Preparation and magnetic properties of the double-perovskite A[sub 2]FeMoO[sub 6] (A=Ca, Sr, Ba) polycrystals with nanometer-scale particles.

Polycrystalline double perovskites A[sub 2]FeMoO[sub 6] (A=Ca, Sr, Ba) with nanometer-scale grain size have been synthesized using a sol-gel method. The grain size of the samples is controlled within nanometer scale by sintering at different temperatures. The phase purity and the crystal structure of the samples are analyzed by x-ray powder diffraction measurements. The electrotransport and magnetic properties are also measured in this article. In comparison with the large grain samples with micrometer scale, the nanometer-scale grain samples have different magnetic properties, such as lower magnetic transition temperatures and larger magnetoresistance, which can be explained in terms of size effect. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]