆この研究は、科学と歴史の融合であり、古代のガラスが時間と環境の影響でどのように変化し、美しいフォトニッククリスタルが形成されたのかを調査しています。
＜関連情報＞
- https://now.tufts.edu/2023/09/18/buried-ancient-roman-glass-formed-substance-modern-applications
- https://www.pnas.org/doi/10.1073/pnas.2311583120
古代ローマガラスに刻まれたフォトニック結晶 Photonic crystals built by time in ancient Roman glass
Giulia Guidetti, Roberta Zanini , Giulia Franceschin , Mauro Moglianetti Taehoon,,Kim Nathaniel, Cohan Lisa Chan, John Treadgold, Arianna Traviglia,and Fiorenzo G. Omenetto
Proceedings of the National Academy of Sciences Published:September 18, 2023
DOI:https://doi.org/10.1073/pnas.2311583120
Significance
The study of the hierarchical arrangement of a material and its optical properties provides valuable information about its assembly and building blocks. Here, an archaeological glass fragment from the Roman times was analyzed using a correlated optical-morphological and elemental approach. The analysis revealed a highly reflective metallic patina composed of highly ordered nanostructured domains resembling Bragg-stacks. The study of this patina provides insights into the comodulation of self-assembly and pH-driven nanofabrication processes, involving top–down glass corrosion and bottom–up nano-to-micro-scale structuring of silica nanoparticles into ordered lamellae. This allowed for the observation of phenomena across different temporal windows that are not accessible through existing artificial aging methods.
Abstract
Ancient glass objects typically show distinctive effects of deterioration as a result of environmentally induced physicochemical transformations of their surface over time. Iridescence is one of the distinctive signatures of aging that is most commonly found on excavated glass. In this work, we present an ancient glass fragment that exhibits structural color through surface weathering resulting in iridescent patinas caused by silica reprecipitation in nanoscale lamellae. This archaeological artifact reveals an unusual hierarchically assembled photonic crystal with extremely ordered nanoscale domains, high spectral selectivity, and reflectivity (~90%), that collectively behaves like a gold mirror. Optical characterization paired with nanoscale elemental analysis further underscores the high quality of this structure providing a window into this sophisticated natural photonic crystal assembled by time.
