Grain boundaries in Nanostructured Fluorides
          Nanostructured fluoride powders prepared by high-energy ball milling route were modelled as pseudo cubic and random packing of corner sharing octahedral units corresponding to nanocrystalline grains (~15nm diameter) and disordered grain boundaries (a few nanometres thick), respectively. Their different cationic topologies are consistent with those of AF and SP, respectively. The temperature dependence of the magnetic properties reveals a progressive magnetic decoupling of grains when the temperature increases, originating a superparamagnetic behaviour above a blocking temperature which is dependent on the thickness of the grain boundaries, i.e. the milling conditions. (link) and (link)