Synthesis and characterization of La_0.825Sr_0.175MnO₃nanowires

Abstract

Perovskite oxide La 0.825 Sr 0.175 MnO 3 (LSMO) nanowires are synthesized using the anodized alumina oxide template technique and the characterization of the microstructure, magnetic and photoluminescence properties is performed. The as-prepared LSMO nanowires 50 nm in diameter and tens of microns in length exhibit polycrystalline perovskite structure. The magnetic measurement reveals the competition between antiferromagnetic ordering and spin glass state as ground state in the nanowires, which is different from the magnetic behaviours of bulk ceramic and single crystals. The photoluminescence (PL) spectroscopy demonstrates strong and broadband emissions with two luminescent peaks at 400 and 420 nm, respectively, which are believed to originate from the selftrapped excitons, oxygen vacancies and surface states, respectively. Nanoscale one-dimensional structures have attracted much interest because of their novel magnetic, electronic and optical properties as a result of their low dimensionality and quantum confinement effect. In addition to the well known examples of carbon nanotubes, ZnO nanobelts and so on, nanowires of complicated perovskite functional oxides such as ferroelectric BaTiO 3 and Pb(Zr, Ti)O 3 , as well as colossal magnetoresistance (CMR) manganites, have been synthesized [1][2][3][4][5]. Among the various methods used for fabrication of nanowires, the template synthesis method has been playing an important role in the fabrication of many kinds of nanowires and nanotubes for their interesting and useful features. Possible templates include nuclear track-etched polycarbonate membranes, nanochannel array glasses,

Influence of Structural Disorder on the Photoluminescence Emission of PZT Powders

“…12 The creation of these localized sates can be provoked by the presence of oxygen vacancies. 22,23 The presence of oxygen vacancies in structurally disordered PZT powders is supported by a coexistence of different types of environments for titanium, evidenced by XANES results, given that the reduction of the TiO 6 cluster to TiO 5 cluster may be accompanied by the creation of electron-captured oxygen vacancies. Oxygen vacancies there are not alone, they are bonded to neighbors.…”

Structural conditions that leads to photoluminescence emission in SrTiO3: An experimental and theoretical approach

“…However, several reports in the literature explain the favorable conditions for PL emission in materials presenting a degree of order-disorder. [28][29][30] The authors attributed the radiative decay process to distorted octahedrons, 28 STEs, oxygen vacancies, surface states, 29 and a charge transfer via intrinsic defects inside an oxygen octahedron. 30 As can been seen, there is no general consensus in the literature about why and how radiative decay takes place in perovskitelike structures with a certain degree of disorder.…”

Large low field magnetoresistance in La0.67Sr0.33MnO3 nanowire devices

“…[1][2][3][4][5] However, a few studies have shown the low field MR ͑LFMR͒ effect through artificial or natural grain boundaries, 6 spin-polarized intergrain tunneling, 7 and in trilayer epitaxial tunnel structures 8 but when the temperature increases to room temperature; the LFMR significantly decreases and makes the materials less attractive for the device applications. Due to the difficulty in LSMO nanowire growth, the electrical and magnetotransport studies on one-dimensional LSMO nanowires are not completely explored [9][10][11] and no work has been reported yet on LFMR at room temperature in LSMO nanowires. 12,13 In this work, we have carried out a systematic investigation on magnetotransport properties of electrospun LSMO wires with diameters ranging from 80 to 300 nm.…”