JoVE Visualize What is visualize?
Stop Reading. Start Watching.
Advanced Search
Stop Reading. Start Watching.
Regular Search
Find video protocols related to scientific articles indexed in Pubmed.
Atomic-scale control of TiO6 octahedra through solution chemistry towards giant dielectric response.
Sci Rep
PUBLISHED: 06-11-2014
Show Abstract
Hide Abstract
The structures of many important functional oxides contain networks of metal-oxygen polyhedral units i.e. MOn. The correlation between the configurations and connectivities of these MOn to properties is essentially important to be well established to conduct the design, synthesis and application of new MOn-based functional materials. In this paper, we report on an atomic-scale solution-chemistry approach that for the first time enables TiO6 octahedral network control starting from metastable brookite TiO2 through simultaneously tuning pH values and interfering ions (Fe(3+), Sc(3+), and Sm(3+)). The relationship between solution chemistry and the resultant configuration/connectivity of TiO6 octahedra in TiO2 and lepidocrocite titanate is mapped out. Apart from differing crystalline phases and morphologies, atomic-scale TiO6 octahedral control also endows numerous defect dipoles for giant dielectric responses. The structural and property evolutions are well interpreted by the associated H(+)/OH(-) species in solution and/or defect states associated with Fe(3+) occupation within TiO6 octahedra. This work therefore provides fundamental new insights into controlling TiO6 octahedral arrangement essential for atomic-scale structure-property design.
Related JoVE Video
Electron-pinned defect-dipoles for high-performance colossal permittivity materials.
Nat Mater
PUBLISHED: 05-22-2013
Show Abstract
Hide Abstract
The immense potential of colossal permittivity (CP) materials for use in modern microelectronics as well as for high-energy-density storage applications has propelled much recent research and development. Despite the discovery of several new classes of CP materials, the development of such materials with the required high performance is still a highly challenging task. Here, we propose a new electron-pinned, defect-dipole route to ideal CP behaviour, where hopping electrons are localized by designated lattice defect states to generate giant defect-dipoles and result in high-performance CP materials. We present a concrete example, (Nb+In) co-doped TiO? rutile, that exhibits a largely temperature- and frequency-independent colossal permittivity (> 10(4)) as well as a low dielectric loss (mostly < 0.05) over a very broad temperature range from 80 to 450 K. A systematic defect analysis coupled with density functional theory modelling suggests that triangular In?(3+)Vo(••)Ti(3+) and diamond shaped Nb?(5+)Ti(3+)A(Ti) (A = Ti(3+)/In(3+)/Ti(4+)) defect complexes are strongly correlated, giving rise to large defect-dipole clusters containing highly localized electrons that are together responsible for the excellent CP properties observed in co-doped TiO?. This combined experimental and theoretical work opens up a promising feasible route to the systematic development of new high-performance CP materials via defect engineering.
Related JoVE Video
A (3 + 3)-dimensional "hypercubic" oxide-ionic conductor: type II Bi2O3-Nb2O5.
J. Am. Chem. Soc.
PUBLISHED: 04-18-2013
Show Abstract
Hide Abstract
The high-temperature cubic form of bismuth oxide, ?-Bi2O3, is the best intermediate-temperature oxide-ionic conductor known. The most elegant way of stabilizing ?-Bi2O3 to room temperature, while preserving a large part of its conductivity, is by doping with higher valent transition metals to create wide solid-solutions fields with exceedingly rare and complex (3 + 3)-dimensional incommensurately modulated "hypercubic" structures. These materials remain poorly understood because no such structure has ever been quantitatively solved and refined, due to both the complexity of the problem and a lack of adequate experimental data. We have addressed this by growing a large (centimeter scale) crystal using a novel refluxing floating-zone method, collecting high-quality single-crystal neutron diffraction data, and treating its structure together with X-ray diffraction data within the superspace symmetry formalism. The structure can be understood as an "inflated" pyrochlore, in which corner-connected NbO6 octahedral chains move smoothly apart to accommodate the solid solution. While some oxide vacancies are ordered into these chains, the rest are distributed throughout a continuous three-dimensional network of wide ?-Bi2O3-like channels, explaining the high oxide-ionic conductivity compared to commensurately modulated phases in the same pseudobinary system.
Related JoVE Video
Superstructure of Mullite-type KAl9O14.
Chem Mater
PUBLISHED: 01-19-2013
Show Abstract
Hide Abstract
Large whiskers of a new KAl9O14 polymorph with mullite-type structure were synthesized. The chemical composition of the crystals was confirmed by energy-dispersive X-ray spectroscopy, and the structure was determined using single-crystal X-ray diffraction. Nanosized twin domains and one-dimensional diffuse scattering were observed utilizing transmission electron microscopy. The compound crystallizes in space group P21/n (a = 8.1880(8), b = 7.6760(7), c = 8.7944(9) Å, ? = 110.570(8)°, V = 517.50(9) Å(3), Z = 2). Crystals of KAl9O14 exhibit a mullite-type structure with linear edge-sharing AlO6 octahedral chains connected with groups of two AlO4 tetrahedra and one AlO5 trigonal bipyramid. Additionally, disproportionation of KAl9O14 into K ?-alumina and corundum was observed using in situ high-temperature optical microscopy and Raman spectroscopy.
Related JoVE Video
K(0.46)Na(0.54)NbO3 ferroelectric ceramics: chemical synthesis, electro-mechanical characteristics, local crystal chemistry and elastic anomalies.
Dalton Trans
PUBLISHED: 03-31-2011
Show Abstract
Hide Abstract
