Electrical transport and magnetic properties of Mn_3O_4-La_(0.7)Ca_(0.3)MnO_3 ceramic composites prepared by a one-step spray-drying technique

摘要

La_(0.7)Ca_(0.3)MnO_3/Mn_3O_4 composites can be synthesized in one step by thermal treatment of a spray-dried precursor, instead of mixing pre-synthesized powders. Another advantage of this composite system is that a long sintering step can be used without leading to significant modification of the manganite composition. The percolation threshold is reached at approx 20 vol percent of manganite phase. The 77 K low field magnetoresistance is enhanced to approx 11 percent at 0.15T when the composition is close to the percolation threshold.