“…[18], it was shown that in the FeIn 2 S 4 eMnIn 2 S 4 system, a continuous series of alloys was formed and the structure of the Mn x Fe 1Àx In 2 S 4 alloys was established. Recently, studies of the optical [19] and magnetic properties [20] of the Mn x Fe 1Àx In 2 S 4 alloys as well as In(Al)/(FeIn 2 S 4 ) x (MnIn 2 S 4 ) 1Àx photosensitive structures [21] were reported, activation energies of direct and indirect band-to-band transitions and their variation with composition for the crystals studied was determined.…”