Local structural orders in nanostructured fluoride powders

Nanostructured fluoride powders were prepared by high-energy ball milling under different milling conditions (time and intensity). To investigate the local structural orders, we combined suitable local probe techniques such as 57Fe Mِssbauer spectrometry (MS) and 19F, 69Ga and 71Ga nuclear magnetic resonance (NMR) applied to FeF3 and GaF3 milled samples, respectively. Both isomer shifts and chemical shifts are consistent with the presence of only corner-sharing octahedral units in these systems. After analysis of the different hyperfine magnetic and quadrupolar parameters, the corresponding Mِssbauer and nuclear magnetic resonance data were compared to those of crystalline and amorphous phases and then mutually compared. Two types of local structural orders are unambiguously detected and attributed to the presence of crystalline grains and grain boundaries (GB).