Structural and Magnetic Behavior of Oxidized and Reduced Fe Doped LiNbO3 Powders

Changes in structural and magnetic properties have been systematically induced in lithium niobate (LiNbO3) powders, Fe-doped with different concentrations and thermally treated in oxidized and reduced states. A rather strong ferromagnetic response at room temperature with a saturation magnetization of 0.96 Am2kg−1 was obtained for the higher utilized doping concentration, which is of the order of 1% mol. This may be considered a first report of the manifestation of ferromagnetism in nanocrystalline lithium niobate powders within the regime of very low Fe-doping concentrations. Post-thermal treatment in a controlled atmosphere is key for inducing and detecting this behavior, which can also be explained as the effective recombination of Fe impurities with oxygen vacancies in the surface of the material. Mechanochemical-calcination was employed for the synthesis of LiNbO3 powders and after that, a diffusion process of 0.44%, 0.89%, 1.47% and 2.20% mass of Fe2O3 was used in the Fe-doping. Oxidation and reduction processes were performed using a controlled atmosphere of ultra-high purity oxygen and hydrogen, respectively. X-ray diffraction and Raman spectroscopy were employed to characterize the materials. The magnetic properties were studied using Vibration Sample magnetometry and Electron Spin Resonance spectroscopy

Structural and Magnetic Behavior of Oxidized and Reduced Fe Doped LiNbO3 Powders

Changes in structural and magnetic properties have been systematically induced in lithium niobate (LiNbO 3) powders, Fe-doped with different concentrations and thermally treated in oxidized and reduced states. A rather strong ferromagnetic response at room temperature with a saturation magnetization of 0.96 Am 2 kg− 1 was obtained for the higher utilized doping concentration, which is of the order of 1% mol. This may be considered a first report of the manifestation of ferromagnetism in nanocrystalline lithium niobate powders within the regime of very low Fe-doping concentrations. Post-thermal treatment in a controlled atmosphere is key for inducing and detecting this behavior, which can also be explained as the effective recombination of Fe impurities with oxygen vacancies in the surface of the material. Mechanochemical-calcination was employed for the synthesis of LiNbO 3 powders and after that, a diffusion process of 0.44%, 0.89%, 1.47% and 2.20% mass of Fe 2 O 3 was used in the Fe-doping. Oxidation and reduction processes were performed using a controlled atmosphere of ultra-high purity oxygen and hydrogen, respectively. X-ray diffraction and Raman spectroscopy were employed to characterize the materials. The magnetic properties were studied using Vibration Sample magnetometry and Electron Spin Resonance spectroscopy

Structural Aspects LiNbO3 Nanoparticles and Their Ferromagnetic Properties

We present a solid-state synthesis of ferromagnetic lithium niobate nanoparticles (LiNbO3) and their corresponding structural aspects. In order to investigate the effect of heat treatments, two batches of samples with a heat-treated (HT) and non-heat-treated (nHT) reduction at 650 °C in 5% of hydrogen/argon were considered to investigate the multiferroic properties and their corresponding structural aspects; using magnetometry and scanning transmission electron microscopy (STEM). Results indicate the existence of ferromagnetic domains with a magnetic moment per unit cell of 5.24 × 10−3 μB; caused mainly due to voids and defects on the nanoparticle surface, as confirmed by STEM measurements

Hardness and Elastic Modulus on Six-Fold Symmetry Gold Nanoparticles

The chemical synthesis of gold nanoparticles (NP) by using gold (III) chloride trihydrate (HAuCl∙3H2O) and sodium citrate as a reducing agent in aqueous conditions at 100 °C is presented here. Gold nanoparticles areformed by a galvanic replacement mechanism as described by Lee and Messiel. Morphology of gold-NP was analyzed by way of high-resolution transmission electron microscopy; results indicate a six-fold icosahedral symmetry with an average size distribution of 22 nm. In order to understand the mechanical behaviors, like hardness and elastic moduli, gold-NP were subjected to nanoindentation measurements—obtaining a hardness value of 1.72 GPa and elastic modulus of 100 GPa in a 3–5 nm of displacement at the nanoparticle’s surface