Neutron thermodiffractometry
of an amorphous AlF3.xH2O :
Negative result from a PDF-2 search by EVA-2 :
TREOR90/ITO/DICVOL91 results
Consistent with a tetragonal cell
although many orthorhombic or even cubic cells were
proposed.
By carefully examining the data, then the space groups P4/nmm or P4/n were obvious.
The cell confirmation was concluded by the Le Bail method :