Japan: Goedkope verf op komst die zou beschermen tegen zeer hoog frequente straling

donderdag, 22 januari 2009 - Categorie: Berichten Internationaal

Bron: Journal of the American Chemical Society (DOI:10.1021/ja807943v), the New Scientist en ''EMFacts Consultancy''. 19 januari 2009

Cheap paint could protect against super-fast wireless''

From the Beaconsfield Action Group:

Auteur: Colin Barras

As wireless communications become faster, it's not just older, slower
devices that are left behind. The shielding that protects sensitive
electronic equipment like that used in hospitals is becoming
increasingly obsolete as new, higher frequencies are used to send
data.

Now Japanese researchers have come to the rescue with a new metal-rich
coating designed to protect newly vulnerable devices. The development
is timely: while the latest wireless communications use
electromagnetic waves with a frequency of over 100 gigahertz, the best
wave absorbers commercially available are effective only up to around
half that.

The 120 GHz band, for example, can send data at up to 10 gigabits per
second. That's fast enough for the real-time transmission of
uncompressed video in high-definition TV format, and rivals the speed
of the fastest wired local area networks.

Iron constitution
The ability to block electromagnetic (EM) waves comes about when a
material's magnetic field resonates at the same frequency as the wave.
Wave absorbers are usually made from iron-rich oxides, but
higher-frequency transmissions outstrip the power of iron to absorb
electromagnetic waves.

However, the standard oxide coating – which contains barium as well
as iron – has a maximum resonance frequency that is outstripped at
48 GHz.

Shin-ichi Ohkoshi's team at the University of Tokyo in Japan has just
identified a new aluminium-iron oxide able to block waves with a
frequency almost four times higher.

The team used a sensitive magnetometer to confirm that a powder of the
new oxide can absorb EM waves of up to 182 GHz at room temperature.

Protective paint The composition of the new material somehow distorts
the bonds between iron and oxygen from their usual shape, which the
team believes explains the material's magnetic properties. Learning
more about this effect may make it possible to identify new metal
oxides that can absorb EM waves at even higher frequencies.
Particles of the new material could be incorporated in a paint to
shield sensitive equipment in medical areas, labs, or aeroplanes from
the effects of high-speed wireless communications, says Ohkoshi, who
adds that the paint would be relatively cheap to make because
aluminium and iron are abundant materials.

''We collaborated with DOWA Electronics, a Japanese industrial company
to make a 100-kilogram sample order,'' says Ohkoshi. ''The
manufacturing cost is very cheap – around Ł10 ($14) per kg.''

Journal reference: Journal of the American Chemical Society (DOI:
10.1021/ja807943v)



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