Local structural orders in nanostructured fluoride powders

Nanostructured fluoride powders were prepared by high-energy ball milling u nder different milling conditions (time and intensity). To investigate the local structural orders, we combined suitable local probe techniques such a s Fe-57 Mossbauer spectrometry (MS) and F-19, Ga-69 and Ga-71 nuclear magne tic 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 th e different hyperfine magnetic and quadrupolar parameters, the correspondin g Mossbauer and nuclear magnetic resonance data were compared to those of c rystalline and amorphous phases and then mutually compared. Two types of lo cal structural orders are unambiguously detected and attributed to the pres ence of crystalline grains and grain boundaries (GB). (C) 2001 Elsevier Sci ence B.V. All rights reserved.