Untitled

doi:10.1002/adma.v21:17

Cited by 18 publications

(9 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The concept of the minimisation of the free volume can be applied in more complex systems such as those based on coatings of 3D nanoparticles [68][69][70][71][72][73] and 2D surfaces as in self-assembled monolayers. [74,75] Typically the surfaces of such systems are coated with surfactant materials that are not necessarily covalently bonded to the surface, and so the surfactant molecules can move on the surface depending on the coating density.…”

Section: Coated Nanoparticles With Hierarchical Structuresmentioning

confidence: 99%

What makes a liquid crystal? The effect of free volume on soft matter

et al. 2015

View full text Add to dashboard Cite

In this article, we probe the formation of liquid crystal and soft crystal phases as a consequence of minimising the free volume of the system either through design engineering of molecular shape or through deformation of molecular architecture. Following this concept, a number of realisations were made, for example, smectic A phases with variable layer spacing, smectic C phases without layer shrinkage, lattices of free space and fibres in N TB phases.Prologue: At the start of my thesis research in 1974, the knowledge of the structures of smectic liquid crystals was somewhat limited. Even though his thought predated the discovery of ferreoelectric behaviour in liquid crystals, George Gray had the idea that smectic C (SmC) liquid crystals might underpin potential new display applications. As I launched into synthesising new SmC variants, I started to think about why molecules should tilt over in their layers, and then onwards to question why do certain materials exhibit different forms of smectic B (SmB) phases, which was before their classification as hexatic and crystal B phases, etc. In those days I became very much interested in how the molecules pack together in condensed phases. With protractors, compasses and graph paper, the Cartesian coordinates of the atoms of a variety of molecular structures in their all trans forms were located, and their mass axes were determined for their structures by computer methods using ticker-tape which used to shoot out of the machine in volumes to yield just one result -the minimum moment of inertia. Flipping the structures about their inertia axes by 180°yielded the surface contours and the rotational volumes of the molecules. Packing them together in ways to minimise the free volume gave snapshot pictures of the local structures of various mesophases.[1] Over the passing years, I discarded this methodology for the following reasons: (1) the molecules in liquid crystal phases are rotationally disordered and are in dynamic fluctuation as demonstrated by neutron scattering studies [2,3]; (2) X-ray data showed that the molecules pack close enough together that they interpenetrate each other's independent rotational volumes, meaning they share each other's space [4,5]; (3) there were no ways to simulate the interpenetration of space, and what was free space and what was not; (4) there were only a few families of materials that could provide full data sets on structure versus phase formation; to this day there are still relatively few full homologous series of materials being reported; and lastly (5) there was no discussion of how to determine the energy cost of not fully packing space with molecules in order to minimise the remaining free volume. However, with the advent of research exploring liquid crystal materials of unconventional structure and new modelling methods such as density functional theory (DFT) simulations becoming available, our work again began to explore the steric packing arrangements of the molecules in condensed phases. [6][7][8][9][10] Then recently, one o...

show abstract

Section: Coated Nanoparticles With Hierarchical Structuresmentioning

confidence: 99%

What makes a liquid crystal? The effect of free volume on soft matter

et al. 2015

View full text Add to dashboard Cite

show abstract

“…An essential step towards the understanding of modern materials and their implementation in novel nano-electronic devices is the control and manipulation of their microscopic behavior [1][2][3]. Recently, the interrelationship between spin, charge, and lattice orders in high temperature superconductors (HTSs) has been at the center of a very animated discussion [4][5][6][7][8][9][10][11][12][13][14][15].…”

Section: Introductionmentioning

confidence: 99%

Networks of superconducting nano-puddles in 1/8 doped YBa₂Cu₃O_{6.5 +y}controlled by thermal manipulation

