Ba(OH)2*8H2O in the solid state consists of the [Ba(H2O)8]2+ cations and OH- anions packed into a layered structure, the OH- anions being connected to the hydrogen atoms of the neighbouring [Ba(H2O)8]2+ cations by hydrogen bonds. In case of Ba(OH)2 and Ba(OH)2*H2O the 8-fold coordination of Ba is retained, but OH- ions are directly coordinated to Ba and all oxygen atoms are shared by at least 2 BaO8 polyhedra. Ba(OH)2*H2O is still layered, while in case of Ba(OH)2 a 3D network is formed.

In fact, it is not so easy to describe these structures. If you want to get better understanding, get the structure data from the ICSD database (the crystallography department of your institution should have access) and draw it using any applicable program.

Dear Alexander,

Thanks for your advice.

I think that the information will be very useful for me.

I`ll try to use the applicable program with the structure data from the ICSD.