Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

New concept for structural colors

18.05.2018

Scientists of the University of Hamburg (TUHH), the ITMO-University in St. Petersburg and the Helmholtz-Center Geesthacht have developed a novel concept that enables colorants which are based on non-toxic materials, which further do not bleach in the sunlight and which do not lose their appearance under high processing temperatures (as needed for glazes of ceramics).

In contrast to conventional pigments, the color effect is not caused by the absorption of certain wavelengths, which are in turn missing from the reflection spectrum and thus cause the color impression. Structural colors generate color solely by a structure that lets certain wavelengths destructively interfere.


Abbildung: Vergleich der berechneten Reflexionsspektren zweier photonischer Gläser, einmal bestehend aus keramischen Vollkugeln (a) und einmal aus keramischen Hohlkugeln (b). Die Kugeldurchmesser betragen ca. 200 Nanometer und die Schalendicke der Hohlkugeln in (b) ca. 10 Nanometer.

Das rechte Bild zeigt ein wesentlich steileres Reflexionsspektrum, das eine bessere Farbsättigung der in diesem Fall blauen Farbe bedingt.

Die beiden Quader zeigen Ausschnitte der mit Kugeln befüllten Volumina, mittels derer die numerischen Simulationen durchgeführt wurden.

(b) Chromatizitätsdiagramm. Die Positionen der beiden Reflexionsspektren in (a) und (b) sind in Relation zum farblosen Weißpunkt eingetragen. Auf dem Umfang des Diagramms sind die reinen Farben gezeigt.

Das aus Hohlkugeln bestehende photonische Glas erzeugt eine Farbe, die im Vergleich zu dem aus Vollkugeln bestehenden photonischen Glas wesentlich näher am Umfang liegt – also viel reiner ist.

Often such pigments feature a color impression that is dependent on the direction of illumination as well as the angle under which the pigment is looked at. This one wants to prevent in many cases. To realize “non-iridescent” colors, a certain amount of disorder in the structural arrangement of the colorant is needed. However, this disorder has lead, so far, to only weakly saturated colors.

The group of Hamburg based scientist have managed now to resolve these conflicting requirements. For this purpose a new concept was developed, which is based on weakly ordered arrangements of spheres – a so called photonic glass – combined with a precise design of the spheres themselves.

The utilized hollow spheres have a diameter of around 200 nanometers with a ceramic shell of only around 10 nanometers thickness. Only the combination of the nearest neighbor ordering of these densely packed spheres and the hollow sphere character of the single particles allow a steep edge of the reflection spectrum (Figure 1b). The usefulness of this design approach is exemplified with a highly saturated blue color.

The photonic glass from hollow sphere particles produces a blue color much closer to the perimeter of the chromaticity diagram, thus a much purer color than that of the photonic glass from homogeneously filled spheres (Figure 1c). The team of researchers developed the theoretical framework for the description of this novel class of colorants and confirmed their predictions with extensive numerical simulations.

These principal findings which were produced under the lead of the scientists from Hamburg are further of importance for the development of non-toxic colorants, which also do not bleach under sun light and which are suited for high processing temperatures beyond 1000°C.

The manuscript was published in Scientific Reports, an Open Access-Journal of Nature.

Online: www.nature.com/articles/s41598-018-26119-8

Publication:
Guoliang Shang, Lukas Maiwald, Hagen Renner, Dirk Jalas, Maksym Dosta, Stefan Heinrich, Alexander Petrov, and Manfred Eich,
Photonic glass for high contrast structural color,
Scientific Reports, 8, 7804 (2018)

Further Information
Prof. Dr. Manfred Eich
Technische Universität Hamburg-Harburg (TUHH), Institut für Optische und Elektronische Materialien, Eißendorfer Straße 38, D-21073 Hamburg
und
Institut für Werkstoffforschung, Helmholtz-Zentrum Geesthacht, Max-Planck-Strasse 1, Geesthacht, D-21502, Germany,
Tel +49 40 42878 3147
E-Mail: m.eich@tuhh.de,
Website: www.tuhh.de/alt/oem/home.html

Jasmine Ait-Djoudi | idw - Informationsdienst Wissenschaft
Further information:
http://www.tuhh.de

More articles from Materials Sciences:

nachricht A new paradigm of material identification based on graph theory
17.06.2019 | Science China Press

nachricht Electron beam strengthens recyclable nanocomposite
17.06.2019 | Kanazawa University

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: The hidden structure of the periodic system

The well-known representation of chemical elements is just one example of how objects can be arranged and classified

The periodic table of elements that most chemistry books depict is only one special case. This tabular overview of the chemical elements, which goes back to...

Im Focus: MPSD team discovers light-induced ferroelectricity in strontium titanate

Light can be used not only to measure materials’ properties, but also to change them. Especially interesting are those cases in which the function of a material can be modified, such as its ability to conduct electricity or to store information in its magnetic state. A team led by Andrea Cavalleri from the Max Planck Institute for the Structure and Dynamics of Matter in Hamburg used terahertz frequency light pulses to transform a non-ferroelectric material into a ferroelectric one.

Ferroelectricity is a state in which the constituent lattice “looks” in one specific direction, forming a macroscopic electrical polarisation. The ability to...

Im Focus: Determining the Earth’s gravity field more accurately than ever before

Researchers at TU Graz calculate the most accurate gravity field determination of the Earth using 1.16 billion satellite measurements. This yields valuable knowledge for climate research.

The Earth’s gravity fluctuates from place to place. Geodesists use this phenomenon to observe geodynamic and climatological processes. Using...

Im Focus: Tube anemone has the largest animal mitochondrial genome ever sequenced

Discovery by Brazilian and US researchers could change the classification of two species, which appear more akin to jellyfish than was thought.

The tube anemone Isarachnanthus nocturnus is only 15 cm long but has the largest mitochondrial genome of any animal sequenced to date, with 80,923 base pairs....

Im Focus: Tiny light box opens new doors into the nanoworld

Researchers at Chalmers University of Technology, Sweden, have discovered a completely new way of capturing, amplifying and linking light to matter at the nanolevel. Using a tiny box, built from stacked atomically thin material, they have succeeded in creating a type of feedback loop in which light and matter become one. The discovery, which was recently published in Nature Nanotechnology, opens up new possibilities in the world of nanophotonics.

Photonics is concerned with various means of using light. Fibre-optic communication is an example of photonics, as is the technology behind photodetectors and...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

SEMANTiCS 2019 brings together industry leaders and data scientists in Karlsruhe

29.04.2019 | Event News

Revered mathematicians and computer scientists converge with 200 young researchers in Heidelberg!

17.04.2019 | Event News

First dust conference in the Central Asian part of the earth’s dust belt

15.04.2019 | Event News

 
Latest News

Uncovering hidden protein structures

18.06.2019 | Life Sciences

Monitoring biodiversity with sound: how machines can enrich our knowledge

18.06.2019 | Life Sciences

Schizophrenia: Adolescence is the game-changer

18.06.2019 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>