et al. 2014

View full text Add to dashboard Cite

While it is known that the nature and the arrangement of defects in complex oxides have an impact on the material functionalities, little is known about control of superconductivity by oxygen interstitial organization in cuprates. Here we report direct compelling evidence for the control of T c by manipulation of the superconducting granular networks of nanoscale puddles, made of ordered oxygen stripes, in a single crystal of YBa 2 Cu 3 O 6.5 + y with average formal hole doping p close to 1/8. Upon thermal treatments we were able to switch from a first network of oxygen defect striped puddles with OVIII modulation (q OVIII (a*) = (h + 3/8, k, 0) and q OVIII (a*) = (h + 5/8, k, 0)) to a second network characterized by OXVI modulation (q OXVI (a*) = (h + 7/16, k, 0) and qox-VI Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.(a*) = (h + 9/16, k, 0)) and finally to a third network with puddles of OV periodicity (q OV (a*) = (4/10, 1, 0) and q OV (a*) = (6/10, 1, 0)). We map the microscopic spatial evolution of the out of plane OVIII, OXVI and OV puddle nanosize distribution via scanning micro-diffraction measurements. In particular, we calculated the number of oxygen chains (n) and the charge density (hole concentration p) inside each puddle, analyzing areas of 160 × 80 μm 2 , and recording 12 800 diffraction patterns to reconstruct each spatial map. The high spatial inhomogeneity shown by all the reconstructed spatial maps reflects the intrinsic granular structure that characterizes cuprates and iron chalcogenides, disclosing the presence of several complex networks of coexisting superconducting domains with different lattice modulations, charge densities and gaps as in the proposed multi-gap scenario called superstripes.

show abstract

“…GO was synthesized from natural graphite powder by a modified Hummers method. [24,25] Exfoliation was carried out by ultrasonicating the GO dispersion under ambient condition. The as-prepared GO was dispersed in DMF solution.…”

Section: Methodsmentioning

confidence: 99%

“…The diffraction peak around 26.48 for graphite disappears in the pattern of GO and a broad peak is present at 2θ = 10.98, indicating the successful oxidation of raw graphite into graphite oxide. [25,27,28] After annealing, the diffraction peaks at 2θ = 10.98 disappears and a broad peak forms and moves closer to 2θ = 26.48 after 500 • C annealing than after 300 • C annealing. This indicates that the GO nanosheets can be reduced to rGO only by the simple high-temperature annealing.…”

Section: Characterizationmentioning

confidence: 96%

Flexible rGO/Fe₃O₄ NPs/polyurethane film with excellent electromagnetic properties*

Qiu

Hong-Jun

et al. 2019

Chinese Phys. B

View full text Add to dashboard Cite

Large-area and flexible reduced graphene oxide (rGO)/Fe3O4 NPs/polyurethane (PU) composite films are fabricated by a facile solution-processable method. The monolayer assembly of Fe3O4 nanoparticles with a high particle-stacking density on the graphene oxide (GO) sheets is achieved by mixing two immiscible solutions of Fe3O4 nanoparticles in hexane and GO in dimethylformide (DMF) by a mild sonication. The x-ray diffraction and Raman spectrum confirm the reduced process of rGO by a simple thermal treatment. The permittivity value of the composite in a frequency range of 0.1 GHz–18 GHz increases with annealing temperature of GO increasing. For 5-wt% rGO/Fe3O4 NPs/PU, the maximum refection loss (RL) of over −35 dB appears at 4.5 GHz when the thickness of film increases to 5 mm. The rGO/Fe3O4 NPs/PU film, exhibiting good electromagnetic properties over GHz frequency range, could be a potential candidate as one of microwave absorption materials in flexible electronic devices.

show abstract

Untitled

Cited by 18 publications

References 0 publications

What makes a liquid crystal? The effect of free volume on soft matter

What makes a liquid crystal? The effect of free volume on soft matter

Networks of superconducting nano-puddles in 1/8 doped YBa₂Cu₃O_{6.5 +y}controlled by thermal manipulation

Flexible rGO/Fe₃O₄ NPs/polyurethane film with excellent electromagnetic properties*

Contact Info

Product

Resources

About

Untitled

Cited by 18 publications

References 0 publications

What makes a liquid crystal? The effect of free volume on soft matter

What makes a liquid crystal? The effect of free volume on soft matter

Networks of superconducting nano-puddles in 1/8 doped YBa2Cu3O6.5 +ycontrolled by thermal manipulation

Flexible rGO/Fe3O4 NPs/polyurethane film with excellent electromagnetic properties*

Contact Info

Product

Resources

About

Networks of superconducting nano-puddles in 1/8 doped YBa₂Cu₃O_{6.5 +y}controlled by thermal manipulation

Flexible rGO/Fe₃O₄ NPs/polyurethane film with excellent electromagnetic properties*