Voids in Packing (IMAGE) Moscow Institute of Physics and Technology Caption Tetrahedral (blue) and octahedral (red) voids in a two-layer packing and their position in the unit cell (bottom). Credit MIPT's press office Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.