PbNb2O6 has a space group is Bb2₁m. The unit cell has a = 35.2920 , b = 17.9430 , and c = 7.746. One of the Nb is at positions (0.0716, 0.1792, 0.25), and one of the O is at (0.0736, 0.2064, 0). (a) What is the Nb O bond length between these atoms? (b) Define each of the symbols in the space group. (c) What is the corresponding point group? (d) Give the coordinates of one Nb atom that is related to the one given by the 21 screw axis that intersects the unit cell at (, 0, ). (e) Draw the stereographic projection for the point group.

- 1. PbNb206 has a space group is Bb2 m. The unit cell has a = 35.2920 , b = 17.9430 , and c=7.746. One of the Nb is at positions (0.0716,0.1792, 0.25), and one of the O is at (0.0736,0.2064,0). (a) What is the Nb - O bond length between these atoms? (b) Define each of the symbols in the space group. (c) What is the corresponding point group? (d) Give the coordinates of one Nb atom that is related to the one given by the 2 screw axis that intersects the unit cell at (44,0, 44). (e) Draw the stereographic projection for the point group