Influence of particle size on the magnetic and electrical properties of the system La1-xSrxCoO3-delta (0 < x <= 0.50).

This work focuses on the influence of particle size on the magnetic and ele ctrical properties of the system La1-xSrxCoO3-delta (0 < x less than or equ al to 0.50). For this study we have prepared polycrystalline samples using the ceramic method (particle size: 1 mm < d(1) < 5 mm) and using other alte rnative soft-chemistry techniques that yield materials with smaller particl e size: coprecipitation and nitrate decomposition methods (0.7 mu m <d(2) < 0.9 mu m) and combustion method (0.2 mu m < d(3) < 0.3 mu m). The comparative study of their magnetic and electrical properties shows dif ferences between the series of samples: as the particle size decreases the compositional range for ferromagnetic superparamagnetic and spin-glass beha viors changes, and the materials become magnetically harder; also the elect rical percolation threshold is achieved at higher x, the reentrant semicond ucting behavior, is observed over larger compositional interval and there a re changes in the conduction regime in the semiconducting samples.