Magnetic and magnetoresistive properties of nanocrystalline Pr <inf>1-x</inf>A<inf>x</inf>Mn<inf>1-y</inf>Co<inf>y</inf>O<inf>3</inf> (A = Sr, Ca; x = 0.3, y = 0.5)

Nanocrystalline Pr1-xAxMn1-yCo yO3 (A = Sr, Ca; x = 0.3, y = 0.5) samples are prepared by sol-gel method. The XRD pattern show single phase and cubic crystal structure with a (=b=c) = 3.862 nm at room temperature. The crystallite size of the samples are calculated using Scherrer formula and found to be ∼15 nm and ∼24 nm for Pr0.7Sr0.3Mn0.5Co 0.5O3 and Pr0.7Ca0.3Mn 0.5Co0.5O3 respectively. The SEM images show the particles are spherical in shape and average particles sizes are about ∼20 nm and ∼25 nm. The samples undergo paramagnetic to ferromagnetic transition about ∼172 K and ∼153 K. The temperature dependence of resistivity (ρ) data show insulating behaviour below 80 K and from 80 K to 300 K, the samples behave like semiconductor. Variable range hopping conduction is found to be dominating for temperatures above 80 K. The maximum magnetoresistance is found to be ∼35 % and ∼24 % at 100 K and it has negative sign. © 2010 American Institute of Physics.