Hydrothermally controlled growth and magnetic properties of multi-morphology manganese oxide (RMnO3, R=Ca, Sr, Ba) nano- and microcrystals

This paper presents a general hydrothermal route to multi-morphology manganese oxide (RMnO3, R=Ca, Sr, Ba) nano- and microcrystals and reports the magnetic properties of their nanowires as well. Adjustment of the synthesis conditions, particularly the change of the concentrations of n-hexadecyltrimethylammonium bromide and NaOH, led to the formation of nano- and microcrystals with wire-, belt-, pyramid-, flower-, and arrow-like morphologies. Considering the shape-dependent magnetic properties of nanocrystals, nanowires were selected as representative samples for magnetic measurements. At low temperature, the nanowires exhibited interesting competing ferromagnetic-antiferromagnetic interactions, and the magnetization values increase significantly with increasing the radius of positive ions from Ca2+ to Ba2+.