Light-emitting nanocasts formed from bio-templates: FESEM and cathodoluminescentimaging studies of butterfly scale replicas

Abstract

Nanocasts comprising of red-light-emitting cubicY2O3:Eu phosphors were made from butterfly wing scale bio-templates. We report herein the firstcathodoluminescent images made from such nanocasts and show that valuable insightsinto the nature of the internal structure of the casts can be gained by the useof this technique. The casts faithfully reproduced the fine sub-micrometre sizedetail of the scales, as was made evident by both FESEM and cathodoluminescentimages that were collected from the same sample areas using a hyphenatedFESEM-CL instrument. There was excellent agreement between the FESEM andcathodoluminescent images, the image quality of the latter indicating that theEu3+ activator ions wereevenly dispersed in the Y2O3:Eu phosphor on a sub-micrometre scale. The casts were made by infilling the natural moulds with aY2O3:Eu precursor solution that was subsequently dried and fired to convert it into the phosphormaterial. This method provides a simple, low cost route for fabricating nanostructureshaving feature dimensions as small as 20 nm in size, and it has the potential to be appliedto other metal oxide systems for producing nano-and micro-components for electronic,magnetic or photonic integrated systems.