Non-Close-Packed Artificial Opals


  • This work was supported by the European Union, project PHOBOS (contract IST1999-19009), the Spanish CICyT ministry (project No. MAT2000-1670-C04), and the Generalitat Valenciana (project No. CTIDIB/2002/68). We acknowledge S. Rubio, who synthesized the colloids, and Drs. J. Sánchez-Dehesa and H. Míguez for their valuable suggestions and stimulating discussion.


Non-close-packed artificial opals consisting of face-centered cubic arrays of spheres interconnected by tubular necks (see Figure and cover) have been obtained. The fabrication method and structural and optical properties are reported. Compared to their close-packed counterparts, non-close-packed opals have: i) much higher porosity and ii) stronger optical scattering, which provokes more intense reflectance peaks caused by larger photonic gaps.