“…α-Ge 3 N 4 has the following lattice parameters: a = 8.202 Å and c = 5.941 Å [26] with a density of 5.254 g/cm 3 . There is also a rhombic structure attributed to Ge 3 N 4 with the following lattice parameters: a = 13.84 Å, b = 9.06 Å, and c = 8.18 Å [34]. β-Ge 3 N 4 has a density of 5.287 g/cm 3 [21] and refractive index of 2.1 [23,24].…”