Low temperature structure of magnesium nitrate hexahydrate, Mg (NO3)2·6H2O: A neutron diffraction study at 173 K

From compounds in the system Mg(NO3)2-H2O, crystalline hexahydrate, Mg(NO3)2·6H2O, was chosen as a model substance in order to study melting processes. Mg(NO3)2·6H2O shows a two-stage melting process by having an additional phase transition. We present structural results for Mg(NO3)2·H2O of low temperature α-phase at 173 K using neutron single crystal diffraction. The neutron diffraction measurements confirmed the monoclinic space group P21/c yielding lattice constants a = 6.190(2)Å, b = 12.614(4)Å, c = 6.56(1)Å, and β = 93.72(1) ° at 173 K.