Improving the Electrochemical Properties of the Manganese-Based P3 Phase by Multiphasic Intergrowth.

Layered transition-metal oxides are one kind of the most promising cathode materials for sodium-ion batteries. In this study, we propose a strategy to enhance the electrochemical properties of P3-type manganese-based layered oxide cathode by introducing a small amount of layered P2 and Li-O'3 phases. Powder X-ray diffraction (PXRD) structural refinement and aberration-corrected scanning transmission electron microscopy (STEM) are performed to confirm the microstructures of different samples.

Size effect on order-disorder transition kinetics of FePt nanoparticles.

The kinetics of order-disorder transition of FePt nanoparticles during high temperature annealing is theoretically investigated. A model is developed to address the influence of large surface to volume ratio of nanoparticles on both the thermodynamic and kinetic aspect of the ordering process; specifically, the nucleation and growth of L10 ordered domain within disordered nanoparticles. The size- and shape-dependence of transition kinetics are quantitatively addressed by a revised Johnson-Mehl-Avrami equation that included corrections for deviations caused by the domination of surface nucleation in nanoscale systems and the non-negligible size of the ordered nuclei.

An improved loop test for experimentally approaching the intrinsic strength of alumina nanoscale whiskers.

An improved loop test, which consists of twisting a loop in a nanoscale whisker adhered to a transmission electron microscopy (TEM) grid or other flat substrate and pulling the ends until the loop breaks, was developed for experimentally approaching the intrinsic strength of the whisker material. Alumina whiskers with diameters in the 82-320 nm range, as test targets, exhibited an average fracture strength of 39.1 GPa with a maximum of 48.

Predicting the size- and shape-dependent cohesive energy and order-disorder transition temperature of Co-Pt nanoparticles by embedded-atom-method potential.

The cohesive energy (CE) of CoPt nanoparticles (NPs) with different sizes and shapes have been calculated by embedded-atom-method (EAM) potential. It is shown that CE of NPs with order or disorder structures decreases with the decrease of particle size, while the shape effects become obvious only at small size. The CE difference per atom between order and disorder structures decreases with the decrease of particle size, indicating that the possibility of order-disorder transition in small size becomes larger compared with these in large size.

Novel C/Cu sheath/core nanostructures synthesized via low-temperature MOCVD.

C/Cu sheath/core nanocable arrays were mass-produced on various substructures, such as Si, SiO(2), Cu or glass, by using a one-step low-temperature metal-organic chemical vapor deposition. The novel nanostructures consist of a faceted Cu nanowire core with six side surfaces and four top surfaces, and a sheath of carbon. The as-synthesized nanocables are demonstrated excellent oxidization resistance and field emission properties, and are expected to be excellent candidates as nano-interconnectors, or nanocables, in electronic devices and nano-emitters for field emissions.

Universal relation for size dependent thermodynamic properties of metallic nanoparticles.

The previous model on surface free energy has been extended to calculate size dependent thermodynamic properties (i.e., melting temperature, melting enthalpy, melting entropy, evaporation temperature, Curie temperature, Debye temperature and specific heat capacity) of nanoparticles.

Size-, shape- and composition-dependent alloying ability of bimetallic nanoparticles.

Based on the surface-area-difference model, the formation enthalpies and the formation Gibbs free energies of bimetallic nanoparticles are calculated by considering size and shape effects. Composition-critical size diagrams were graphed for bulk immiscible bimetallic nanoparticles with the developed model. The results reveal that both the formation enthalpy and formation Gibbs free energy decrease with the decrease of particle size.

Modeling size effects on the surface free energy of metallic nanoparticles and nanocavities.

Based on the rigorous consideration of the bond broken rule and surface relaxation, a model for the size-dependent surface free energy of face-centered-cubic nanoparticles and nanocavities is presented, where the surface relaxation is calculated by the BOLS relationship. It is found that the surface free energy of nanoparticles and nanocavities represents a reverse size effect-the surface free energy of nanoparticles decreases with the decrease of particle size while it rises with the shrinkage of cavities. The size effect on the surface free energy of nanoparticles and nanocavities is not evident in large size ranges, while it becomes more and more distinct with decreasing size, especially for sizes smaller than 10 nm.

[Preparation, characterization and property of bamboo-like alpha-Fe2 O3 nanobars].

Firstly, hydroxide iron precursor was prepared by the co-precipitation method through using nitric iron as the source of iron, ammonia as precipitants, and poly-glycol as dispersant. Secondly, the precursor was calcined at 450 degrees C for 2 h under the protection of nitrogen. Finally, the images and structures of resultant powders were investigated by transmission electron microscopes (TEM), X-ray diffraction (XRD), Raman spectrum and the near-edge X-ray absorption fine structure (NEXAFS), respectively, and the magnetic property of resultant powders was measured by a vibrating sample magnetometer (VSM HH-50).

Wear behavior of light-cured dental composites filled with porous glass-ceramic particles.

Wear resistance is still perceived to be one of the most important limiting factors in the long-term performance of dental restorations. Consequently, a range of different materials have been used as filler particles to reduce the rate of wear, particularly in posterior restorations. In this study, novel bioactive glass-ceramic powders exhibiting different nominal calcium-mica to fluorapatite ratios were used as fillers for light-cured dental composites.

Effect of porous glass-ceramic fillers on mechanical properties of light-cured dental resin composites.

Objectives: The aim of this work was to study the effect of porous particles on the mechanical properties of dental resin composites.

Methods: Two kinds of glass-ceramic powders with different calcium-mica to fluorapatite ratio were used as inorganic fillers for light-cured dental resin composites. The glass-ceramic particles were etched to introduce porous structures.

Structure of Unsupported Small Palladium Nanoparticles.

A tight binding molecular dynamics calculation has been conducted to study the size and coordination dependence of bond length and bond energy of Pd atomic clusters of 1.2-5.4 nm in diameter.

Preparation of an electrodeposited hydroxyapatite coating on titanium substrate suitable for in-vivo applications.

In this paper the porous hydroxyapatite coating on Ti implant materials was prepared by the process of electrodeposition, hydrothermal and sinter. The surface morphology, bond strength and thickness of HA coatings were investigated by SEM, AFM, and its biocompatibility was evaluated by cytotoxicity experiments and implant experiments, respectively. Results showed that (1) The HA coatings was 50 microm thickness and adhered on the Ti substrate strongly, which bond strength reached 38 MPa.