STRUCTURAL AND MAGNETIC ASPECTS OF A MIXED FLUORIDE SERIES - FE1-XGAXF3 (0 LESS-THAN-OR-EQUAL-TO X LESS-THAN-OR-EQUAL-TO 1)

Several solid solutions of the mixed fluoride series Fe(1-x)Ga(x)F3 with 0 less-than-or-equal-to x less-than-or-equal-to 1 were synthesized by solid state reaction. They crystallize in space group R3BARc, identical to that of r-FeF3 and r-GaF3. The presence of six-fold coordinated trivalent high-spin iron atoms is evidence by Mossbauer spectroscopy. The magnetic ordering temperatures decrease linearly with increasing gallium content and vanish at the extrapolated value 1 - x = 0.31, close to the theoretical percolation threshold. High field Mossbauer spectroscopy and susceptibility measurements give a clear evidence for antiferromagnetic interactions.