New X-ray powder diffraction data on δ-Al2O3

X-ray powder diffraction data, high resolution electron microscopy observation and refined unit cell parameters for δ-Al2O3 prepared from γ-Al2O3 are reported here. The new lattice parameters were a=7.9631(7) and c=23.3975(23) Å with space group P41212 (No. 92). The new data provide evidence for the simple tripling of the unit cell of the starting γ-Al2O3 spinel.