Single Crystal Micro Research Articles

Compressive Deformation Behavior of Single Crystal Micro Pillar Fabricated in a Grain for Polycrystalline Pure Cu

Compressive Deformation Behavior of Single Crystal Micro Pillar Fabricated in a Grain for Polycrystalline Pure Cu

Insights Into the Solution Crystallization of Oriented Alq3 and Znq2 Microprisms and Nanorods.

Optimized solution-based methods to grow high quality micro- and nanocrystals of organic semi-conductors with defined size, shape and orientation are important to a variety of optoelectronic applications. In this context, we report the growth of single crystal micro- and nanostructures of the organic semiconductors Tris(8-hydroxyquinoline)aluminum (Alq3) and bis(8-hydroxyquinoline)zinc (Znq2) terminating in flat crystal planes using a combination of evaporative and antisolvent crystallization. By controlling substrate-specific nucleation and optimizing the conditions of growth, we generate vertically-oriented hexagonal prism arrays of Alq3, and vertical half-disks and sharp-edged rectangular prisms of Znq2. The effect of process variables such as ambient vapour pressure, choice of anti-solvent and temperature on the morphology and crystal habit of the nanostructures were studied and the results of varying them catalogued to gain a better understanding of the mechanism of growth.

High pressure single-crystal micro X-ray diffraction analysis with GSE_ADA/RSV software

GSE_ADA/RSV is a free software package for custom analysis of single-crystal micro X-ray diffraction (SCμXRD) data, developed with particular emphasis on data from samples enclosed in diamond anvil cells and subject to high pressure conditions. The package has been in extensive use at the high pressure beamlines of Advanced Photon Source (APS), Argonne National Laboratory and Advanced Light Source (ALS), Lawrence Berkeley National Laboratory. The software is optimized for processing of wide-rotation images and includes a variety of peak intensity corrections and peak filtering features, which are custom-designed to make processing of high pressure SCμXRD easier and more reliable.

Extended Mapping and Exploration of the Vanadium Dioxide Stress-Temperature Phase Diagram

Single-crystal micro- and nanomaterials often exhibit higher yield strength than their bulk counterparts. This enhancement is widely recognized in structural materials but is rarely exploited to probe fundamental physics of electronic materials. Vanadium dioxide exhibits coupled electronic and structural phase transitions that involve different structures existing at different strain states. Full understanding of the driving mechanism of these coupled transitions necessitates concurrent structural and electrical measurements over a wide phase space. Taking advantages of the superior mechanical property of micro/nanocrystals of VO(2), we map and explore its stress-temperature phase diagram over a phase space that is more than an order of magnitude broader than previously attained. New structural and electronic aspects were observed crossing phase boundaries at high-strain states. Our work shows that the actively tuning strain in micro/nanoscale electronic materials provides an effective route to investigate their fundamental properties beyond what can be accessed in their bulk counterpart.

Single-crystal micro/nanostructures and thin films of lamellar molybdenum oxide by solid-state pyrolysis of organometallic derivatives of a cyclotriphosphazene

The solid-state pyrolysis of organometallic derivatives of a cyclotriphosphazene is demonstrated to be a new, simple and versatile solid-state templating method for obtaining single-crystal micro- and nanocrystals of transition and valve metal oxides. The technique, when applied to Mo-containing organometallics N 3P 3[OC 6H 4CH 2CN·Mo(CO) 5] 6 and N 3P 3[OC 6H 4CH 2CN·Mo(CO) 4 py] 6, results in stand-alone and surface-deposited lamellar MoO 3 single crystals, as determined by electron and atomic force microscopies and X-ray diffraction. The size and morphology of the resulting crystals can be tuned by the composition of the precursor. X-ray photoelectron and infrared spectroscopies indicate that the deposition of highly lamellar MoO 3 directly on an oxidized (400 nm SiO 2) surface or (100) single-crystal silicon surfaces yields a layered uniphasic single-crystal film formed by cluster diffusion on the surface during pyrolysis of the metal-carbonyl derivatives. For MoO 3 in its layered form, this provides a new route to an important intercalation material for high energy density battery materials.

Cruciforms: Assembling Single Crystal Micro- and Nanostructures from One to Three Dimensions and Their Applications in Organic Field-Effect Transistors

The self-assembly behaviors and charge transport properties of cruciforms with anthracene as one axis were studied. By changing one axis of these cruciforms, the assembly morphologies of single crystal micro/nanostructures transferred from one dimension to three dimensions. This morphology transformation was controlled by the intermolecular interactions of cruciforms, which was proved by single crystal X-ray diffraction results and presented a facile way to synthesize different dimensional micro/nanostructures through molecular design. Field-effect transistors based on individual single crystal micro/nanostructure exhibited high performance. These results suggested the potential applications of cruciform in organic electronics.

Heterogeneous Three-Dimensional Electronics by Use of Printed Semiconductor Nanomaterials

We developed a simple approach to combine broad classes of dissimilar materials into heterogeneously integrated electronic systems with two- or three-dimensional layouts. The process begins with the synthesis of different semiconductor nanomaterials, such as single-walled carbon nanotubes and single-crystal micro- and nanoscale wires and ribbons of gallium nitride, silicon, and gallium arsenide on separate substrates. Repeated application of an additive, transfer printing process that uses soft stamps with these substrates as donors, followed by device and interconnect formation, yields high-performance heterogeneously integrated electronics that incorporate any combination of semiconductor nanomaterials on rigid or flexible device substrates. This versatile methodology can produce a wide range of unusual electronic systems that would be impossible to achieve with other techniques.

An interpretation of size-scale plasticity in geometrically confined systems.

The mesoscopic constitutive behavior of face-centered cubic metals as a function of the system characteristic dimension recently has been investigated experimentally. Strong size effects have been identified in both polycrystalline submicron thin films and single crystal micro pillars. The size effect is manifested as an increase in strength and hardening rate as the system dimensions are decreased. In this article, we provide a mechanistic interpretation for the observed mesoscopic behavior. By performing 3D discrete dislocation dynamics simulations of grains representative of the system microstructure and associated characteristic dimensions, we show that the experimentally observed size effects can be qualitatively described. In these simulations, a constant density of dislocation sources per unit of grain boundary area is modeled by sources randomly distributed at grain boundaries. The source length (strength) is modeled by a Gaussian distribution, in which average and standard deviation is independent of the system characteristic dimension. The simulations reveal that two key concepts are at the root of the observed plasticity size effect. First, the onset of plasticity is governed by a dislocation nucleation-controlled process (sources of various length, i.e., strengths, in our model). Second, the hardening rate is controlled by source exhaustion, i.e., sources are active only once as a result of the limited dislocation mobility arising from size and boundary effects. The model postulated here improves our understanding of why "smaller is stronger" and provides predictive capabilities that should enhance the reliable design of devices in applications such as microelectronics and micro/nano-electro-mechanical systems.

Zone centre phonons in high TcBa2YCu3O7

Abstract The zone centre phonons have been investigated in Ba2YCu3O7 using an angular force model. The theoretical values are in reasonable agreement with the available single crystal micro Raman and far-infrared transmission spectra measurements. It indicates that the observed transmission minima are due to phonon absorption.