K(0.46)Na(0.54)NbO(3) ceramics have been fabricated via a chemical synthesis route. It was found that 500 °C heat treatment is sufficient to crystallize the niobate powder and the ceramic sintered at 1080 °C in air shows good ferroelectric and piezoelectric properties (P(r) ~ 15 ?C cm(-2), d(33) ~ 120 pC N(-1)). Electron diffraction patterns not only determine the space group symmetry of Pcm2(1) for the first time, but also reveal structural disorder in K(0.46)Na(0.54)NbO(3), and 1-D correlated strings of Nb-O atomic displacements are suggested to account for the polar behaviour. Elastic constants such as the bulk and shear moduli as well as their evolution with temperature were also measured using the resonant ultrasound spectroscopy method.
Related JoVE Video
An orthophosphate semiconductor with photooxidation properties under visible-light irradiation.
Nat Mater
PUBLISHED: 04-30-2010
Show Abstract
Hide Abstract
The search for active semiconductor photocatalysts that directly split water under visible-light irradiation remains one of the most challenging tasks for solar-energy utilization. Over the past 30 years, the search for such materials has focused mainly on metal-ion substitution as in In(1-x)Ni(x)TaO(4) and (V-,Fe- or Mn-)TiO(2) (refs 7,8), non-metal-ion substitution as in TiO(2-x)N(x) and Sm(2)Ti(2)O(5)S(2) (refs 9,10) or solid-solution fabrication as in (Ga(1-x)Zn(x))(N(1-x)O(x)) and ZnS-CuInS(2)-AgInS(2) (refs 11,12). Here we report a new use of Ag(3)PO(4) semiconductor, which can harness visible light to oxidize water as well as decompose organic contaminants in aqueous solution. This suggests its potential as a photofunctional material for both water splitting and waste-water cleaning. More generally, it suggests the incorporation of p block elements and alkali or alkaline earth ions into a simple oxide of narrow bandgap as a strategy to design new photoelectrodes or photocatalysts.
Related JoVE Video
Structures and phase transitions in (MoO2)2P2O7.
Inorg Chem
PUBLISHED: 02-06-2010
Show Abstract
Hide Abstract
We report structural investigations into (MoO(2))(2)P(2)O(7) using a combination of X-ray, neutron and electron diffraction, and solid-state NMR supported by first principles quantum chemical calculations. These reveal a series of phase transitions on cooling at temperatures of 377 and 325 K. The high temperature gamma-phase has connectivity consistent with that proposed by Kierkegaard at room temperature (but with improved bond length distribution), and contains 13 unique atoms in space group Pnma with lattice parameters a = 12.6577(1) A, b = 6.3095(1) A, c = 10.4161(1) A, and volume 831.87(1) A(3) from synchrotron data at 423 K. The low temperature alpha-structure was indexed from electron diffraction data and contains 60 unique atoms in space group P2(1)/c with cell parameters a = 17.8161(3) A, b = 10.3672(1) A, c = 17.8089(3) A, beta = 90.2009(2) degrees, and volume 3289.34(7) A(3) at 250 K. First principles calculations of (31)P chemical shift and J couplings were used to establish correlation between local structure and observed NMR parameters, and 1D and 2D (31)P solid-state NMR used to validate the proposed crystal structures. The intermediate beta-phase is believed to adopt an incommensurately modulated structure; (31)P NMR suggests a smooth structural evolution in this region.
Related JoVE Video
Crystal growth of novel lanthanide-containing platinates K4[Ln6Pt2O15] (Ln = La, Pr, Nd, Sm) with a unique framework structure.
Inorg Chem
PUBLISHED: 02-28-2009
Show Abstract
Hide Abstract
Crystals of a new family of lanthanide-containing platinum oxides with a unique framework structure were grown out of molten hydroxide fluxes. The structure consists of a crystallographically well-behaved [Ln(6)Pt(2)O(15)](4-) framework permeated by channels filled with disordered atoms along the [100] and equivalent directions. Open-channel structures are rare in oxides and apparently unknown in platinate chemistry.
Related JoVE Video
Compositional uniformity, domain patterning and the mechanism underlying nano-chessboard arrays.
J Phys Condens Matter
Show Abstract
Hide Abstract
We propose that systems exhibiting compositional patterning at the nanoscale, so far assumed to be due to some kind of ordered phase segregation, can be understood instead in terms of coherent, single phase ordering of minority motifs, caused by some constrained drive for uniformity. The essential features of this type of arrangement can be reproduced using a superspace construction typical of uniformity-driven orderings, which only requires the knowledge of the modulation vectors observed in the diffraction patterns. The idea is discussed in terms of a simple two-dimensional lattice-gas model that simulates a binary system in which the dilution of the minority component is favoured. This simple model already exhibits a hierarchy of arrangements similar to the experimentally observed nano-chessboard and nano-diamond patterns, which are described as occupational modulated structures with two independent modulation wavevectors and simple step-like occupation modulation functions.
Related JoVE Video

What is Visualize?

JoVE Visualize is a tool created to match the last 5 years of PubMed publications to methods in JoVE's video library.

How does it work?

We use abstracts found on PubMed and match them to JoVE videos to create a list of 10 to 30 related methods videos.

Video X seems to be unrelated to Abstract Y...

In developing our video relationships, we compare around 5 million PubMed articles to our library of over 4,500 methods videos. In some cases the language used in the PubMed abstracts makes matching that content to a JoVE video difficult. In other cases, there happens not to be any content in our video library that is relevant to the topic of a given abstract. In these cases, our algorithms are trying their best to display videos with relevant content, which can sometimes result in matched videos with only a slight relation.