Photonic crystals built by time in ancient Roman glass

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.

Non-destructive 3D exploration of silicate glass corrosion: a combined multiscale approach from the macro to the nanoscale

“…In a previous study, 20 the sample was identified as a fragment of a Roman glass object using laser ablation – inductively coupled plasma – mass spectroscopy (LA-ICP-MS). This analysis revealed that the unaltered core of the glass had a silica-soda-lime high-magnesium (HMG) composition.…”

How a Piece of Roman Glass Became a Photonic Crystal

“…Now, after subjecting the shard to a string of Photograph of the glass shard from Aquileia. Credit: CCHT-IIT, courtesy of National Archeological Museum of Aquileia/Italian Ministry of Culture chemical and physical tests, Giulia Guidetti of Tufts University, Massachusetts, and her collaborators have identified the origin of the shard's appearance: a chemical transformation of the amorphous glass into a nanolayered material, a photonic crystal [1].…”