Effects of Ag addition on electrical transport and magnetic properties of La0.67Ba0.33Mn0.88Cr0.12O3

We have prepared a series of polycrystalline manganites with the nominal compositions, La0.67Ba0.33Mn0.88Cr0.12O3/Agx (LBMCO/Agx) (x   is the mole fraction) with x=0x=0, 0.05, 0.1, 0.15, 0.2, 0.23, 0.27, 0.3, 0.35. The X-ray diffraction patterns show that the samples with x>0.05x>0.05 are two-phase composites. The Ag addition in LBMCO improves the properties of grain surfaces/boundaries and reduces the resistivity of the composites. For x=0.30x=0.30 sample, a minimum resistivity is obtained and a maximum room temperature magnetoresistance up to −54.5% was observed at 288 K, 1 T field. The room temperature TC and the reduced resistivity are responsible for the enhancement of room temperature MR.