  Single crystals of Zn_(1-x)Mn_xIn_2Se_4 were grown by the chemical vapour
phase transport technique (CVT). The Mn concentration was varied from x=1 to
x=0.01. Through X-rays powder diffraction patterns and Laue diagrams of single
crystals we studied the transformation from the hexagonal structure of
MnIn_2Se_4 to the tetragonal structure of ZnIn_2Se_4.
