Microstructure analysis of electrospun La0.8Sr0.2MnO3 nanowires using electron microscopy and electron backscatter diffraction (EBSD)

Anjela Koblischka-Veneva,Jörg Schmauch,Michael R Koblischka,Xianlin Zeng

doi:10.1063/9.0000171

Abstract

The microstructural properties of electrospun La0.8Sr0.2MnO3 (LSMO) nanofibers were investigated using electron microscopy and electron backscatter diffraction (EBSD). By means of EBSD, it is possible to measure the crystallographic orientation of the LSMO grains within an individual nanofiber. As the LSMO grains within the nanofibers are in the 10-nm range, we employ here parts of the recently developed transmission Kikuchi diffraction technique in order to enhance the Kikuchi pattern quality to enable an automated mapping of the crystallographic data. The diffraction results demonstrate that the grain orientation is not random, but there is a texture induced by the shape of the polymer nanofiber formed after the electrospinning step. Within an individual nanofiber section, the dominating grain boundaries are high-angle ones, which play an important role in the current flow through the sample (low- and high field magnetoresistance). The data obtained allow further an analysis of the grain shape aspect ratio, and elucidate the grain and grain boundary arrangement within electrospun LSMO nanofibers.

Highlights

The perovskite compound La1−xSrxMnO3 (LSMO) is known for the high spin-polarized currents, which makes it a material of great interest in spintronics.1–3 The magnetoresistance (MR) observed was found to depend strongly on the microstructure, i.e., the grain boundaries (GBs) and the interfaces between the grains.4–7 LSMO materials are commonly prepared as thin films, or bulk, polycrystalline materials and recently, as nanostructures8,9 which comprise nanopowders, nanocubes and nanowires
Previous investigations have demonstrated that it is possible in this way to increase the MR up to 70 % at low temperature and high fields, whereas the low-field MR is dominated by the wire diameter
There are attempts of strain engineering the magnetic properties of LSMO as thin films on a variety of substrates

Summary

INTRODUCTION

The perovskite compound La1−xSrxMnO3 (LSMO) is known for the high spin-polarized currents, which makes it a material of great interest in spintronics. The magnetoresistance (MR) observed was found to depend strongly on the microstructure, i.e., the grain boundaries (GBs) and the interfaces between the grains. LSMO materials are commonly prepared as thin films, or bulk, polycrystalline materials and recently, as nanostructures which comprise nanopowders, nanocubes and nanowires. LSMO materials are commonly prepared as thin films, or bulk, polycrystalline materials and recently, as nanostructures which comprise nanopowders, nanocubes and nanowires. In such structures, the LSMO grain size is reduced to the 10-nm range and a large interface area results. An analysis of LSMO nanocubes showed that these nanocubes exhibit that oxygen deficiencies and related manganese reduction is confined to just two outer surface perovskite layers.. An analysis of LSMO nanocubes showed that these nanocubes exhibit that oxygen deficiencies and related manganese reduction is confined to just two outer surface perovskite layers.9 This interface may play an essential role to understand the MR properties of LSMO materials. To obtain a strong enough EBSD signal of a nanofiber piece, the newly developed transmission Kikuchi diffraction (TKD) technique was applied here in two ways, i.e., in transmission and reflection mode

EXPERIMENTAL PROCEDURE

Findings

CONCLUSIONS