In situ probing of electromechanical properties of an individual ZnO nanobelt

We report here, an investigation on electrical and structural-microstructural properties of an individual ZnO nanobelt via in situ transmission electron microscopy using an atomic force microscopy (AFM) system. The I-V characteristics of the ZnO nanobelt, just in contact with the AFM tip indicates the insulating behavior, however, it behaves like a semiconductor under applied stress. Analysis of the high resolution lattice images and the corresponding electron diffraction patterns shows that each ZnO nanobelt is a single crystalline, having wurtzite hexagonal structure (a=0.324 nm, c=0.520 66 nm) with a general growth direction of (1010)

Real-time fracture detection of individual boron nitride nanotubes in severe cyclic deformation processes

Real-time deformation of individual multiwalled boron nitride nanotubes (BNNTs) was investigated using an atomic force microscopy (AFM) stage installed inside the chamber of a transmission electron microscopy (TEM) system. These in situ AFM-TEM experiments were conducted in following two deformation regimes: a small-angle (∼65°) and a large-angle (∼120°) cyclic bending process. BNNTs survived from the low-angle test and their modulus was determined as ∼0.5 TPa. Fracture failure of individual BNNTs was discovered in the large-angle cyclic bending. The brittle failure mechanism was initiated from the outermost walls and propagated toward the tubular axis with discrete drops of applied force

Tuning Silicon Nanorods for Anodes of Li-Ion Rechargeable Batteries

Silicon is a promising anode material for Li-ion batteries in regarding of high capacity, low cost and safety, but it suffers poor cycling stability due to the pulverization induced by severe volume expansion/shrinkage (297%) during lithium insertion/extraction. In our previous investigation on aluminum nanorods anodes, it is found the selection of substrates in which Al nanorods grown plays the role in prevention of pulverization resulting in the increase of cycling lif

Facile electrochemical synthesis of antimicrobial TiO2 nanotube arrays

Infection-related complications have been a critical issue for the application of titanium orthopedic implants. The use of Ag nanoparticles offers a potential approach to incorporate antimicrobial properties into the titanium implants. In this work, a novel and simple method was developed for synthesis of Ag (II) oxide deposited TiO2 nanotubes (TiNTs) using electrochemical anodization followed by Ag electroplating processes in the same electrolyte. The quantities of AgO nanoparticles deposited in TiNT were controlled by selecting different electroplating times and voltages. It was shown that AgO nanoparticles were crystalline and distributed throughout the length of the nanotubes. Inductively coupled plasma mass spectrometry tests showed that the quantities of released Ag were less than 7 mg/L after 30 days at 37°C. Antimicrobial assay results show that the AgO-deposited TiNTs can effectively kill the Escherichia coli bacteria. Although the AgO-deposited TiNTs showed some cytotoxicity, it should be controllable by optimization of the electroplating parameters and incorporation of cell growth factor. The results of this study indicated that antimicrobial properties could be added to nanotextured medical implants through a simple and cost effective method

Direct Growth of High Mobility and Lowâ Noise Lateral MoS2â Graphene Heterostructure Electronics

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/138199/1/smll201604301_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/138199/2/smll201604301.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/138199/3/smll201604301-sup-0001-S1.pd

High-throughput, combinatorial synthesis of multimetallic nanoclusters

Multimetallic nanoclusters (MMNCs) offer unique and tailorable surface chemistries that hold great potential for numerous catalytic applications. The efficient exploration of this vast chemical space necessitates an accelerated discovery pipeline that supersedes traditional “trial-and-error” experimentation while guaranteeing uniform microstructures despite compositional complexity. Herein, we report the high-throughput synthesis of an extensive series of ultrafine and homogeneous alloy MMNCs, achieved by 1) a flexible compositional design by formulation in the precursor solution phase and 2) the ultrafast synthesis of alloy MMNCs using thermal shock heating (i.e., ∼1,650 K, ∼500 ms). This approach is remarkably facile and easily accessible compared to conventional vapor-phase deposition, and the particle size and structural uniformity enable comparative studies across compositionally different MMNCs. Rapid electrochemical screening is demonstrated by using a scanning droplet cell, enabling us to discover two promising electrocatalysts, which we subsequently validated using a rotating disk setup. This demonstrated high-throughput material discovery pipeline presents a paradigm for facile and accelerated exploration of MMNCs for a broad range of applications

Characterization and modeling of dislocation-precipitation interactions in aluminum alloys

Thesis (Ph.D.), School of Mechanical and Materials Engineering, Washington State Universit

Mechanics of cellulose nanocrystals and their polymer composites

The fabrication of cellulose nanocomposites with ultimate mechanical properties has received tremendous attention during the past decade. However, the published data has not been reviewed and systematically compared from mechanical point of view. The current study aims to fill this gap by providing a critical review on the published data on the mechanics of cellulose nanocrystals and their composites. The studies on individual cellulose nanocrystals show that their strength depends on the number and type of inter and intra hydrogen bonds on the cellulose chains, which are affected by the cellulose type and origin. It has been shown that the tensile modulus, yield strength and creep resistance are higher in cellulose nanocomposites than in unfilled polymers. However, above optimum cellulose content, the agglomeration of nanocrystals degrades the mechanical properties. Furthermore, cellulose nanocrystals enhance the structural stiffness of polymer composites at elevated temperatures. Formation of rigid nanocrystal network causes increase in the storage modulus (E0) and glass transition temperature

In-situ nanomechanical-electrical testing of one-dimensional materials

One-dimensional nanomaterials including nanotubes are building blocks for constructing various complex nanodevices. Boron nitride (BN) nanotubes with structure similar to carbon nanotube are known to be among the strongest insulators in the world. In this work, deformation of an individual BN nanotube is performed inside a high-resolution transmission electron microscope (TEM) using a piezo-driven atomic force microscope (AFM) and scanning tunneling microscope (STM)–TEM holder. The electrical and mechanical properties of individual BN nanotubes are obtained from the experimentally recorded I-V and force-displacement curves