Nanomaterials Synthesis and Effect of Granular Disorders on Electrical Behavior of Lanthanum Manganites

Comprehensive investigation on the synthesis and electrical transport behaviors of polycrystalline samples of lanthanum manganite due to static disorder was reported. The process parameters were optimized for different batches to yield variable grain sizes. Different sintering conditions and technique like thermal cycling were employed to obtain better grain packing density. The liquid nitrogen and air quenching of the samples were carried out to restrict the grain growth with well defused grain boundary. Variable grain habits and sizes were synthesized by standard solid-state reaction and modified sol-gel synthesis routes. Large variation of grain size, connectivity and packing was observed by varying sintering temperature and synthesis technique. The process dependent grain sizes were observed in the wide range from 20 nm to 1.5 μm by transmission and scanning electron microscopy. The variations in residual resistivity as well as metal-insulator transitions are observed. The observed data were analyzed on the basis of contributions from various dynamic interactions and static disorders.