Li-and Mn-rich layered oxides show significant promise as electrode materials for future Li-ion batteries. However, an accurate description of its crystallography remains elusive, with both single-phase solid solution and multiphase structures being p r o p o s e d f o r h i g h pe r f o r m i n g m a t e r i a l s s u c h a s Li 1.2 Mn 0.54 Ni 0.13 Co 0.13 O 2 . Herein, we report the synthesis of singleand multiphase variants of this material through sol−gel and solidstate methods, respectively, and demonstrate that its crystallography is a direct consequence of the synthetic route and not necessarily an inherent property of the composition, as previously argued. This was accomplished via complementary techniques that probe the bulk and local structure followed by in situ methods to map the synthetic progression. As the electrochemical performance and anionic redox behavior are often rationalized on the basis of the presumed crystal structure, clarifying the structural ambiguities is an important step toward harnessing its potential as an electrode material.
Accurate characterization of the nanocrystal shape with high statistical relevance is essential for exploiting the strongly shape-dependent properties of cuboidal nanoparticles toward applications. This work presents the development of a new small-angle scattering form factor based on the superball geometry. The superball quantifies the characteristic rounding of corners and edges of cuboidal nanoparticles with a single parameter. Applied to small-angle scattering data of sufficiently monodisperse nanoparticles, the superball form factor enables differentiation between the effects of extended particle size distribution and irregular particle shape. The quantitative application of the superball form factor is validated against microscopy data for a series of monodisperse nanoparticles and implemented into the user-friendly, open-source software Sasview.
Stacking nanoscale-building blocks into onedimensional (1D) assemblies with collective physical properties is a frontier in designing materials. However, the formation of 1D arrays using weak magnetic fields and an in-depth understanding of their magnetic properties remain challenging. Here, low-dimensional assemblies of iron oxide nanocubes with a disordered arrangement are fabricated at the diethylene-glycol/air interface in the presence of assembly fields (0/1/3/5/30/50 mT). Ring-shaped assemblies gradually transform as the assembly field increases from 0 to 50 mT, first to a porous network consisting of elongated assemblies and then to an aligned array of filaments, in which the aligned filaments are formed when the assembly field is ≥3 mT and duration t > 14 min. Spin-glass characteristics and static (dynamic) anisotropy factors~2(3) are achieved by tuning the strength of the assembly field. In the presence of a relatively weak assembly field, the interplay between dipolar interactions and disorder with respect to magnetic easy axis alignment leads to spin-glass characteristics. The alignment of the magnetic easy axes and the strength of the dipolar interactions increase with increasing assembly field, resulting in the disappearance of spin-glass characteristics and enhancement of the magnetic anisotropy. This study presents a strategy for obtaining magnetic assemblies with spin-glass behavior and controllable anisotropy while shedding light on the magnetic interactions of low-dimensional assemblies.
Since addition of Al in Li 0.5 La 0.5 TiO 3 has enhanced ionic conductivity in bulk materials, it is important to apply this material on all solid state thin film batteries. Because some of the good ionic conductors such as Lithium Phosphorus Oxynitride (LiPON) are sensitive to oxygen and moisture and their application is limited, so amorphous Li 0.5 La 0.5 Ti 1−x Al x O 3 (LLTAlO) is a most promising candidate because of its stability. In this study, the crystalline LLTAlO targets were prepared changing the amount of x content by conventional solid state reactions. Using these targets, lithium lanthanum titanium oxide (LLTO) thin film electrolytes were deposited on ITO/SLG substrates by radio frequency magnetron sputtering system in Ar atmosphere. The structural and compositional properties of targets and thin films were characterized by SEM, XRD, Raman spectroscopy and XPS. It was found that all targets are crystalline while the thin films are amorphous. To understand the effect of Al doping on ionic conductivity, electrical measurements were done at room temperature by AC impedance spectroscopy forming ITO/LLTAlO/Al structure like capacitor. Highest ionic conductivity result, 0.96 × 10 −6 S•cm −1 , is obtained from the nominal thin film composition of Li 0.5 La 0.5 Ti 1−x Al x O 3 (x = 0.05) at room temperature measurements. Heat treatment is also conducted to investigate to understand its effect on ionic conductivity and the structure of the thin films. It is found that ionic conductivity enhances with annealing. Also, temperature dependent ionic conductivity measurements from 298 K to 385 K are taken in order to evaluate activation energy for Li-ion conduction.3 Li x Ti 1−x Al x O 3 was examined as bulk structure with compositions of x
<div>Accurate characterization of the nanocrystal shape with high statistical relevance is essential for exploiting the strongly shape-dependent properties of cuboidal nanoparticles towards applications. <br></div><div>This work presents the development of a new small-angle scattering form factor based on the superball geometry. The superball quantifies the characteristic rounding of corners and edges of cuboidalnanoparticles with a single parameter. Applied to small-angle scattering data of sufficiently monodisperse nanoparticles, the superball form factor enables differentiation between the effects of extended<br></div>particle size distribution and irregular particle shape. The quantitative application of the superball form factor is validated against microscopy data for a series of monodisperse nanoparticles and implemented into the user-friendly, open source software Sasview.
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