Nanosized Sodium-Doped Lanthanum Manganites: Role of the Synthetic Route on their Physical Properties

TL;DR

This study compares two synthesis methods for nanosized sodium-doped lanthanum manganites, revealing how the synthetic route influences their grain size, magnetic behavior, and magnetoresistive properties, with potential applications in magnetic devices.

Contribution

It demonstrates that the synthetic route significantly affects the physical properties of sodium-doped lanthanum manganites, providing insights for tailored material synthesis.

Findings

Polyacrylamide-based sol-gel yields smaller grains (~35 nm)

Propellant synthesis results in larger grains (~55 nm) with broader distribution

Both samples exhibit superparamagnetic behavior and enhanced low-field magnetoresistance

Abstract

In this paper we present the results of the synthesis and characterisation of nanocrystalline La1-xNaxMnO3+delta samples. Two synthetic routes were employed: polyacrylamide-based sol-gel and propellant synthesis. Pure, single phase materials were obtained with grain size around 35 nm for the sol-gel samples and around 55 nm for the propellant ones, which moreover present a more broaden grain size distribution. For both series a superparamagnetic behaviour was evidenced by means of magnetisation and EPR measurements with peculiar features ascribable to the different grain sizes and morphology. Preliminary magnetoresistivity measurements show enhanced low-field (< 1 T) magnetoresistance values which suggest an interesting applicative use of these manganites.